Standard Specifications for Highway Bridges AASHO 1949 - Fifth Edition

Standard specifications for highway bridges adopted by the AmericanAssociation of State Highway Officials.American Association of State Highway Officials.Washington, D.C., The Association, 1941.

http://hdl.handle.net/2027/mdp.49015001295238

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The American Assft■■on of Slate Hishway Officia■■

STANDARD SPECIFICATIONS

for

HIGHWAY BRIDGES

University of Michigan-Flint Library

4 9015 OOI2JI2SF

FLINT COLtEGE

STANDARD SPECIFICATIONS

for

HIGHWAY BRIDGES

Adopted by

The American Association of State Highway Officials

FIFTH EDITION

Second PrintingJune, 1950

Published by the Association

General Offices917 National Press Building

Washington, D. C.

19 4 9

Copyright, 1949, by

THE AMERICAN ASSOCIATION OF STATE HIGHWAY -OFFICIALS

J-4909

'i ' * 42287. ft (, CONTENTS

PageDivision I General Provisions 6Division II Construction 25Division III Design 1-1Division IV Materials -11Appendix A Tables of Moments and Shears, Standard Loadings 1138Appendix 15 Steel Column Formulas (special) 242Appendix C Truck Train and Equivalent Loadings 248

(1935 Specifications— for reference use.)Appendix D Permissible Unit Concrete Stresses for Rectangular Concrete

Columns 249Index 250

DIVISION I

General Provisions

Article PaceSECTION 1—Definition of Terms

1.1.1 Definition of Terms 6

SECTION 2— Proposal Requirements and Conditions

1.2.1 Contents of Proposal Form 81.2.2 Interpretation of Estimates 81.2.3 Examination of Plans. Specification and Site of the Work 81.2.4 Preparation of Proposal 91.2.5 Rejection of Proposals 91.2.0 Proposal Guaranty 91.2.7 Delivery of Proposal 9

1.2.8 Withdrawal of Proposal 91.2.9 Public Opening of Proposals 91.2.10 Disqualification of Bidders 91.2.11 Competency of Bidders 9

SECTION 3—Award and Execution of Contract

1.3.1 Consideration of Bids 101.3.2 Award of Contracts 101.3.3 Return of Proposal Guaranty 101.3.4 Requirements of Contract Bond 101.3.5 Execution of the Contract 101.3.0 Approval of Contract 101.3.7 Failure to Execute Contract 10

SECTION 4— Scope of the Work1.4.1 Intent of the Plans and Specifications 101.4.2 Special Work 111.4.3 Increased or Decreased Quantities 111.4.4 Extra Work 111.4.5 Temporary Crossings and Detours 111.4.0 Removal and Disposal of Structures and Obstructions 111.4.7 Rights in and Use of Materials Found on the Site 111.4.8 Final Cleaning Up 12

SECTION 6— Control of the Work

1.5.1 Authority of Engineer 121.5.2 Plans and Working Drawings 121.5.3 Deviations from the Plans 121.5.4 Coordination of Specifications and Plans 181.5.5 Cooperation by Contractor 131.5.0 Construction Stakes 131.5.7 Authority and Duties of Inspectors 131 .5.8 Inspection 141.5.9 Removal of Unauthorized and Defective Work , 141.5.10 Final Inspection 141.5.11 Disputed Claims 141 .5.12 Arbitration 15

'ii

CONTENTS

SECTION «—Control of MaterialsArticle Page

1.6.1 Source of Supply and Quality 151.6.2 Tests of Materials 151.6.3 Storage of Materials 161.6.4 Defective Materials 161.6.5 Silence of Specifications 16

SECTION 7—Legal Relations and Responsibility to Public1.7.1 Laws to Be Observed 161.7.2 Permits and Licenses 171.7.3 Patented Processes and Materials 171.7.4 Federal Participation 171.7.5 Sanitary Provisions 171.7.6 Public Safety and Convenience 171.7.7 Barricades and Warning Signs 171.7.8 Protection and Restoration of Property 181.7.9 Responsibility for Damages 181.7.10 Contractor's Responsibility for Work 181.7.11 Personal Liability of Public Officials 181.7.12 No Waiver of Legal Rights 18

SECTION 8—Prosecution and Progressl.S.J Subletting or Assignment of Contract 191.8.2 Prosecution of the Work lit1.8.3 Limitations of Operations 191.8.4 Character of Workmen and Equipment 191.8.5 Temporary Suspension of the Work 201.8.6 Determination and Extension of Contract Time 201.8.7 Failure to Complete on Time 201.8.8 Annulment of Contract 211.8.9 Termination of Responsibility 211.8.10 Compensation for Unreasonable Delays 21

SECTION 9— Measurement and Payment1.9.1 Measurements of Quantities 211.9.2 Scope of Payment 211.9.3 Payments for Increased or Decreased Quantities 221.9.4 Payments for Extra and Force Account Work 221.9.5 Payment for Omitted Items 231.9.6 Partial Payments 231.9.7 Acceptance and Final Payment 24

DIVISION II

Construction

SECTION 1—Excavation and Fill2.1.1 General 252.1.2 Preservation of Channel 252.1.3 Depth of Footings 252.1.4 Preparation of Foundations for Footings . 252.1.5 Cofferdams and Cribs 26

General 26Protection 26Drawings Required 26

(d) Removal 262.1.6 Pumping 262.1.7 Inspection 272.1.8 Backfill 272.1.9 Filled Spandrel Arches 272.1.10 Approach Embankment *£2.1.11 Classification of Excavation 2i2.1.12 Measurement and Payment 28

SECTION 2— Sheet Piles2.2.1 General 28

CONTENTS V

Article Page2.2.2 Timber Sheet Piles 282.2.3 Concrete Sheet Piles 282.2.4 Steel Sheet Piles 292.2.5 Measurement and Payment 29

SECTION 8— Bearing Piles

2.3.1 Materials 292.3.2 Design and Conditions of Use 292.3.3 Preparation for Driving 29

(a) Excavation 29(b) Caps 29(c) Collars 29(d) Pointing 29(e) Splicing Piles 30(f) Painting Steel Piles 30

2.3.4 Methods of Driving 30(a) General 30fb) Hammers for Timber and Steel Piles 30(c) Hammers for Concrete Piles 30(d) Additional Equipment 30(e) Leads 30(f) Followers 30(g) Water Jets 31(h) Accuracy of Driving 31

2.3.5 Defective Piles 312.3.6 Determination of Bearing Values 31

ia)

Loading Tests 31

b) Timber Pile Formulas 31

c) Concrete and Steel Piles 322.3.7 Test Piles 322.3.8 Order Lists for Piling 322.3.9 Storage and Handling of Timber Piles 332.3.10 Cutting Off Timber Piles 332.3.11 Cutting Off Steel or Steel Shell Piles 332.3.12 Capping Timber Piles 332.3.13 Manufacture of Precast Concrete Piles 33

General 33Class of Concrete 33Form Work 33

(d) Reinforcement 33(e) Casting 33(f) Finish 34(g) Curing 34

2.3.14 Storage and Handling of Precast Concrete Piles 342.3.15 Manufacture of Cast-in-Place Concrete Piles 34

(a) General 34(b) Inspection of Metal Shells 34(c) Class of Concrete 34(d) Reinforcement 34(e) Placing Concrete 34

2.3.16 Extensions or "Build-ups" 352.3.17 Painting Steel Piles and Steel Pile Shells 352.3.18 Measurement and Payment 35

(a) General 35(b) Method A 35(c) Method B 36(d) Falsework and Defective Piles 36(e) Additional Requirements 36

2.3.19 Payment for Test Piles 372.3.20 Payment for Loading Tests 37

SECTION 4—Concrete Masonry2.4.1 General 372.4.2 Care and Storage of Concrete Aggregates 372.4.3 Storage of Cement 372.4.4 Classes of Concrete 382.4.5 Classification and Proportioning of Concrete Mixtures 38

(a) Method A. Proportions Based on Strength 39

VI CONTENTS

Article Pas*(b) Method B. Proportions Based ou a Constant Cement h actor 40

2.4.G Consistency 412.4.7 Measurement of Materials 422.4.8 Mixing Concrete 42

(a J General 42

(b) Mixing at Site 42(c) Truck Mixing 43

(d) Partial Mixing at the Central Plant 43

le) Plant Mix 44

(£) Time of Hauling and Placing Mixed Concrete 44Ik) Hand Mixing 44(h) Delivery 44

(i) Reteinpering 442.4.0 Handling and Placing Concrete 44

(a^ General 44ib) Culverts 40(c) Girders, Slabs and Columns 40(d) Arches 47

2.4.10 Pneumatic Placing 472.4.11 Pumping 482.4.12 Depositing Concrete Under Water 482.4.13 Construction Joints 49

(a) General 4'J(b) Bonding 49

2.4.14 Rubble or Cyclopean Concrete 492.4.15 Concrete Exposed to Sea Water 492.4.10 Concrete Exposed to Alkali Soils or Alknli Water 502.4.17 Falsework and Centering 502.4.18 Forms 502.4.19 Removal of Falsework, Forms, and Housing 512.4.20 Concreting in Cold Weather 522.4.21 Curing Concrete 522.4.22 Expansion and Fixed Joints and Bearings 52

(a) Open Joints 52

(h) Filled Joints 53

(c) Steel Joints 53(d) Water Stops .,

.}

(e) Bearing Devices w

Finishing Concrete Surfaces

2.4.23 General 532.4.24 Class 1

, Ordinary Surface Finish 542.4.25 Class 2

,

Rubbed Finish 542.4.20 Class 3

, Tooled Finish 542.4.27 Class 4

,

Sand Blasted Finish 552.4.28 Class 5

, Wire Brushed or Scrubbed Finish 552.4.29 Class 0

,

Floated Surface Finish 55(a) Striking Off 55(b) Floating 55(c) Longitudinal Floating 5o

id) Transverse Floating 5.)

(e) Straightedging 50(f) Final Finishing 50

2.4.30 Sidewalk Finish 502.4.31 Pneumatically Applied Mortar 50

(a) General 50(h) Proportions 50(c) Water Content 50(dl Mixing 57(e) Nozzle Velocity

j'<

ff) Nozzle Position 57(g) Rebound Sand 57(h) Forms 57

(i) Joints 57:i) Bond 57<<k) Curing 57

(1) Reinforcement 5<2.4.32 Measurement and Payment 58

CONTENTS VII

Article p"8eSECTION 5—Reinforcement

2.5.1 Material 582.5.2 Order Lists ^2.5.3 Protection of Material °82.5.4 Fabrication

^j*

2.5.5 Mesh Reinforcement2.5.6 Bar Mat Reinforcement 592.5.7 Placing and Fastening2.5.8 Splicing 592.5.9 happing *!«2.5.10 Substitutions

J™2.5.11 Measurement

2r»

2.5.12 Payment 60

SECTION 6—Ashlar Masonry

2.0.1 Description 612.0.2 Materials ;>

}

2.0.3 Size of Stone gj

2.6.4 Surface Finishes of Stone «l2.6.5 Dressing Stone g

j

2.0.0 Stretchers "f,2.0.7 Headers J»2.0.8 Cores and Backing 622.6.9 Mixing Mortar 622.6.10 Laying Stone "2

(a) General g2

(b) Face Stone(<•) Stone Backing and Cores 63(d) Concrete Cores and Backing M

2.6.11 Leveling Courses gjj

2.6.12 Resetting g»

2.0.13 Dowels and Cramps 642.0.14 Copings „•*;2.6.15 Arches g

*

2.0.10 Pointing M2.0.17 Measurement and Payment ».>

SECTION 7—Mortar Rubble Masonry

2.7.1 Description §52.7.2 Materials «>•>2.7.3 Size g

g2.7.4 Headers g

j>

2.7.5 Shaping Stone gjj

2.7.6 Laying Stone g*>

2.7.7 Copings, Bridge Seats and Backwalls HH2.7.8 Arches "»2.7.!) Pointing g

i

2.7.10 Measurement and Payment O<

SECTION 8—Dry Rubble Masonry

2.8.1 Description gl

2.8.2 Materials g<

2.8.3 Size of Stone g<

2.8.4 Headers 672.8.5 Shaping Stone g

j

2.8.6 Laying Stone 672.8.7 Coping, Bridge Seats and Backwalls *>82.8.8 Measurement and Payment OS

SECTION 9—Brick Masonry

2.9.1 Description ''82.9.2 Materials g

o

2.9.3 Construction gg

2 9.4 Copings. Bridge Seats and Backwalls 692.9.5 Measurement and Payment 69

VIII CONTENTS

SECTION 10—Steel StructuresArticle Fabrication Page2.10.1 Type Fabrication 092.10.2 Quality of Workmanship 692.10.3 Storage of Materials 092.10.4 Straightening Material 702.10.5 Finish <02.10.6 liivet Holes 702.10.7 Punched Holes JO2.10.8 Reamed or Drilled Holes 702.10.9 Subpunching, Keaming and Shop Assembly 702.10.10 Accuracy of Punched and Subdrilled Holes 712.10.11 Accuracy of Keamed and Drilled Holes 712.10.12 Shop Assembling 712.10.13 Camber Diagram 712.10.14 Drifting of Holes 712.10.15 Match-Marking 712.10.16 Rivets 722.10.17 Field Rivets £2.10.18 Bolts and Bolted Connections U

(a) General <2(b) Unfinished Bolts 72(c) Turned Bolts 73(d) Special Ribbed Bolts <3

2.10.19 Riveting 732.10.20 Edge Planing . .• 732.10.21 Welds 732.10.22 Flame Cutting 742.10.23 Facing of Bearing Surfaces t*2.10.24 Abutting Joints 742.10.25 End Connection Angles 742.30.26 Lacing Bars 742.10.27 Finished Members 742.10.28 Web Plates 742.10.29 Bent Plates 752.10.30 Fit of Stiffeners 752.10.31 Eyebars 752.10.32 Annealing 702.10.33 Pins and Rollers <"2.10.34 Boring Pin Holes 7«2.10.35 Pin Clearances 702.10.36 Screw Threads '«2.10.37 Pilot and Driving Nuts 7b2.10.38 Notice of Beginning of Work 7b2.10.39 Facilities for Inspection jio2.10.40 Inspector's Authority 772.10.41 Mill Orders 772.10.42 Weighing of Members 772.10.43 Marking and Shipping 77

Erection2.10.44 Erection of Structure 772.10.45 Plans 7<2.10.46 Plant 782.10.47 Delivery of Materials 782.10.48 Handling and Storing Materials 782.10.49 Falsework J82.10.50 Methods and Equipment 782.10.51 Bearings and Anchorage 782.10.52 Straightening Bent Material 792.10.53 Assembling Steel 792.10.54 Riveting 792.10.55 Pin Connections 802.10.56 Misfits , §02.10.57 Removal of Old Structure and Falsework 80

Payment2.10.58 Basis of Payment 802.10.59 Payment for Test Eyebars 812.10.60 Pay Weight °1

CONTENTS IX

Article Paf?2.10.61 Variance in Weight gj2.10.62 Computed Weight 81

SECTION 11 —Bronze or Copper-Alloy Bearing andExpansion Plates

2.11.1 General §22.11.2 Materials gj{

2.11.3 Bronze Plates 822.11.4 Copper-Alloy Plates £

2

2.11.5 Placing • 822.11.6 Measurement and Payment 82

SECTION 12—Steel Grid Flooring2.12.1 General §32.12.2 Materials °32.12.3 Arrangement of Sections 832.12.4 Provision for Camber 832.12.5 Field Assembly 832.12.6 Connection to Supports 832.12.7 Welding 842.12.8 Repairing Damaged Galvanived Coatings 842.12.9 Concrete Filler 842.12.10 Painting

§42.12.11 Method of Measurement and Basis of Payment So

SECTION 13—Railings2.13.1 General 852.13.2 Materials §5

2.13.3 Line and Grade 85

Metal Railing2.13.4 Construction 852.13.5 Painting 85

Concrete Railing2.13.6 General 852.13.7 Materials 862.13.8 Railings Cast in Place 862.13.9 Precast Rails 8b2.13.10 Surface Finish 862.13.11 Expansion Joints °°

Stone and Brick Railing2.13.12 General 86

Wood Railing2.13.13 General 872.13.14 Measurement and Payment 87

SECTION 14—Painting Metal Structures2.14.1 General 872.14.2 Paint 872.14.3 Number of Coats and Color 872.14.4 Mixing of Paint 872.14.5 Weather Conditions 872.14.6 Application 88

(a) General 88(b) Brushing 88(c) Spraying fg

(d) Inaccessible Surfaces gg2.14.7 Removal of Paint 882.14.8 Thinning Paint 882.14.9 Painting Galvanized Surfaces 882.14.10 Cleaning of Surfaces 89

(a) General 89(b) Method A.—Hand Cleaning 89(c) Method B.— Sandblasting 89

(d) Method C— Flame Cleaning 89(e) Surfaces Inaccessible After Assembly 90

X CONTENTS

Article Pa&e2.14.11 Shop Painting 902.14.12 Field Painting 90

SECTION 15—Riprap2.ir,.l Materials M2.15.2 Dry Riprap, Class 1 for Slopes »J2.15.3 Dry Riprap Class 2 for Slopes 912.15.4 Mortared Riprap for Slopes .)-2.15.5 Grouted Riprap for Slopes j»2.15.6 Stone Riprap for Foundation Protection 922.15.7 Concrete Riprap in Bags 93

Concrete Slab Riprap2.15.8 General 932.15.9 Concrete Jg2.15.10 Placing

;>.$

2.15.11 Measurement and Payment J<i

SECTION 16— Concrete Cribbing2.16.1 General 942.16.2 Construction

J™2.16.3 Measurement and Payment J*SECTION 17 —Waterproofing

2.17.1 General ?i

2.17.2 Materials ; ._'

2.17.3 Storage of Fabric 9;j2.17.4 Preparation of Surface j|

|,

2.17.5 Application —General 952.17.6 Application— Details 902.17.7 Damage Patching •*<'2.17.8 Protection Course »«2.17.9 Measurement and Payment J'

SECTION 18—Dampprooflng2.18.1 General

?72.18.2 Materials 972.18.3 Preparation of Surface 9*2.18.4 Application »i2.18.5 Measurement and Payment J'

SECTION 19 —Name Plates2.19.1 General Requirements 97

SECTION 20—Timber Structures2.20.1 Materials W

(a) Lumber and Timber 98(b) Structural Shapes «

J

(c) Castings 89(d) Hardware 99

2.20.2 Timber Connectors 992.20.3 Storage of Material . 992.20.4 Workmanship 1002.20.5 Treated Timber 100

(a) Handling 100(b) Framing and Boring 100(c) Cuts and Abrasions 100(d) Bolt Holes 100(e) Temporary Attachment 100

2.20.6 Untreated Timber 1002.20.7 Treatment of Pile Heads 100

(a) General 10°(b) Method A. —Zinc Covering 101

(c) Method B—Fabric Covering 1012.20.8 Holes for Bolts, Dowels, Rods and Lag Screws 1012.20.9 Bolts and Washers 1012.20.10 Countersinking 1012.20.11 Framing 1022.20.12 Pile Bents 102

CONTENTS XI

Article Page

2.20.13 Framed Bents 102

(a) Mud Sills 102

(b) Concrete pedestals 102

(c) Sills 102(dj Posts 102

2.20.14 Caps 1022.20.15 Bracing 1032.20.10 Stringers 303

2.20.17 Plank Floors 1032.20.18 Laminated or Strip Floors 1032.20.19 Wheel Guards and Railings 104

2.20.20 Trusses 1042.20.21 Truss Housings 1042.20.22 Erection of Housing and Bailings 1042.20.23 Painting 1042.20.24 Measurement and Payment 104

SECTION 21—Preservative Treatments for Timber2.21.1 General 1042.21.2 Materials 1002.21.3 Preparation for Treatment 105

(a) Sorting 105

(b) Framing '. 105

(c) Incising 1052.21.4 Amount of Preservative 100

(a) Creosote, Creosote Coal Tar Solution or Creosote PetroleumSolution Treatment 106

(b) Salts Treatments 1002.21.5 Pressure Treatment Processes 10(1

SECTION 22—Timber Cribbing2.22.1 Material > 101;

(a) Timber 100

(b) Logs 1072.22.2 Preparation 10*2.22.3 Dimensions 10 <

(a) Timber 107

(b) Logs 10 1

2.22 A 'Construction 107

(a) Foundation JPJ(b) Mud Sills 10,

(c) Face Logs or Timbers 10](d) Ties 108

(e) Fastening 108

2.22.5 Filling 10S

2.22.0 Measurement and Payment 108

SECTION 23—Sectional Plate Pipe and Arches

2.23.1 Description 108

2.23.2 Materials 109

2.23.3 Description of Plates 10.J2.23.4 Forming and Punching Plates 109

2.23.5 Field Erection —Pipe Structures 109

2.23.6 Field Erection —Arches 110

2.23.7 Strutting Ill2.23.8 Arch Substructures and Headwalls JIT2.23.9 Workmanship J"2.23.10 Method of Measurement 113

2.23.11 Basis of Payment 118

SECTION 24—Wearing SurfacesSeparate Concrete Wearing Surface

2.24.1 Description 113

2.24.2 Measurement and Payment 113

Brick Wearing Surface2.24.3 General Requirements JJg2.24.4 Materials 1"

XII CONTENTS

Article2.24.52.24.62.24.72.24.82.24.92.24.102.24.112.24.122.24.132.24.14

2.24.152.24.162.24.172.24.182.24.192.24.202.24.21

2.24.222.24.232.24.24

2.24.25

2.24.26

2.24.27

2.24.282.24.29

PagePreparation of Subfloor 113Sand-Cement Bed 114Placing Bedding Course 114Laying the Brick 114Rolling the Brick 115Testing the Surface 115Applying Asphalt Filler 115Surface Dressing 115Opening to Traffic 115Measurement and Payment 115

Asphalt Block Wearing SurfaceGeneral Requirement 116Materials 116Preparation of Subfloor 116Mortar Bed 116Laying the Blocks 116Opening to Traffic 117Measurement and Payment 117

Bituminous CarpetsGeneral 117Materials 117Preparation of Subfloor 117

(a) Wood Subfloor 117(b) Concrete Subfloor 118

Construction of Tar Mat Surface 118(a) Prime Coat 118

(b) Second Coat 118

(c) Seal Coat 118Construction of Asphalt Mat Surface (Mixed Method) 119

'Prime Coat 119Second Coat 119

, Seal Coat 119Construction of Asphalt Mat Surface (Penetration Method) 120

(a) Prime Coat 120

(b) Second Coat 120Opening to Traffic 120Measurement and Payment 120

3.1.13.1.23.1.33.1.43.1.53.1.63.1.73.1.83.1.93.1.103.1.113.1.123.1.133.1.143.1.153.1.16

3.1.17

DIVISION III

Design

SECTION 1—General Features of DesignDetermination of Waterway Area 121Restricted Waterways 121

Channel Openings 121Pier Spacing and Location 121Size of Culvert Openings 122Length of Culverts 122Width of Roadway and Sidewalk 122Clearances 122Curbs and Safety Curbs 122Railings 124Drainage 124Superelevation 124Floor Surfaces 124Blast Protection 124Utilities 125Roadway Width, Curbs and Clearances for Tunnels 125

(a) Roadway Width 125

(b) Clearance Between Walls 125

(c) Curbs 126

(d) Vertical Clearance 126Roadway Width. Curbs and Clearances for Depressed Roadways 126

(a) Roadway Width 126

CONTENTS XIII

Si

Article Page

(b) Clearance Between Walls"

126(c) Curbs 126

3.1.18 Roadway Width, Curbs and Clearances, Underpasses 126(Undivided Highways)

(a) Widths 127

(b) Vertical Clearance 127(c) Curbs 127

SECTION 2— Loads3.2.1 Loads 1273.2.2 Dead Load 127

Loads on Culverts 128Rigid Culverts 128

3.2.3 Live Load 1283.2.4 Overload Provision 1293.2.5 Highway Loadings 129

(a) General 129

(b) H Loadings 129(c) H-S Loadings 129(d) Classes of Loadings 129(e) Designation of Loadings 129(f) Minimum Loading 130

3.2.6 Traffic Lanes 1303.2.7 Standard Trucks and Lane Loads 1303.2.8 Application of Loadings 132

(a) Traffic Lane Units 132

(b) Number and Position, Traffic Lane Units 132(c) Lane Loadings—Continuous Spans 132

(d) Loading for Maximum Stress 1333.2.9 Reduction in Load Intensity 1343.2.10 Electric Railway Loading 1343.2.11 Sidewalk, Curb, Safety Curb, and Railing Loading 134

(a) Sidewalk Loading 134

(b) Curb Loading 134(c) Safety Curb Loading 134

(d) Railing Loading 1353.2.12 Impact 135

(a) Group A 135(!>) Group B 135(c) Impact formula 135

3.2.13 Longitudinal Forces 1363.2.14 Wind Loads 1863.2.15 Thermal Forces 1373.2.16 Force of the Stream Current, Floating Ice and Drift 1373.2.17 Buoyancy 1373.2.18 Earth Pressure 137

SECTION 3—Distribution of Loads3.3.1 Distribution of Wheel Loads to Stringers and Floorbeams 138

(a) Position of Loads for Shear 138

(b) Bending Moment in Stringers 138(c) Bending Moment in Floor Beams 139

3.3.2 Distribution of Loads and Design of Concrete Slabs 139(a) Bending Moment, Cases A. B and C 139

(b) Edge Beams (Longitudinal) 141(c) Distribution Reinforcement 141

(d) Shear and Bond Stress in Slabs 141(e) Unsupported Edges (Transverse) 141

(f) Cantilever Slabs 141(g) Slabs Supported on Four Sides 142(h) Edge Distance of Wheel Load 142

(i) Span Lengths 1423.3.3 Distribution of Wheel Loads Through Earth Fills 1433.3.4 Distribution of Wheel Loads on Timber Flooring 143

(a) Flooring Transverse 143(b) Flooring Longtiudinal 143(c) Continuous Flooring 143

3.3.5 Steel Grid Floors 143

XIV CONTENTS

Article Page

(a) General . . 143(b) Floors Filled With Concrete 144(c) Open Floors 144

SECTION 4—Unit Stresses, Pile Loads and BearingPower of Soils

3.4.1 General 144Grouping of Loads :

(a) Group A 144

(b) Group B 144

Steel Structures (Permissible Unit Stresses)3.4.2 Structural Carbon Steel 1433.4.3 High Strength Rivets 14(i3.4.4 Wrought Iron 14<i3.4.5 Cast Steel and Cast Iron 1463.4.6 Bronze or Copper Alloy 1463.4.7 Structural Low-Alloy Steel 1463.4.8 Structural Nickel and Structural Silicon Steels 1473.4.0 Unit Stresses for Welding 1483.4.10 Bearing on Masonry 148

Concrete Structures3.4.11 Concrete Stresses 148

(a) Standard Notations and Assumptions 148(b) General 140(c) Flexure 140(d) Shear 140<e> Bond on Piles 140(fl Bearing on Bridge Seats 150(g) Columns 150

3.4.12 Reinforcement 1-50

Structural Grade 130Intermediate Grade 130

Timber Structures3.4.13 Standard Stress Grades and Working Stresses 1513.4.14 Formulas for the Computation of Stresses in Timber 152

(a) Horizontal Shear in Rectangular Beams 152(b) Axial Compression in Rectangular Columns 152(c) Axial Compression on Connector Joined Spaced Columns 153(d) Safe -Load on Round Columns 153

(e) Notched Beams 154

(f) Bearing on Inclined Surfaces 154(g) Timber Connectors 154

Miscellaneous3.4.15 Bearing Power of Foundation Soils 1543.4.16 Angles of Repose 1553.4.17 Bearing Power of Piling 155

(a) General 155(b) Case A—Capacity of Pile as a Structural Member 155(c) Case B—Capacity of Pile to Transfer Load to the Ground 15(1

(d) Case C—Capacity of the Ground to Support the Load Delivered by the Pile 157

(e) Maximum Design Loads for Piles 157(f) Uplift 158(g) Group Pile Loading 158

3.4.18 Moments. Shears and Floor Beam Reactions 158

SECTION 5—Substructures and Retaining Walls3.5.1 Piles 158

(a) General 158(b) Limitation of Use 158(c) Design Loads 150(d) Spacing. Clearances and Embedment 150(e) Batter Piles 150

CONTENTS XV

Article Page

(f) Buoyancy 15D(g) Concrete Piles (Precast) 15!

(h) Concrete Piles (Cast.in.Place) 160(i) Steel Piles 100(j) Steel Pile and Steel Pile Shell Protection 161

3.5.2 Footings 101

(a J Depth 10'Sb)

Anchorage 101c) Distribution of Pressure 101

d) Spread Footings 10-(e) Internal Stresses in Spread Footings 102

(f) Reinforcement 10.3(g) Transfer of Stress from Vertical Reinforcement 103

3.5.3 Abutments 103(a) General 103(b) Reinforcement for Temperature 104

(c) Wing Walls 104

(d) Drainage 1043.5.4 Retaining Walls 104

(a) General 164(b) Base or Footing Slabs 104

(c) Vertical Walls 165

(d) Counterforts and Buttresses 16._(e) Reinforcement for Temperature 16._if) Expansion and Contraction Joints 10^(g) Drainage 10..

3.5.5 Piers }g._(a) General ]''._(b) Pier Nose 16.

3.5.6 Tubular Steel Piers J0;_(a) Use J6T(b) Depth 16 ,

(c) Piling

]'

(d) Dimensions of Shell J''"(e) Splices and Joints 16<,

(f) Bracing 160

SECTION 6—Structural Steel Design

8.0.1 Number of Trusses or Girders 1003.0.2 Spacing of Trusses and Girders 1003.0.3 Effective Span 1003.6.4 Effective Depth ' 0.3.6.5 Alternating Stresses 1°<

3.6.6 Combined Stresses 1»<

3.0.7 Secondary Stresses 1§73.0.8 Rolled Beams J»<3.0.9 Limiting Lengths of Members 10 1

3.0.10 Deflection Jgn3.0.11 Depth Ratios J««3.0.12 Symmetrical Sections 1003.0.13 Effective Area of Angles in Tension 1693.6.14 Thickness of Metal 16p3.6.15 Compression Members JWJ3.6.16 Web Plates of Solid Rib Arches 1<0

3.0.17 Outstanding Legs of Angles and Bearing Stiffeners 1(03.6.18 Size of Pins 1 '°

Details of Design

3.6.19 Size of Rivets 1J03.6.20 Pitch of Rivets

>')}3.6.21 Pitch in Ends of Compression Members Iifl3.6.22 Maximum Pitch 1"'3.6.23 Stitch Rivets 1'13.0.24 Edge Distance of Rivets I'13.6.25 Long Rivets 171

3.6.26 Rivets in Tension l'l3.6.27 Parts Accessible I"13.6.28 Closed Sections and Pockets 1723.6.29 Eccentric Connections 172

XVI CONTENTS

Article PaBe

3.6.30 Strength of Connections 1723.6.31 Splices 1723.6.32 Indirect Splices 1723.6.33 Fillers 172

(a) Welding 172(b) Riveting 172

3.6.34 Gusset Plates 1733.6.35 Stay Plates 1733.6.36 Perforated Cover Plates 1743.6.37 Net Section at Pin Holes 1753.6.38 Net Section of Riveted Tension Members 1753.6.39 Location of Pins 1753.6.40 Pin Plates 1763.6.41 Forked Ends 1763.6.42 Pins and Pin Nuts 1763.6.43 Bolts 1763.6.44 Upset Ends 1763.6.45 Sleeve Nuts J763.6.46 Expansion and Contraction 17°3.6.47 Expansion Bearings 1763.6.48 Bronze or Copper Alloy Sliding Expansion Bearings 1773.6.49 Fixed Bearings 1773.6.50 Pedestals and Shoes 1773.6.51 Rollers 1'Z3.6.52 Inclined Bearings 17<

3.6.53 Anchor Bolts 17<

3.6.54 Name Plates 17»

Welding3.6.55 Welding— General 178

Floor System

3.6.56 Stiffness of Floor Members 1783.6.57 Stringers 1783.6.58 Cross Frames 1783.6.59 Floor Beams 1783.6.60 End Floor Beams 1793.6.61 End Panels 1793.6.62 End Connection of Floor Beams and Stringers 1793.6.63 Sidewalk Brackets 1793.6.64 Expansion Joints 179

Bracing

3.6.65 General 1793.6.66 Minimum Size of Angles 1803.6.67 Lateral Bracing 1803.6.68 Portal and Sway Bracing 1803.6.69 Deck Plate Girder Spans 1803.6.70 Half -Through Truss Spans 1803.6.71 Through Plate Girder Spans 1813.6.72 Bracing of Long Columns 181

Plate Girders

3.6.73 General 1813.6.74 Flange Sections 1813.6.75 Thickness of Web Plates 1813.6.76 Flange Rivets 1823.6.77 Flange Splices 1823.6.78 Web Splices 1823.6.79 Transverse End Stiffeners 1823.6.80 Transverse Intermediate Stiffeners 1823.6.81 Longitudinal Stiffeners 1833.6.82 Ends of Through Girders 1833.6.83 Sole Plates 1833.6.84 Masonry Bearings 1833.6.85 Camber 183

CONTENTS XVII

TrussesArticle Pa8e3.6.86 General 1833.6.87 Top Chords and End Posts 1°43.6.88 Bottom Chords 1843.6.89 Working Lines and Gravity Axes 1843.6.90 Camber • • • 1843.6.91 Riveted Tension Member in Pin-Connected Trusses 1843.6.92 Counters 1843.6.93 Eyebars 1843.6.94 Packing of Eyebars 1843.6.95 Diaphragms3.6.96 Sole Plates 1853.6.97 Masonry Bearings 1°5

Viaducts3.6.98 Type

1§53.6.99 Bents and Towers 1853.6.100 Batter 1853.6.101 Single Bents 1853.6.102 Bracing 1853.6.103 Bottom Struts J§»3.6.104 Depth of Girders 1863.6.105 Girder Connections and Bracing 1803.6.106 Sole and Masonry Plates 181)

SECTION 7—Concrete Design3.7.1 General Assumptions 1863.7.2 Standard Notations 187

(a) Rectangular Beams 18 i

(b) T-Beams 187(c) Beams Reinforced for Compression 187(d) Shear, Bond and Web Reinforcement 188

3.7.3. Design Formulas 188(a) Beams and Slabs 188(b) T-Beams 189(c) Shear, Bond and Web Reinforcement 190(d) Columns with Lateral Ties 192(e) Spiral Columns 192

3.7.4 Span Lengths 1923.7.5 Expansion }«3.7.6 T-Beams 192

(a) Effective Flange Width 192b) Shear 192

(c) Isolated Beams i»g(d) Diaphragms JJJjj

3.7.7 Reinforcement 193(a) Spacing 1««(b) Covering '. f»g(c) Splicing 193(d) Allowable Capacity of End Anchorage—Hooks 193(e) Extension of Reinforcement 193(f) Maximum Sizes 194

3.7.8 Compression Reinforcement in Beams 1943.7.9 Web Reinforcement 194

(a) General 194(b) Bent-up Bars J9|(c) Vertical Stirrups 19o(d) Anchorage JfS

3.7.10 Columns 195(a) General 195(b) Columns with Lateral Ties 196(c) Spiral Columns 196(d) Flexure and Direct Stress 196

3.7.11 Concrete Arches 197(a) Shape of Arch Ring 197b) Spandrel Walls 198c) Expansion Joints 198d) Reinforcement 198e) Waterproofing 198

XVIII CONTENTS

Article Page

(f) Drainage of Spandrel Fill 1983.7.12 Viaduct Bents and Towers 198

SECTION 8—Design of Timber Structures3.8.1 Bolts 1083.8.2 Washers 1993.8.3 Hardware for Seacoast Structures IBS)3.8.4 Columns and Posts 1993.8.5 Pile and Framed Bents 199

(a) Pile Bents 199(b) Framed Bents 199

(c) Sills and Mud bills 199

(d) Caps 200(e) Bracing 200(f) Pile Bent Abutments 200

3.8.0 Trusses 200(a) Joints and Splices 200(b) Floor Beams 201

(c) Hangers 201

id) Kyebars and Counters 201

(e) Bracing 201

(f) Camber 2013.8.7 Floors and Bailings 201

(a) Stringers 201

(b) Bridging 201

(c) Nailing Strips 201

(d) Flooring 202(e) Retaining Pieces 202(f) Wheel Guards 202(g) Drainage 202(h) Bailings 202

3.8.8 Fire Stops 202

SECTION 9—Composite Beams

3.9.1 General Assumptions 2033.9.2 Effective Flange Width 2033.9.3 Stresses 2033.9.4 Shear 2033.9.5 Deflection 2043.9.0 Shear Devices 204

SECTION 10—Sectional Plate Pipe3.10.1 General 2013.10.2 Gage of Side and Top Plates 2043.10.3 Minimum Height of Cover 20; >3.10.4 Gage of Bottom Plates 2053.10.5 Bolts 2053.10.0 Cover Exceeding Heights Specified in Table 1 20;)

3.10.7 Sizes of Pipe Not in Table 2053.10.8 Multiple Pipes 2053.10.9 Strutting 20;>

SECTION II— Sectional Plate Arches3.11.1 General 2063.11.2 Gages for Sectional Plate Arches 200

Rise3.11.3 Ratio 20b

Span3.11.4 Minimum Height of Cover 2003.11.5 Adjustment of Table 2003.11.0 Bolts 20!!3.11.7 Skewed Spans and Multiple Arches 20 13.11.8 Substructure Design 207

SECTION 12—Rating of Existing Bridges3.12.1 General 2073.12.2 Inventory Ratings 207

CONTENTS XIX

Article P**,!3.12.3 Operating Ratings

§0J3.12.4 Dead LoadTJSi3.12.5 Live Load

3.12.15 Minimum Wind Load*}{°3.12.7 Unit Stresses .f"?3.12.8 Traffic Lanes

3.12.5) Allowable Stresses (Columns)3.12.10 Batten Iilate Columns -"J3.12.11 Compression on Flanges of Learns and Girders £Ri3.12.12 Details of Design

ta) Strength of Connections(b) Splices

r,,,;

(c) Pins 2103.12.13 Field Inspection

DIVISION IV

Materials

SECTION 1—Cement4.1.1 General 2114.1.2 Sampling and Testing 211

SECTION 2—Water for Use with Cement4.2.1 Quality 2114.2.2 Tests 211

SECTION 3— Fine Aggregate4.3.1 Fine Aggregate 2124.3.2 Sand for Mortar 212

SECTION 4—Coarse Aggregates4.4.1 Coarse Aggregates

2J24.4.2 Hubble or Cyclopean Aggregate 212

SECTION 5—Reinforcement4.5.1 Bar Reinforcement 2124.5.2 Wire and Wire Mesh 2134.5.3 Bar Mat Reinforcement 2134.5.4 Structural Shapes 213

SECTION 6—Structural, Eyebar and Rivet Steels4.0.1 General 2134.0.2 Structural Carbon Steel and Lye Bar Steel 2134.0.3 Structural Silicon Steel 2134.6.4 Structural Low.Alloy Steel 2134.0.5 Structural Nickel Steel 2144.0.0 Structural Rivet Steel 2144.0.7 High.Strength Structural Rivet Steel 21.14.6.8 Copper Bearing Steels 2144.0.J) Full Size Tests 2144.0.10 Number and Size of Test Bars 2144.0.11 Selection of Test Bars 2144.6.12 Failure to Meet Requirements 2144.6.13 Record of Annealing 2144.6.14 Payments for Full.Size Tests 215

SECTION 7— Wrought Iron4.7.1 Wrought Iron Plates ... 2154.7.2 Rolled Wrought-Iron Shapes and Bars 21o4.7.3 Welded Wrought-Iron Pipe 215

SECTION 8—Steel Forgings4.8.1 Carbon Steel Forgings 215

XX CONTENTS

Article Page

SECTION 9— Steel Castings4.9.1 Carbon Steel Castings 2154.9.2 Chromium Alloy-Steel Castings 21o

SECTION 10—Gray-Iron Castings4.10.1 Gray Iron Castings 2154.10.2 Workmanship and Finish 2164.10.3 Cleaning 216

SECTION 11—Malleable Castings4.11.1 Malleable Castings 2164.11.2 Workmanship and Finish 2164.11.3 Cleaning 216

SECTION 12—Bronze or Copper-Alloy Bearing andExpansion Plates

4.12.1 Bronze Bearing and Expansion Plates 2164.12.2 Rolled Copper- Alloy Bearing and Expansion Plates 216

SECTION 13— Steel Piles4.13.1 Steel Piles 216

SECTION 14—Steel Sheet Piling4.14.1 Process 2174.14.2 Chemical Composition 2174.14.3 Physical Properties 2174.14.4 Bend Tests 2174.14.5 Miscellaneous Requirements 217

SECTION 15—Steel Grid Floors4.15.1 Steel 2174.15.2 Protective Treatment (Shop Coat) 2174.15.3 Concrete 218

SECTION 16—PaintPaint for Timber Structures

4.16.1 Paint for Timber Structures 218Aluminum Paint 218Black Paint 218

Paint for Metal4.16.2 Shop Coat (Prime Coat) 2194.16.3 First Field Coat 2194.16.4 Second Field Coat (Finish Coat) 219

(a) General 219(b) Green Graphite Bridge Paint 220(c) Black Bridge Paint 221

SECTION 17—Welding4.17.1 Welding Materials 223

SECTION 18—Sheet Metal for Water Stops and General Use4.18.1 Sheet Copper 2244.18.2 Sheet Lead 2244.18.3 Sheet Zinc 224

SECTION IB—Sectional Plate Pipe and Arches4.19.1 General 2244.19.2 Spelter Coating 2244.19.3 Galvanizing 2254.19.4 Sampling 2254.19.5 Chemical Analysis and Tests for Spelter Coating 2254.19.6 Certified Analysis and Guarantee 2254.19.7 Identification 2254.19.8 Bolts (for Connecting Plates) 2264.19.9 Nuts and Bolt Heads 226

(a)(b)

CONTENTS XXI

Article Page

4.19.10 Corrugations 2264.19.11 Gage Determination and Tolerance 2264.19.12 Field Inspection and Acceptance of Plates 220

SECTION 20—Stone for Masonry

4.20.1 Ashlar Stone 2264.20.2 Rubble Stone 2274.20.3 Riprap 227

SECTION 21— Brick4.21.1 Paving Brick 2274.21.2 Brick for Masonry 227

SECTION 22—Bituminous Materials and Joint Fillers4.22.1 Oil Asphalt Fillers 2274.22.2 Premolded Expansion Joint Fillers 228

Bituminous Carpets4.22.3 Tar 2284.22.4 Asphalt 228

Waterproofing Materials4.22.5 Asphalt 2294.22.6 Pitch 2211

4.22.7 Fabric 22V)

4.22.8 Tar for Absorptive Treatment 22V)

4.22.9 Tar Seal Coat 2294.22.10 Joint Fillers 2304.22.11 Inspection and Delivery 230

SECTION 23—Asphalt Paving Blocks4.23.1 General 2304.23.2 Asphaltic Cement 2304.23.3 Mineral Aggregate 231

4.23.4 Inorganic Dust 23.1

4.23.5 Manufacture 231

4.23.6 Physical Characteristics 231

(a) Size and Shape 231

(b) Composition 232

(c) Absorption Test 232

SECTION 24—Premolded Asphalt Plank4.24.1 General 232

SECTION 25—Structural Timber, Lumber and Piling4.25.1 Species of Woods 2324.25.2 Limitation of Use 2334.25.3 Grading of Yard Lumber 2334.25.4 Hewn and Round Timbers 233

Grading of Structural Timber4.25.5 General 234

(a) Grade of Timber 234(b) Commercial Grading Rules 234

4.25.6 General Requirements 234

Timber Piles4.25.7 General 2344.25.8 Quality4.25.9 Dimensions 235

SECTION 26—Timber Preservatives4.26.1 Preservatives 235

SECTION 27—Timber Connectors4.27.1 General 2304.27.2 Split Ring Connectors 2364.27.3 Tooth-Ring Connectors 2364.27.4 Shear Plate Connectors 2364.27.5 Claw-Plate Connectors 2374.27.6 Spike-Grid Connectors 237

INTRODUCTION

The compilation of these specifications began with the organization,in 1921, of the Committee on Bridges and Structures of the AmericanAssociation of State Highway Officials. During the period from 1921, untilthe specifications were printed in 1931, the specifications were graduallydeveloped, and as the several divisions were approved, from time to time,they were made available in mimeographed form for use of the State Highway Departments and other organizations. A complete specification wasavailable in 1926 and it was revised in 1928. Though they were not inprinted form, the specifications were valuable to the bridge engineeringprofession during the period of development.

The first edition of the Standard Specifications for Highway Bridgeswas published in 1931, and it was followed by the 1935, 1941 and 1944

editions. The present edition constitutes a revision of the 1944 specifications and it contains all revisions adopted up to April 1, 1948. Insofar aspossible, the revisions have been made to conform to the latest developmentsin the profession of bridge engineering and to current practice in bridgedesign.

The more important changes have been made in the Division on Design.Those which warrant special mention are the revision of axle loads onfloors, clarification of the application of live loads, distribution of loads,and a much improved specification on the bearing value of piles. Longplate girder spans are being used more extensively and the use of longitudinal stiffeners involved in the long spans has been provided for in thisedition.

The Specifications for Highway Bridges are intended to serve as a

standard or guide for the preparation of State specifications and forreference by bridge engineers. In the case of a number of States, the specifications have been adopted as basic, subject to certain supplementalspecifications which embody provisions designed to meet the local needsof the State in question. Thus, the printing of a State specification isobviated. Primarily, the specifications set forth minimum requirementswhich are consistent with current practice, and it is expected that certainmodifications will be necessary to suit local conditions. They apply to

ordinary highway bridges, and supplemental specifications are requiredfor unusual types and for long span bridges. It is recognized that for longspan bridges the uniform live load should be materially reduced, dependentupon the length of the span, and that the line of demarcation betweenshort and long spans should be in the range of 300 to 400 feet.

Specifications of the American Society for Testing Materials, theAmerican Welding Society, and the American Wood Preservers' Association are referred to or are recognized, and in the formulation of the specifications certain portions of the American Railway Engineering Association Specifications and of the June, 1940, report of the Joint Committeeon Standard Specifications for Concrete and Reinforced Concrete have been

utilized. The Association of State Highway Officials wishes to express itssincere appreciation to these organizations. Extensive reference has alsobeen made to the Standard Specifications for Highway Materials andMethods of Sampling and Testing, published by the American Associationof State Highway Officials.

HIGHWAY BRIDGES

The Committee on Bridges and Structures has jurisdiction over thebridge activities of the Association. The present membership of the Committee includes representatives of 48 States, the District of Columbia,Hawaii and the Public Roads Administration. The following have servedas chairmen of the Committee since its inception in 1921 : Messrs. E. F.Kelley, who pioneered the work of the Committee, Albin L. Gemeny andR. B. McMinn. Mr. Raymond Archibald, the present chairman, has servedin that capacity since the 1941 edition was published.

Suggestions for the improvement of the specifications will be welcomed.They should be sent to the Chairman, Committee on Bridges and Structures,A.A.S.H.O., Public Roads Administration, Washington 25, D. C.

Committee on Bridges and Structures

1948

Raymond Archibald, ChairmanChief, Bridge Division

Public Roads Administration, Washington 25, D. C.

ALABAMA —J. W. Chambers, Bridge Engineer, State Highway Department, Montgomery.

ARIZONA —R. A. Hoffman, Bridge Engineer, State Highway Department,Phoenix.

ARKANSAS—N. B. Garver, Principal Highway Engineer, State HighwayCommission, Little Rock.

CALIFORNIA —F. W. Panhorst, Bridge Engineer, Division of Highways,Department of Public Works, Sacramento.

COLORADO—Paul S. Bailey, Bridge Engineer, State Highway Department, Denver.

CONNECTICUT— J. F. Willis, Bridge Engineer, State Highway Department, Hartford.

DELAWARE—J. M. Gordon, Bridge Engineer, State Highway Department, Dover.

FLORIDA—W. E. Dean, Bridge Engineer, State Road Department,Tallahassee.

GEORGIA —C. N. Crocker, Bridge Engineer, State Highway Department,Atlanta.

IDAHO —Walter Albrethsen, Bridge Engineer, Department of PublicWorks, P. 0. Box 1467, Boise.

ILLINOIS —G. F. Burch, Bridge Engineer, Division of Highways, Department of Public Works and Buildings, Springfield.

INDIANA —J. R. Cooper, Engineer of Bridges, State Highway Commission, Indianapolis.

IOWA —E. W. Blumenschein, Engineer of Bridge Design, State HighwayCommission, Ames.

KANSAS —E. S. Elcock, Bridge Engineer, State Highway Commission,Topeka.

KENTUCKY —E. D. Smith, Bridge Engineer, Department of Highways,Frankfort.

LOUISIANA —N. E. Lant, Chief Engineer, J. B. Carter, Bridge Engineer,Department of Highways, Baton Rouge.

MAINE—M. L. Wilder, Bridge Engineer, State Highway Commission,Augusta.

MARYLAND —Walter C. Hopkins, Bridge Engineer, State Roads Commission, Baltimore.

MASSACHUSETTS— R. O. Spofford, Bridge Engineer, Department ofPublic Works, 100 Nashua Street, Boston.

MICHIGAN—G. M. Foster, Bridge Engineer, State Highway Department,Lansing.

MINNESOTA—M. O. Giertsen, Bridge Engineer, Department of Highways, 1246 University Avenue, St. Paul 4.

MISSISSIPPI —Chas. S. Hill, Bridge Engineer, State Highway Department, Jackson.

MISSOURI —V. W. Enslow, Engineer of Bridges, State Highway Commission, Jefferson City.

MONTANA —H. W. Holmes, Bridge Design Engineer, State HighwayCommission, Helena.

NEBRASKA—H. G. Schlitt, Bridge Engineer, Department of Roads andIrrigation, Lincoln.

8

4 HIGHWAY BRIDGES

NEVADA—E. T. Boardman, Bridge Engineer, Department of Highways,Carson City.

NEW HAMPSHIRE—H. E. LANGLEY, Bridge Engineer, State HighwayDepartment, Concord.

NEW JERSEY—Morris Good-kind, Bridge Engineer, State Highway Department, Trenton.

NEW MEXICO —E. B. Van de Greyn, Bridge Engineer, State HighwayCommission, Santa Fe.

NEW YORK—E. W. Wendell, Assistant Chief Engineer, Department ofPublic Works, Albany 1.

NORTH CAROLINA—T. B. Gunter, Jr., Bridge Engineer, State Highwayand Public Works Commission, Raleigh.

NORTH DAKOTA —Frank E. Cave, Bridge Engineer, State HighwayDepartment, Bismarck.

OHIO—G. R. Logue, Chief Engineer, Bureau of Bridges, Department ofHighways, Columbus.

OKLAHOMA —Homer X. White, Bridge Engineer, State Highway Commission, Oklahoma City.

OREGON—G. S. Paxson, Bridge Engineer, State Highway Commission,Salem.

PENNSYLVANIA —Leo A. Porter, Acting Bridge Engineer, Departmentof Highways, Harrisburg.

RHODE ISLAND—D. O. Cargill, Bridge Engineer, Department of PublicWorks, Providence.

SOUTH CAROLINA—W. J. Gooding, Bridge Engineer, State HighwayDepartment, Columbia.

SOUTH DAKOTA— K. R. Scurr, Bridge Engineer, State Highway Commission, Pierre.

TENNESSEE —L. W. Erickson, Bridge Engineer, Department of Highways and Public Works, Nashville.

TEXAS—R. B. Alexander, Bridge Engineer, State Highway Department,Austin.

UTAH —Maurice Housecroft, Chief Bridge Engineer, State Road Commission, Salt Lake City.

VERMONT —A. D. Bishop, Bridge Engineer, Department of Highways,Montpelier.

VIRGINIA —Wm. R. Glidden, Engineer of Bridges, Department of Highways, Richmond.

WASHINGTON —George Stevens, Bridge Engineer, Department of Highways, Olympia.

WEST VIRGINIA —L. L. Jemison, Bridge Engineer, State Road Commission, Charleston.

WISCONSIN —C. H. Kirch, Bridge Engineer, State Highway Commission,Madison.

WYOMING —W. H. Fisher, Bridge Engineer, State Highway Department,Cheyenne.

PUBLIC ROADS ADMINISTRATION— H. R. Angwin, Highway BridgeEngineer, Phelan Building, San Francisco 2, Calif.

R. B. Wright, Highway Bridge Engineer, Box 3900, Portland 8, Oreg.C. T. Nitteberg, Bridge Engineer, 502 U. S. Courthouse, Ft. Worth, Tex.

DISTRICT OF COLUMBIA— Harry R. Howser, Engineer of Bridges,District Building, Washington, D. C.

HAWAII —Wm. R. Bartels, Bridge Engineer, Territorial Highway Department, Territorial Office Building, Honolulu 10, T. H.

PUERTO RICO—Cecilio Delgado, Chief Civil Engineer, Department ofSurvey and Design of Roads and Bridges, Department of Interior,San Juan.

OFFICERS AND MEMBERS OF EXECUTIVE COMMITTEE

OF THE ASSOCIATION

1949

PRESIDENTW. W. POLK

Illinois

FIRST VICE PRESIDENTC. W. BROWN

Missouri

REGIONAL VICE PRESIDENTSFirst Region Second Region

SPENCER MILLER, JR. W. V. BAISE

New Jersey N. Carolina

Fourth RegionA. P. WINKLER

Montana

Third RegionC. M. ZIEGLER

Michigan

M. J. HOFFMANNMinnesota

T. H. CUTLER

Kentucky

H. E. SARGENT

Vermont

EXECUTIVE COMMITTEER. H. BALDOCK

Oregon

B. D. TALL A MYNew York

T. H. MACDONALD

Washington, D. C.

F. R. WHITE

Iowa

J. A. ANDERSON

Virginia

D. C. GREER

Texas

C. H. PURCELL

California

EXECUTIVE SECRETARYH. H. HALE

Washington, D. C.

TREASURERG. H. HENDERSON

Rhode Island

5

DIVISION I

General Provisions

SECTION I— Definition of Terms

1. 1. 1.—Definition of Terms.

In these specifications the following definitions shall obtain:

"State oe Commonwealth" —The State or Commonwealth ofacting through its authorized representatives.

"Commission or Department" —The State highway commission, department or other organization as constituted under the laws of saidState or Commonwealth for the administration of highway work(hereinafter referred to as commission).

"County"—The County of in which the work herein specified isto be done.

"Township or Town"—Any subdivision of the county used to designateor identify the location of the proposed work.

"Board" —The governing board of the county or township in charge ofthe work.

"Engineer" —The chief engineer of the commission acting either directlyor through his authorized representatives.

"Resident Engineer"—The person acting as authorized representative ofthe engineer in the supervision and inspection of the work.

"Inspector"—The authorized representative of the engineer assigned tomake a detailed inspection of any or all portions of the work,or materials therefor.

"Bidder" —The individual, firm, or corporation formally submitting a proposal for the work contemplated, or any portion thereof, actingdirectly or through an authorized representative.

"Contractor" —The individual, firm, or corporation undertaking the execution of the work under the terms of the contract and actingdirectly or through his or its agents or employes.

"Sub-Contractor" —The individual, firm, or corporation acting for or inbehalf of the contractor in the execution of all or any part ofthe contract.

"Plans"—Approved drawings or reproduction of drawings, including allnotes thereon, pertaining to the construction or details of thework contemplated in the contract.

"Specifications" —All provisions and requirements contained herein, together with all written or printed agreements and instructions,except notes on plans, made or to be made pertaining to themethod and manner of performing the work, or to the quantitiesand qualities of the materials to be furnished under the contract.

"Supplemental Specifications"—Certain supplemental directions, provisions and requirements not on the plans and adopted as apart of the contract with the express purpose that they shall

8

GENERAL PROVISIONS 7

prevail over the specifications contained in this book but notover special provisions.

"Special Provisions"—Specific clauses which shall prevail over all otherspecifications and over all plans, setting forth conditions orrequirements peculiar to the project under consideration andcovering work or materials involved in the proposal and estimatebut not satisfactorily covered by the specification.

"Instructions to Bidders" —All instructions, issued for the informationof bidders, pertaining to the requirements governing the submission of proposals, the quantities and qualities of materials,the performance of the work and payment therefor.

"Proposal"—The written proposal of the bidder, on the form furnished,for the work contemplated.

"Contract and Included Documents" —The agreement covering the performance of the work as provided in the specifications. Thecontract includes the advertisement, instruction to bidders,proposal, contract and contract bond, these specifications, supplemental specifications, general and detailed plans, all supplemental agreements entered into, and all general or specialprovisions pertaining to the work or materials therefor.

"Proposal Guaranty" —The security designated in the instructions tobidders or proposal, to be furnished by the bidder as a guarantyof good faith to enter into a contract for the work contemplatedif it be awarded to him.

"Contract Bond" —The bond, executed by the contractor and his surety,guaranteeing complete execution of the contract.

"Surety" —The individuals or corporate body which is bound with andfor the contractor, for the acceptable performance of the contract, and for his payment of all debts pertaining to the work.Where applying to the "Proposal Guaranty" it refers to theindividuals or corporate body which engages to be responsiblefor the bidder's acts in the execution of a satisfactory contractin the event of it being awarded to him.

"Right of Way"—The area designated by the engineer for use in constructing the structures covered by the contract, including theappurtenances thereto. The right of way so designated maybe either temporary or permanent.

"Roadway" —The portion of the right of way reserved for traffic.

"Temporary Structure" —Any structure required to maintain traffic whileconstructing or reconstructing structures, or parts of structurescovered by the contract. The temporary structure shall includeearth approaches thereto.

"Substructure" —All of that part of the structure below the bearings ofsimple and continuous spans, skewbacks of arches and tops offootings of rigid frames, and also backwalls, wingwalls andwing protection railings shall be considered as part of thesubstructure.

8 HIGHWAY BRIDGES

"Superstructure" —All of that part of the structure above the bearingsof simple and continuous spans, skewbacks of arches and topsof footings of rigid frames, except as noted above, shall beconsidered as part of the superstructure.

"Laboratory"—The testing laboratory of the commission or any other testing laboratory which may be designated by the engineer.

"Work" —Work shall be understood to mean the furnishing of all labor,materials, equipment, and other incidentals necessary or convenient to the successful completion of the project or the portionof the project involved and the carrying out of all the dutiesand obligations imposed by the contract.

"Working Day"—Working day, a calendar day, exclusive of Sundays andlegal holidays, on which weather and working conditions permitthe contractor to make effective use of not less than 50 per centof the usual daily men hours during regular working hours.Saturday, subject to the above, shall be considered one-half a

working day, unless according to prevailing practice at thelocation of the project no work is done on Saturdays, in whichcase Saturday shall not be counted as a working day.

A. A. S. H. 0.—American Association of State Highway Officials.

A. S. T. M.—American Society for Testing Materials.

A. W. P. A.—American Wood Preservers Association.

A. W. S.—American Welding Society.

SECTION 2—Proposal Requirements and Conditions

1.2. 1.—Contents of Proposal Form.

Bidders will be furnished by the commission with proposal forms whichwill state the location and description of the work contemplated and whichwill show the approximate quantities of the work to be performed ormaterials to be furnished, the amount of the proposal guaranty, and thedate, time and place of filing and of opening proposals. The form willalso refer to any special provisions or requirements which vary from, or aresupplemental to, the standard specifications.

1. 2. 2.—Interpretation of Estimates.

The engineer's estimate of quantities as shown in the instructions tobidders or proposal shall be used as a basis of calculation upon which theaward of contract will be made, but these quantities are not guaranteed to beaccurate and are furnished without any liability on the part of the State.

1. 2. 3.—Examination of Plans, Specifications, and Site of the WorkBidders shall carefully examine the instructions to bidders, plans, speci

fications, special provisions, supplemental specifications and site of theproposed work in order to satisfy themselves by examination as to all localconditions affecting the contract and as to the detailed requirements ofconstruction.


1. 2. 4.—Preparation of Proposal.

Each proposal submitted shall be upon the form furnished. No otherproposal will be considered. The blank spaces must be filled in correctlyand the amounts written legibly.

The bidder shall sign the proposal on the blank space provided therefor.If the proposal is made by a partnership or corporation, the name andaddress of the partnership or corporation, as well as that of the agentacting therefor, shall be shown.

1. 2. 5.—Rejection of Proposals.

Proposals may be rejected if they show any alteration of form, additions not called for, conditional or alternate bids, irregularities of any kind,or if they contain a clause in which the bidder reserves the right to acceptor reject a contract awarded to him. Proposals in which the prices areobviously unbalanced may be rejected.

1. 2. 6.—Proposal Guaranty.

No proposal will be considered unless accompanied by a certified orcashier's check in the amount as specified in the proposal form and madepayable to the party specified. The full amount of the proposal guarantyshall be forfeited to the State, in liquidation of damages sustained, in theevent that the bidder (or bidders) fails to execute a satisfactory contractand file an acceptable contract bond within days after the acceptance of his proposal.

2. 2. 7.—Delivery of Proposal.

Each proposal submitted shall be sealed and plainly marked "Proposalfor Bridge Work. Located in ," and with the name and addressof the bidder on the outside of the envelope. When sent by mail, preferablyregistered, the sealed proposal, marked as indicated above, must be enclosedin an additional envelope. All proposals shall be filed prior to the time andat the place specified in the advertisement or instructions to bidders.

1. 2. 8.—Withdrawal of Proposal.

A bidder will be permitted to withdraw his proposal unopened afterit has been deposited if such request is received in writing prior to thetime specified for opening proposals.

1. 2. 9.—Public Opening of Proposals.

Proposals will be opened publicly and read at the time and placespecified in the advertisement.

1. 2. 10.—Disqualification of Bidders.

More than one proposal from an individual firm, partnership, corporation, or association under the same or different names will not be considered. Collusion between bidders will be sufficient cause for rejection of allbids so affected.

1. 2. 11.—Competency of Bidders.

Bidders must be capable of performing the various items of work bidupon. They may be required to furnish a statement covering experienceon similar work, list of machinery, plant and other equipment availablefor the proposed work, and such statements of their financial resources as

may be deemed necessary.

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SECTION 3 —Award and Execution of Contract

1. 3. 1.—Consideration of Bids.

The right is reserved to waive defects and to reject any or all proposals.

1. 3. 2.—Award of Contracts.

Contracts shall be awarded at the time and place indicated in theadvertisement, or as soon thereafter as practicable.

1. 3. 3.—Return of Proposal Guaranty.

The proposal guaranties of all except the three lowest bidders will be

returned promptly after the tabulation of bids has been made, and in nocase will a proposal guaranty be held longer than days withoutthe bidder's written consent. Should no award be made withindays, all proposals will be rejected and proposal guaranties returned.

1.3. 4.—Requirements of Contract Bond.

The successful bidder, within days from the date of acceptance of his proposal, shall furnish and file with the proper officer asdesignated in the advertisement or instructions to bidders, an acceptablebond in an amount not less than per cent of the contract amount.Such bond shall be on the form specified, and shall meet all requirementsas specified in the laws of .

Negotiable securities approved by the commission, in an amount equalto that specified above, may, at the option of the contractor, be depositedwith the commission in lieu of a bond.

1. 3. 5.—Execution of the Contract.

The individual, firm, or corporation to whom the contract has been

awarded shall execute and file with the commission copies of thecontract within days after the date of the award.

1. 3. 6.—Approval of Contract.

Contracts requiring execution by the commission shall be so executedbefore any construction work is started. Any material delivered or workstarted before such approval is noted on the contract is entirely at thecontractor's risk.

1. 3. 7.—Failure to Execute Contract.

Failure to execute a contract and file an acceptable bond as providedherein within days from date of award shall be just cause forthe annulment of the award and the forfeiture of the proposal guarantyto the State, not as a penalty but in liquidation of damages sustained.

SECTION 4—Scope of the Work

1. 4. 1.—Intent of the Plans and Specifications.

The true intent of the plans and these specifications is to provide forthe execution and completion in every detail of the work described herein,and it is understood that the contractor for all or any part will furnish alllabor, material, equipment, tools, transportation and necessary supplies,such as may reasonably be required to execute the contract in a satisfactoryand workmanlike manner and in accordance with the plans, specifications,


and terms of the contract. Any deviation from these requirements mustbe stipulated in the contract.

1. 4. 2.—Special Work.

Should any construction or conditions which are not covered by theplans or these specifications be anticipated, or encountered during construction, special provisions for such work will be prepared by the engineerand shall be considered a part of these specifications the same as thoughcontained fully herein.

2. 4. 3.— Increased or Decreased Quantities.

The right is reserved, without impairing the contract, to make suchincrease or decrease in the quantities of the work as may be considerednecessary to complete fully and satisfactorily the structures included inthe contract. The compensation to the contractor for such changes shallbe adjusted as provided herein.

1. 4. 4.—Extra Work.

The right is reserved, without impairing the contract, to order theperformance of such work, of a class not contemplated in the proposal, asmay be considered necessary to complete fully and satisfactorily the structures included in the contract. Such extra work shall be done by thecontractor and he shall be compensated as provided herein.

1. 4. 5.—Temporary Crossings and Detours.

The contractor will not be required to construct or maintain temporarycrossing structures unless such crossings are stipulated in the contract orordered as extra work by the engineer. If the building of a temporarycrossing is included in the contract the responsibility of the contractor foraccidents to the public or his workmen, arising from its construction ormaintenance, shall extend to such structure and its roadway approaches.

Whenever the road upon which construction is in progress is closed totraffic by order of the engineer, the contractor shall be relieved of allresponsibility in connection with the construction, protection, and maintenance of adequate detours, but he shall be responsible for the construction,maintenance, and protection of adequate barriers, watchmen, or red lightsat both ends of the portion of the road closed.

1. 4. 6.—Removal and Disposal of Structures and Obstructions.

The contractor shall remove at his expense any existing structure orpart of structure which interferes in any way with the new construction.

All structures and materials found on the work and not especiallyreserved in the plans or specifications shall be the property of the State,to be disposed of in the confines of the right of way as the engineer shalldirect. Unless otherwise provided, the material from any existing oldstructures may be used temporarily by the contractor in the erection of thenew structure. Such material shall not be cut or otherwise damaged, exceptwith the approval of the engineer.

1. 4. 7.—Rights in and Use of Materials Found on the Site.

The contractor may use in the construction of the work any suitablesand, gravel, or stone found in the excavation but, if necessary, shall replaceany material so removed with material satisfactory to the engineer.

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.1. 4. 8.—Final Cleaning Up.

Upon completion and before final acceptance, the contractor shallremove all falsework, excavated or useless materials, rubbish and temporarybuildings, replace or renew any fences damaged and restore in an acceptable manner all property, both public and private, which may have beendamaged during the prosecution of the work, and shall leave the bridgesite and adjacent highway in a neat and presentable condition satisfactoryto the engineer. All excavated material or falsework placed in the streamchannel during construction shall be removed by the contractor beforefinal acceptance.

SECTION 5—Control of the Work

1. S. 1.—Authority of Engineer.

The engineer shall decide any and all questions which may arise as tothe quality and acceptability of materials furnished and work performedand as to the manner of performance and rate of progress of the work,and shall decide all questions which may arise as to the interpretation ofthe plans and specifications, and all questions as to the acceptable fulfillmentof the terms of the contract.

2. 5. 2.—Plans and Working Drawings.

General drawings, showing such details as are necessary to give a

comprehensive idea of the construction contemplated, will be included inthe plans, but the contractor shall submit to the engineer for approval suchadditional stress sheets, shop details, or other working drawings as maybe required for the construction of any part of the work, and prior to theapproval of such plans any work done or material ordered shall be at thecontractor's risk.

Working drawings for steel structure shall consist of shop detail,

erection and other working plans showing dimensions, sizes of material,details and other information necessary for the complete fabrication anderection of the metal work.

Working drawings for concrete structures shall consist of such detailedplans as may reasonably be required for the successful prosecution of thework and which are not included in the plans furnished by the engineer.These may include plans for falsework, bracing, centering and form work,masonry lay-out diagrams, and diagrams for bent reinforcement.

It is expressly understood that the approval by the engineer of thecontractor's working drawings relates to the requirements for strength anddetail, and such approval will not relieve the contractor from responsibilityfor errors in dimensions.

The contractor shall furnish the engineer with such blueprint copiesof the working drawings as may be required for approval and construction purposes, and upon completion of the work, cloth tracings, if requiredshall be supplied to the engineer.

The contract price shall Include the cost of furnishing all workingdrawings, and the contractor will be allowed no extra compensation forsuch drawings.

1. S. 3.—Deviations from the Plans.

No deviation from the plans or the approved working drawings willbe permitted without the written order of the engineer.


1. 5. 4.—Coordination of Specifications and Plans.

In cases of conflict in the requirements and provisions as set out bythe general specifications, the plans, the supplemental specifications, theproposal form and the special provisions, it shall be understood that thespecial provisions including the proposal form take precedence over thesupplemental specifications and over both the plans and standard specifications and it shall also be understood that the supplemental specificationstake precedence over the standard specifications and that the plans takeprecedence over the standard specifications and the supplemental specifications. On all plans the figured dimensions shall govern in case of anydiscrepancy between the figured dimensions and the scaled dimensions.

The contractor shall take no advantage of any apparent error or omission in the plans or specifications, but the engineer shall be permitted tomake such corrections and interpretations as may be deemed necessary forthe fulfillment of the intent of the plans and specifications.

1. 5. 5.—Cooperation by Contractor.

The contractor shall conduct his operations so as to interfere as littleas possible with those of other contractors, subcontractors, or the publicon or near the work.

The contractor shall at all times during his absence from the workhave a competent superintendent or foreman capable of reading andthoroughly understanding the plans and specifications, as his agent on thework, who shall receive instructions from the engineer or his authorizedrepresentatives. The superintendent or foreman shall have full authorityto execute the orders or directions of the engineer without delay and topromptly supply such materials, tools, plant equipment, and labor as maybe required.

1. 5. 6.—Construction Stakes.

The general location, alignment, and elevation of each structure willbe determined by the engineer, but the contractor shall assume full responsibility for the alignment, elevation, and dimensions of each and all partsof the work and their mutual agreement. For all structures the engineershall furnish the contractor with roadway and waterway centerlines andsuch bench marks or other points as are necessary to lay out the workcorrectly. If requested by the contractor, the engineer shall furnish stakesdetermining the centerlines of all piers, pedestals, or abutments, togetherwith stakes determining the angles of the wings or retaining walls.

The contractor shall exercise proper care in the preservation of alignment, grade, and reference stakes, set for his use or that of the engineer.If such stakes are injured, lost or removed by the contractor's operationsthey shall be reset at his expense.

1. 5. 7.—Authority and Duties of Inspectors.

Inspectors shall be authorized to inspect all work done and all materialsfurnished. Such inspection may extend to all or any part of the work andto the preparation, fabrication or manufacture of the materials to be used.

Resident engineers and inspectors may be stationed on the work toreport to the engineer as to the progress thereof, and manner in which itis being performed, also to report whenever it appears that materials furnished or work performed by the contractor fail to fulfill the requirementsof the specifications and contract, and to direct the attention of the contractor to such failure. Such inspection shall not relieve the contractor

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from any obligations to furnish acceptable materials or to provide completedconstruction that is satisfactory in every particular. In case of any disputearising between the resident engineer or inspector and the contractor as tomaterial furnished or the manner of performing the work, the residentengineer or inspector shall have authority to reject materials or suspendthe work until the question at issue can be referred to and decided by theengineer. Neither the resident engineer nor inspector is authorized to revoke, alter, enlarge, relax or release any requirements of these specifications,nor to issue instructions contrary to the plans and specifications. Neitherthe resident engineer nor inspector shall act as foreman or perform otherduties for the contractor, nor interfere with the management of the workby the latter.

1. S. 8.—inspection.

The engineer or his representatives shall be allowed access to all partsof the work at all times and shall be furnished such information and assistance by the contractor as may be required to make a complete and detailedinspection. Such inspection may include mill, plant or shop inspection andany material furnished under these specifications is subject to suchinspection.

1.5.9.—Removal of Unauthorized and Defective Work.

Any defective work, whether the result of poor workmanship, use ofdefective materials, damage through carelessness, or of any other cause,found to exist prior to acceptance of or final payment for the work, shallbe removed immediately and replaced by work and materials which shallconform to the specifications, or shall be remedied otherwise in an acceptable manner authorized by the engineer. This clause shall have full effectregardless of the fact that the defective work may have been done or thedefective materials used with the full knowledge of the inspector. The factthat the inspector in charge may have previously overlooked such defectivework shall not constitute an acceptance of any part of it.

No work shall be done without lines and grades having been given bythe engineer. Work done contrary to or regardless of the instructions ofthe engineer, work done beyond the lines shown on the plans or as given,except as herein provided, or any extra work done without authority, will be

considered as unauthorized and will not be paid for under the provisionsof the contract. Work so done may be ordered removed or replaced at thecontractor's expense.

2. S. 10.—Final Inspection.

Unless otherwise provided, the engineer shall make final inspection ofeach structure included in the contract, within 10 days after notification bythe contractor that the work is completed. If the work is not acceptableto the engineer he shall advise the contractor as to the particular defects tobe remedied before final acceptance can be made.

2. S. 11.—Disputed Claims.

In any case where the contractor deems extra compensation to be due

him for work or materials not clearly covered in the contract, or not ordered

by the engineer as an extra, as defined herein, the contractor shall notifythe engineer of his intention to make claim for such extra compensation

before he begins the work on which he bases the claim. If such notificationis not given, or the engineer is not afforded proper facilities by the con


tractor for keeping strict account of actual cost, then the contractor herebyagrees to waive the claim for such extra compensation. Such notice by thecontractor, and the fact that the engineer has kept account of the cost asaforesaid, shall not in any way be construed as proving the validity of theclaim. The claim must be passed upon by the commission. In case theclaim is found to be just, it shall be allowed and paid as an extra asprovided herein for extra work.

1. 5. 12.—Arbitration.

Both parties to the contract agree that as a condition precedent to thefiling of an action in any court involving the amount or rate of paymentor settlement for work performed by the contractor under these specifications and contract, and as a condition precedent to the liability of the commission for any amount other than contained in the estimates approved b;

the engineer, any question at issue involving the amount or rate of settlement or liability of the State for an amount other than as shown by theestimates approved by the engineer, shall be referred to a board of arbitration for decision and award. Said board of arbitration shall consist ofthree persons, one to be chosen by the commission, one by the contractor,and the third by these two. The board of arbitration shall make such rulesas it shall determine equitable to govern itself in the conduct of the investigation and determination of the award. In determining the award, themajority of the board shall govern. Certified copies of the findings andaward shall be filed with the commission and contractor. The board ofarbitration shall fix the amount of the cost of the proceedings, includinga fair and reasonable compensation to the arbitrators, and shall determinehow the total cost shall be borne. The board of arbitration shall haveauthority only to pass upon questions involving compensation to the contractor for work actually performed but not allowed by the engineer, andits authority shall not extend to the interpretation of the plans and specifications or the determination of the qualities of materials or workmanshipfurnished, nor shall it have authority to set aside or modify the terms orrequirements of the contract.

SECTION 6—Control of Materials

2. 6. 1.—Source of Supply and Quality.

These specifications contemplate the use of first class materials throughout, used in such a manner as to produce completed construction which isworkmanlike and acceptable in every detail. Only materials conformingto the requirements of these specifications and approved by the engineeishall be used in the work. The source of supply of materials shall be

approved by the engineer before shipment is made.

1. 6. 2. —Test$ of Materials.

All tests of materials shall be made by the engineer in accordance withapproved methods as described and designated in these specifications.

When tests of materials are necessary, such tests shall be made by andat the expense of the commission unless otherwise provided. The contractor shall afford such facilities as the engineer may require for collecting and forwarding samples, and shall hold the materials represented bythe samples until tests have been made, and the materials found equalto the requirements of the specifications or to approved samples. Thecontractor in all cases shall furnish the required samples without charge.

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In the absence of any definite specification or reference to a specification given in the body of the general specifications, in the supplementalspecifications or in the special provisions for the particular project involved,

it shall be understood that such materials shall meet the requirements ofthe Standard Specifications for Highway Materials of the American Asso

ciation of State Highway Officials, or in the event that no specification has

been officially adopted by said Association, such materials shall meet the

specifications and requirements of the American Society for TestingMaterials.

Unless otherwise specified, all tests of materials shall be made in

accordance with the "Methods of Sampling and Testing" prescribed by the

American Association of State Highway Officials, or in case no method has

been prescribed by this Association, said tests shall be conducted in accord

ance with methods prescribed by the American Society for Testing Materials.Whenever in these specifications a particular specification of the Ameri

can Association of State Highway Officials or the American Society forTesting Materials is referred to by number, it shall be understood that such

reference shall include all amendments and additions thereto adopted by

such organizations prior to the call for bids.

1. 6. 3.—Storage of Materials.

Materials shall be stored so as to insure the preservation of theirquality and fitness for the work. Stored materials shall be located so asto facilitate prompt inspection. That portion of the right of way notrequired for public travel may be used for storage purposes and for theplacing of the contractor's plant and equipment. Owners of abuttingproperty shall be permitted access thereto at all times. Additional spacerequired, unless otherwise stipulated, shall be provided by the contractorat his expense.

2. 6. 4.—Defective Materials.

All materials not conforming to the requirements of these specificationsshall be considered as defective. No defective material, the defects of whichhave been subsequently corrected, shall be used until approval has beengiven. Upon failure on the part of the contractor to comply forthwith withany order of the engineer made under the provisions of this article, theengineer shall have authority to remove and replace defective material andto deduct the cost of removal and replacement from any moneys due or tobecome due the contractor.

1.6. 5.—Silence of Specifications.

The apparent silence of specifications, plans, special provisions andsupplemental specifications as to any detail or the apparent omission fromthem of a detailed description concerning any point shall be regarded asmeaning that only the best general practice is to prevail and that onlymaterial and workmanship of first quality are to be used. All interpreta-tations of these specifications shall be made upon the basis above stated.

SECTION 7—Legal Relations and Responsibility to Public

2. 7. 2.—Laws to be Observed.

The contractor is presumed to be familiar with all laws, ordinancesand regulations which may in any manner affect the equipment or materialsused in the proposed construction, those engaged on the work, or the conduct


of the work, and shall save the State and its representatives harmlessagainst any claim arising from violation thereof.

1. 7. 2.—Permits and Licenses.

The contractor shall procure all permits and licenses, pay all chargesand fees, and give all notices necessary and incident to the due and lawfulprosecution of the work.

I. 7. 3.—Patented Processes and Materials.

The contractor assumes the responsibility of defending any and allsuits brought for the infringement of any patent claimed to be infringedby any material or process not required to be used but which he may electto use in the construction of any structure provided for in the plans furnished by the State, and to hold the State harmless on account of suchsuits or claims.

The contractor must assume all responsibility for plans submitted byhim for the use of the State and shall hold the State harmless from anysuit, royalty or damage on account of the infringement of any patent bysaid plans.

Plans not supplied by the State which embody the use of any patentedprocess or design shall be accompanied by a written statement of the exactterms under which said plans are to be used, and shall provide a definiteand fixed price for which any responsible contractor may use said plans,processes or designs without further liability of any character.

1. 7. 4.—Federal Participation.

The attention of the contractor is called to the fact that, when theUnited States Government pays all or any portion of the cost of the work,the Federal laws authorizing such participation and the rules and regulations made pursuant to such laws must be observed by the contractor. Thework shall be subject to the inspection and approval of the representativesof such Federal agencies as are created for the administration of these laws.

1. 7. 5.—Sanitary Provisions.

The contractor shall observe all rules and regulations of the State orlocal health officials, and must take such precautions as are necessary toavoid creating unsanitary conditions.

1. 7. 6. —Public Safety and Convenience.

The contractor shall at all times so conduct his work as to insure theleast possible obstruction to traffic. The convenience of the general publicand the residents along the highway and the protection of persons andproperty are of prime importance and shall be provided for by the contractorin an adequate and satisfactory manner.

1.7. 7.—Barricades and Warning Signs.

The contractor shall at his expense and without further or other orderprovide, erect and maintain at all times during the progress or temporarysuspension of the work, suitable barricades, fences, signs, or other adequateprotection, and shall provide, keep and maintain such danger lights, signals,and watchmen as may be necessary or as may be ordered by the engineerto insure the safety of the public as well as those engaged in connection withthe work. All barricades and obstructions shall be protected at night byred signal lights which shall be suitably distributed across the roadway and

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which shall be kept burning from sunset to sunrise. Barricades shall be ofsubstantial construction and shall be painted white or whitewashed toincrease their visibility at night.

The contractor's responsibility for the maintenance of barricades andlights on any individual item of work included in the contract shall cease

when final estimate (not including suspended payments) on such items hasbeen allowed by the commission, or when specifically released in writing bythe engineer.

The engineer shall use every precaution possible to safeguard the persons and property of the traveling public, and to divert traffic from theroad on which construction work is in progress, but the failure of the engineer to notify the contractor to maintain barriers, lights, signals of watchmen, shall not operate to relieve the contractor from his responsibility.

J. 7. 8.—Protection and Restoration of Property.

The contractor shall not enter upon private property for any purposewithout obtaining permission and shall be responsible for the preservationof all public and private property, trees, monuments, etc., along and adjacent to the highway, and shall use every precaution necessary to preventdamage or injury thereto. He shall use suitable precautions to prevent, andshall be responsible for damage to pipes, conduits and water mains, andother underground structures, and shall carefully protect from disturbanceor damage all land monuments until these are properly referenced by theengineer.

1. 7. 9.—Responsibility for Damages.

The contractor shall assume all responsibility for damages sustainedby persons or property due to the carrying on of his work and until finalacceptance thereof or until released by the engineer in writing. He shallbe responsible for all accidents to persons or property, and shall save theState harmless from all damages resulting from any accidents which mayoccur on existing structures to be replaced by new construction under thecontract after the date of completion as specified therein. Any extensionof time granted the contractor in which to complete the contract shall notrelieve him or his surety from this responsibility.

1. 7. 10.— Contractor's Responsibility for Work.

Until final acceptance of the structure the contractor shall be heldresponsible for any injury or damage to the structure or to any part thereofby the action of the elements, or from any cause whatsoever, whether arising from the execution or from the non-execution of the work, and he shallmake good at his own expense all injuries or damages to any portion of thestructure before its completion and final acceptance.

I. 7. 11.—Personal Liability of Public Officials.In carrying out any of the provisions of this contract or in exercising

any power or authority granted to him thereby there shall be no personalliability upon the engineer or his authorized assistants, it being understoodthat in such matters he acts as the agent and representative of the State.

1. 7. 12 No Waiver of Legal Rights.

The State shall not be precluded or estopped by any measurement,estimate, or certificate made either before or after the completion andacceptance of the work and payment therefor from showing the true amount


and character of the work performed and materials furnished by the contractor, or from showing that any such measurement, estimate, or certificateis untrue or incorrectly made, or that the work or materials do not conformin fact to the contract. The State shall not be precluded or estopped, notwithstanding any such measurement, estimate or certificate, and paymentin accordance therewith, from recovering from the contractor and suretiessuch damages as it may sustain by reason of his failure to comply with theterms of the contract. Neither the acceptance by the commission, or by anyrepresentative of the commission, nor any payment for nor acceptance ofthe whole or any part of the work, nor any extension of time, nor anypossession taken by the commission, shall operate as a waiver of any portionof the contract or of any power herein reserved, or any right to damageherein provided. A waiver of any breach of the contract shall not be heldto be a waiver of any other or subsequent breach.

SECTION 8—Prosecution and Progress

2. 8. 1.—Subletting or Assignment of Contract.

The contractor shall not sublet, sell or assign all or any portion of thecontract, or the work provided therein without the written consent of thecommission.

1. 8. 2.—Prosecution of the Work.

The execution of works under this contract shall not be commenceduntil the contractor has received a written order to that effect, signed bythe engineer, and the work shall thereupon be at once begun and continuously carried on to completion, subject to such suspensions as are providedfor herein.

The progress of the work shall be at a rate sufficient to complete thecontract in an acceptable manner within the period of time specified. Theengineer shall at frequent intervals make progress reports to the commission, and if it appears that the rate of progress is such that the contractwill not be completed within the time limit, or if the contract is not beingexecuted in a satisfactory and workmanlike manner, the commission mayorder the contractor to take such steps as it considers necessary to completethe contract within the period of time provided, or to prosecute the workin a satisfactory manner.

2. 8. 3.—Limitations of Operations.

The contractor shall begin work at such points as the engineer maydirect or approve and shall thereafter prosecute the work at such pointsand in such order as may be prescribed or approved from time to time bythe engineer.

In the case of a dispute arising between two or more contractors engaged on the same work as to the respective rights of each under thesespecifications, the engineer shall determine the matters at issue and shalldefine the respective rights of the various interests involved, in order tosecure the completion of all parts of the work in general harmony and withsatisfactory results, and his decision shall be final and binding on all partiesconcerned.

2. 8. 4.— Character of Workmen and Equipment.

The contractor shall employ only competent and efficient laborers,mechanics, or artisans, and whenever, in the opinion of the engineer, any

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employe is careless or incompetent, or obstructs the progress of the work,or acts contrary to instructions, or conducts himself improperly, the contractor shall, upon complaint of the engineer, discharge or otherwise removehim from the work and not employ him again upon it.

The methods, equipment and appliances used on the work shall be suchas will produce a satisfactory quality of work and shall be adequate tocomplete the contract within the time limit specified.

1. 8. S.—Temporary Suspension of the Work.

The engineer shall have authority to suspend the work wholly or inpart for such period or periods as he may deem necessary, due to unsuitableweather or such other conditions as are considered unfavorable for theprosecution of the work, or for such time as is necessarily due to the failureon the part of the contractor to carry out orders given or to perform anyor all provisions of the contract.

When under suspension, the work shall be put in proper and satisfactory condition, carefully covered and properly protected, as directed by theengineer. In all cases of suspension of construction operations, the workshall not again be resumed until permitted by order of the engineer.

1. 8. 6.—Determination and Extension of Contract Time.

If the satisfactory execution of the contract shall require work ormaterials in greater amounts or quantities than those set forth on theplans, then the contract time may be increased by such an amount as maybe determined by the engineer. Extension to the contract time may be

granted for other reasons, at the discretion of the engineer. No allowanceshall be made for delay or suspension of the work due to the fault of thecontractor.

In contracts specifying a certain number of working days for completion, the number of working days shall be determined according to thedefinition of "working days" specified in section 1.

If for any reason beyond the control of the contractor the work shall

be delayed he may be granted an extension of time in the discretion of theengineer.

All requests for extension of time in which to perform the contractshall be submitted in writing by the contractor to the engineer.

1. 8. 7.—Failure to Complete on Time.

Should the contractor fail to complete the work within the required

time limit, subject to the modification of the preceding article, "Determination and Extension of Contract Time," the engineer will thereafterdeduct from any moneys due or coming due to the contractor as determinedby the engineer's estimates, an amount equal to the cost of maintaining thenecessary force of engineers and inspectors on the work plus the cost ofconstructing or maintaining detours around the work during the additionaltime, and this amount shall be considered as reasonable liquidated damagesdue to the State from the contractor for his failure to complete the contractwithin the specified time limits.

If the importance of any structure erected under these specificationsis such that the commission considers it advisable, there may be insertedin the contract, in lieu of the above, a stipulation for liquidated damages incertain specified and fixed amounts. When such a clause is inserted in thecontract, the State does not waive its right to collect all such additional


damages as it may sustain by a failure on the part of the contractor tocarry out the terms of this contract.

1. 8. 8.—Annulment of Contract.

If the contractor should fail to make satisfactory progress, or to com

ply with orders of the engineer, or should he neglect or refuse to removematerials, or to perform anew such work as has been rejected as defectiveand unsuitable, or if the contractor shall become insolvent or be declaredbankrupt, or shall make an assignment for the benefit of creditors, or fromany other cause shall not carry on the work in an acceptable manner, thecommission shall have the right to annul its contract without process oraction at law, and to turn over to the surety for completion or, at its option,or in case performance is guaranteed by negotiable securities, to take overthe work and complete it, either by day labor or by the reletting of all orany part of the work. The contractor upon receiving notice to this effectshall vacate possession and give up the said work, or the parts thereofspecified in said notice, peaceably to the engineer. All material, plant,caissons, cofferdams, piling, sheeting, formwork, scaffolding, pumps,dredges and other erection appliances, and the plans thereof, shall, at theoption of the engineer, remain on the work until completed, at such rental(if any) as the engineer may consider reasonable. Neither by the takingover of the work by the commission, nor by the annulment of the contractshall the State forfeit the right to recover damages from the contractoror his surety for failure to complete his contract. Should the cost of completing the work by day labor or by reletting the same be in excess of theoriginal contract price, the contractor and his surety, if any, shall be heldresponsible for such excess cost.

2. 8. 9.—Termination of Responsibility.

The contract shall be considered as complete after all work includedhas been accepted by the commission, and the contractor shall be releasedfrom all further obligation except as to the conditions and requirements setforth in his bond.

1.8.10.—Compensation for Unreasonable Delays.

If unreasonable delays occur in reaching a settlement with the contractor on changes made in the plans or specifications, due to a failure ofthe engineer to act, or if there are delays due to a failure to provide thenecessary stakes after a 48-hour notice in writing to the engineer that suchstakes are needed, the contractor shall be compensated for any actual losson his payrolls or on materials.

SECTION 9—Measurement and Payment

2. 9. 1.—Measurements of Quantities.

All work completed under the contract shall be measured by the engineer according to United States standard measures.

1. 9. 2.—Scope of Payment.

The contractor shall accept the compensation, as herein provided, infull payment for furnishing all materials, labor, tools and equipment, andfor performing all work under the contract; also for all loss or damage

22 HIGHWAY BRIDGES

arising from the nature of the work, or from the action of the elements,or from any unforeseen difficulties which may be encountered during theprosecution of the work, until its final acceptance by the commission.

I. 9. 3.—Payments for Increased or Decreased Quantities.

It is mutually agreed that due to latent and/or unforeseen conditions,adjustments of plans to field conditions which cannot be foreseen at thetime of advertising, will be necessary during construction, and it is therefore of the essence of the contract to recognize such changes in the plansas constituting a normal and expected margin of adjustment, not unusualand not involving nor permitting change or modification of contract prices,provided only that resulting overruns or underruns from the quantities inthe bid schedule do not exceed a reasonable percentage.

A reasonable percentage shall be construed to apply to changes involving any major item to the amount of 25 per cent or less, of the quantitieslisted in the bid schedule, in which case payment will be made for the revisedquantities at the original contract bid unit price.

In case any change involves overruns or underruns of more than 25

per cent each of any major item, such change shall require a negotiatedchange-order or supplemental agreement, signed by both parties, settingforth the necessity for the change and an adjustment of unit price or pricesof the major items involved, and agreed upon as satisfactory to both parties.

A major item shall constitute any item, unless otherwise indicated onthe plans or designated in the special provisions, the contract price forwhich amounts to 5 per cent or more of the total contract price.

1. 9. 4.—Payments for Extra and Force Account Work.

In the event of any extra work being ordered by the engineer of a

class not covered by the prices submitted in the proposal, the basis of payment for the same shall be agreed upon in writing between the parties tothe contract before such work is done, or where such method of paymentcannot be agreed upon prior to beginning the work, the engineer may orderthe contractor to do such work on a "force account" basis.

All work done on a "force account" basis will be paid for in full in thefollowing manner:

(1) For all labor, teams, and foremen in direct charge of the specificoperation, including workmen's compensation and liability insurance on thesame, the contractor shall receive the current rate of wage for each andevery hour said labor, teams and foremen are actually engaged in suchwork, to which shall be added an amount equal to 15 per cent of the sumthereof.

(2) For all materials entering permanently into the work the contractor shall receive the actual cost of such materials, including freightcharges, as shown by original receipted bills, to which cost shall be addedan amount equal to 10 per cent of the sum thereof.

(3) For any machinery or special equipment, other than small toolsand including fuel and lubricants, which it may be deemed necessary ordesirable to use, the contractor shall be allowed a reasonable rental charge,to be agreed upon in writing before the work is begun, for each and everyday such machinery is in use upon such work, and to which sum no percentage shall be added.

The compensation herein provided shall be received by the contractoras payment in full for extra work done on the "force account" basis and


shall include superintendence, overhead and profit. For all work done on

the "force account" basis the contractor shall furnish certified copies ofthe payroll on itemized forms provided for that purpose, invoices of allmaterial and such other detailed information as may be required by theengineer.

J. 9. 5.—Payment for Omitted Items.

The commission shall have the right to cancel the portions of the contract relating to the construction of any item therein by the payment tothe contractor of a fair and equitable amount covering all items of costincurred prior to the date of cancellation or suspension of the work byorder of the engineer. The contractor shall be allowed to profit percentageon the materials used and construction work actually performed at ratesas provided under "Payment for Extra and Force Account Work," but noallowance will be made for anticipated profits. Acceptable materials orderedby the contractor or delivered on the work prior to the date of cancellationor suspension of the work by order of the engineer shall be purchased fromthe contractor by the State at actual cost and shall thereupon become theproperty of the State.

2. 9. 6. —Partial Payments.

If there is a sufficient amount of work in the contract to extend overa period of more than one month, the contractor shall receive monthlyestimates based on the proportion of the contract completed and acceptableto the engineer and any fabricated steel or other finished material delivered.No partial payment will be allowed on cement or concrete aggregates. Suchestimates shall not be for sums of less than one thousand dollars. The contractor agrees that the allowance of a monthly estimate by the commissiondoes not constitute final acceptance of the work. Each consecutive estimateshall be filed by the contractor as a claim against the State and certifiedto by the engineer, and 10 per cent of each estimate, plus the amount ofany unsatisfied claims filed against the contractor for labor or materials,shall be deducted and held until final acceptance of the entire contractexcept as provided herein. The monthly payments shall be considered asapproximate only, and before the final estimate is allowed and final acceptance made on this contract, the commission may require the contractor tofurnish a list of all persons furnishing labor or materials, with satisfactoryevidence that such persons have been paid in full. Should a reasonabledoubt arise during construction as to the adequacy of any part of the completed work, the estimate for that portion shall not be allowed until thecause for such doubt has been removed.

Unless otherwise provided, each structure must be passed upon by theengineer within 10 days after written notice by the contractor that thework is completed. Where more than one structure is included in the contract 90 per cent of the contract price for each structure shall become dueupon final acceptance of that structure by the commission. The remaining10 per cent of the contract price shall be retained by the State until finalacceptance by the commission of all of the work included in the contract.If the total amount of the retained percentage is greatly in excess of theuncompleted and unaccepted portion of the contract, the commission may,upon recommendation of the engineer, allow the contractor a portion ofthis suspended payment, providing the commission shall at all times retainan amount sufficient to enable the State to complete the unaccepted oruncompleted work in the contract.

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I. 9. 7.—Acceptance and Final Payment.

Final acceptance is stipulated to mean final acceptance by the engineerand commission, or the allowance of final estimates by the commission.

When the work is completed the engineer shall certify to the commissionin writing that the contract is completed in whole, and shall further certifyas to the amount of work performed and as to the value thereof; the commission shall, upon receipt of such certificate, certify the aforesaid certificate or estimate for final payment, and shall notify the contractor andhis surety of the completion of the contract. The action of the engineerby which the contractor is bound, according to the terms of the contract,shall be evidenced by the aforesaid certificate and final payment, priorcertificates or estimates upon which payments may have been made beingmerely partial estimates and subject to correction in the final payment.

DIVISION II

Construction

SECTION I— Excavation and Fill

2. 1. 1.—General,

Foundation excavation shall include the removal of all material, ofwhatever nature, necessary for the construction of foundations and substructures in accordance with the plans or as directed by the engineer. Itshall include the furnishing of all necessary equipment and the constructionof all cribs, cofferdams, caissons, unwatering, etc., which may be necessaryfor the execution of the work. It shall also include the subsequent removalof cofferdams and cribs and the placement <>f all necessary backfill as hereinafter specified. It shall also include the wasting of excavated material,which is' not required for backfill, in a manner and in locations so as not toaffect the carrying capacity of the channel and not to be unsightly.

Compensation for all clearing and grubbing contained within the areadefined by lines connecting the extremities of the substructure units, regardless of whether or not excavation is involved, shall, unless otherwisespecified in the contract, be included in the unit price bid for excavation.

All substructures, where .practicable, shall be constructed in openexcavation and, where necessary, the excavation shall be shored, bracedor protected by cofferdams in accordance with approved methods. Whenfootings can be placed in the dry without the use of cribs or cofferdams,backforms may be omitted with the approval of the engineer and the entireexcavation filled with concrete to the required elevation of the top of thefooting. The additional concrete required shall be placed at the expenseof the contractor.

2. 1. 2.—Preservation of Channel.

Unless otherwise specified, no excavation shall be made outside ofcaissons, cribs, cofferdams, steel piling or sheeting, and the natural streambed adjacent to the structure shall not be disturbed without permissionfrom the engineer. If any excavation or dredging is made at the site ofthe structure before caissons, cribs or cofferdams are sunk or in place, thecontractor shall, without extra charge, after the foundation base is in place,backfill all such excavation to the original ground surface or river bed withmaterial satisfactory to the engineer. Material deposited within the streamarea from foundation or other excavation or from the filling of cofferdamsshall be removed and the stream area freed from obstruction thereby.

2. I. 3.—Depth of Footings.

The elevation of the bottoms of footings, as shown on .the plans, shallbe considered as approximate only and the engineer may order, in writing,such changes in dimensions or elevation of footings as may be necessaryto secure a satisfactory foundation.

2. 1. 4.—Preparation of Foundations for Footings.

All rock or other hard foundation material shall be freed from all loosematerial, cleaned and cut to a firm surface, either level, stepped, or roughened, as may be directed by the engineer. All seams shall be cleaned out andfilled with concrete, mortar or grrout.

When masonry is to rest on an excavated surface other than rock.

25

26 HIGHWAY BRIDGES

special care shall be taken not to disturb the bottom of the excavation andthe final removal of the foundation material to grade shall not be made untiljust before the masonry is to be placed.

2. J. 5.—Cofferdams and Cribs.

(a) General.

Cofferdams and cribs for foundation construction shall be carried toadequate depths and heights, be safely designed and constructed, and bemade as water-tight as is necessary for the proper performance of the workwhich must be done inside them. In general, the interior dimensions ofcofferdams and cribs shall be such as to give sufficient clearance for theconstruction of forms and the inspection of their exteriors, and to permitpumping outside of the forms. Cofferdams or cribs which are tilted or movedlaterally during the process of sinking shall be righted, reset or enlargedso as to provide the necessary clearance and this shall be at the sole expenseof the contractor.

When conditions are encountered which, in the opinion of the engineer,render it impracticable to unwater the foundation before placing masonry,he may require the construction of a concrete foundation seal of suchdimensions as may be necessary. The foundation shall then be pumpedout and the balance of the masonry placed in the dry. When weightedcribs are employed and the weight is utilized to partially overcome thehydro-static pressure acting against the bottom of the foundation seal,special anchorage such as dowels or keys shall be provided to transfer theentire weight of the crib into the foundation seal. During the placing of afoundation seal, the elevation of the water inside the cofferdam shall becontrolled to prevent any flow through the seal and if the cofferdam is toremain in place, it shall be vented or ported at low water level.

(b) Protection of Concrete.Cofferdams or cribs shall be constructed so as to protect green concrete

against damage from a sudden rising of the stream and to prevent damage to the foundation by erosion. No timber or bracing shall be left incofferdams or cribs in such a way as to extend into the substructure masonry, without written permission from the engineer.

(c) Drawings Required.For substructure work, the contractor shall submit, upon request, draw

ings showing his proposed method of cofferdam construction and otherdetails left open to his choice or not fully shown on the engineer's drawings.Such drawings shall be approved by the engineer before construction isstarted on work governed by them.

(d) Removal.

Unless otherwise provided, cofferdams or cribs with all sheeting andbracing shall be removed after the completion of the substructure, carebeing taken not to disturb or otherwise injure the finished masonry.

2. 1. 6.—Pumping.

Pumping from the interior of any foundation enclosure shall be donein such manner as to preclude the possibility of the movement of waterthrough any fresh concrete. No pumping will be permitted during theplacing of concrete or for a period of at least 24 hours thereafter, unlessit be done from a suitable sump separated from the concrete work by awater-tight wall or other effective means.

CONSTRUCTION 27

Pumping to unwater a sealed cofferdam shall not commence until theseal has set sufficiently to withstand the hydrostatic pressure.

2. I. 7.—Inspection.

After each excavation is completed, the contractor shall notify the engineer, and no masonry shall be placed until the engineer has approved thedepth of the excavation and the character of the foundation material.

2. 1. 8.—Back-fill.

All material used for back-fill shall be of a quality acceptable to theengineer and shall be free from large or frozen lumps, wood, or other extraneous material.

All spaces excavated and not occupied by abutments, piers, or otherpermanent work shall be refilled with earth up to the surface of the surrounding ground, with a sufficient allowance for settlement. All back-fillshall be thoroughly compacted and, in general, its top surface shall be

neatly graded.

The fill behind abutments and wing walls of all bridge structures shallbe deposited in horizontal layers not to exceed 12 inches in thickness andwell compacted. The back-fill in front of such units shall be placed firstto prevent the possibility of forward movement. Special precautions shallbe taken to prevent any wedging action against the masonry, and the slopebounding the excavation for abutments and wing walls shall be destroyedby stepping or roughening to prevent wedge action. Jetting of the fill behind abutments and wing walls shall not be permitted.

Fill placed around culverts and piers shall be deposited on both sidesto approximately the same elevation at the same time.

Adequate provision shall be made for the thorough drainage of all backfilling. French drains shall be placed at weep holes.

No back-fill shall be placed against any masonry abutment, wing wallor culvert until permission shall have been given by the engineer and preferably not until the masonry has been in place 14 days, or until test cylinder?show the strength to be twice the working stress used in the design.

Back-filling of sectional plate pipes and arches shall be done in accordance with articles 2. 23. 5. and 2. 23. 6.

2. 1. 9.—Filled Spandrel Arches.

For filled spandrel arches, the filling shall be carefully placed in suchmanner as to load the ring uniformly and symmetrically. The filling material shall be acceptable to the engineer and shall be placed in horizontallayers, not to exceed 12 inches in thickness, carefully tamped and broughtup simultaneously from both haunches. Wedge shaped sections of fillingmaterial against spandrels, wings or abutments will not be permitted.

2. 1. 10.—Approach Embankment.

When the contract for any bridge structure requires the placement ofapproach embankments, they shall be constructed and paid for in accordancewith the highway specifications governing this class of construction.

2. 1. 11.—Classification of Excavation.

Classification, if any, of excavation will be indicated on the plans andset forth in the proposal.

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2.1. 12.—Measurement and Payment.

Payment for foundation excavation shall include the cost of all labor,material, equipment, and other items that may be necessary or convenientto the successful completion of the excavation to the elevation of the bottom of the footings. It shall also include the cost of removing cofferdamsand any surplus material which may have been thrown up during the process of excavation, and shall include the cost of back-filling in a compactedcondition an amount of material equal to the amount of excavation. Anyback-fill required in excess of the amount excavated shall be paid for as

extra work unless a price for extra back-fill is included in the contract.The yardage to be paid for shall be the actual number of cubic yards in

original position, of material acceptably excavated in conformity with theplans or as directed by the engineer, but no yardage shall be included inthe measurement for payment which is outside of a volume bounded byvertical planes 18 inches outside of and parallel to the neat lines of thefooting. The cross-sectional area measured shall not include water or otherliquids, but shall include mud, muck and other similar semi-solids. The topand bottom limits of computed volume shall be the original ground surfaceand the bottom of the completed footing.

When it is necessary, in the opinion of the engineer, to carry thefoundations below the elevations shown on the plans, the excavation forthe first three feet of additional depth will be included in the quantity forwhich payment will be made under the item Foundation Excavation. Excavation below this additional depth will be paid for as extra work, unlessthe contractor is willing to accept payment at contract prices.

SECTION 2—Sheet Piles

2. 2. 1 General.

This specification covers only sheet piling shown on the plans, or ordered by the engineer, to be left in place so that it becomes a part of thefinished structure.

2. 2. 2 Timber Sheet Piles.

The timber, unless otherwise definitely noted upon the plans or in thespecifications, may consist of any species which will satisfactorily standdriving. It shall be sawn or hewn with square corners and shall be freefrom worm holes, loose knots, wind shakes, decayed or unsound portions, orother defects which might impair its strength or tightness.

The piles shall be of the dimensions shown on the plans either cut fromthe solid material or made by building up the piles of three planks securelyfastened together. The piles shall be drift sharpened at their lower ends so

as to wedge the adjacent piles tightly together.

The tops of the piles shall be cut off to a straight line at the elevationindicated and shall be braced with waling strips, properly lapped and joinedat all splices and corners. The wales shall preferably be in one lengthbetween corners and shall be bolted near the tops of the piles.

2. 2. 3.—Concrete Sheet Piles.

Where concrete sheet piles are required, they shall be in strict accordance with the detailed design. The requirements governing the manufacture and installation of concrete sheet piling shall conform, in general,to those governing precast concrete bearing piles.

CONSTRUCTION 29

2. 2. 4 Sleet Sfceef Piles.

Steel sheet piles shall be of the type and weight indicated on the plansor designated in the special provisions and of the material required indivision IV. The piles, when in place in the completed structure, shall be

practically water-tight at the joints. Painting of steel sheet piles shallconform to article 2. 3. 17.

2. 2. 5.—Measurement and Payment.

Payment for sheet piles shall include the cost of furnishing, driving andcutting off. Payment will be made on the basis of the piles driven as approved by the engineer, except that a deduction from the payment will be

made in an amount equal to the salvage value of the material cut off afterdriving.

Timber, concrete, and steel sheet piles will be paid for at the contractprice per square foot.

SECTION 3—Bearing Piles

2. 3. 1.—Materials.

Materials for piles shall conform to the requirements of division IV.

2. 3. 2.—Design and Conditions of Use.

General and Design: Refer to division III, section 5.Bearing Values, Design : Refer to article 3. 4. 17.Preservative Treatment : Refer to division II, section 21.

2. 3. 3.—Preparation for Driving.

(a) Excavation. •

In general, piles shall not be driven until after the excavation is complete. Any material forced up between the piles shall be removed to correctelevation without cost to the Commission before masonry for the foundationis placed.

(b) Caps.The heads of all concrete piles, and the heads of timber piles, when

the nature of the driving is such as to unduly injure them, shall be protected by caps of approved design, preferably having a rope or other suitable cushion next to the pile head and fitting into a casting which in turnsupports a timber shock block. When the area of the head of any timberpile is greater than that of the face of the hammer, a suitable cap shallbe provided to distribute the blow of the hammer throughout the crosssection of the pile and thus avoid, as far as possible, the tendency to splitor shatter the pile.

For special types of piling, driving heads, mandrels, or other devices inaccordance with the manufacturers' recommendation shall be provided so

that the pile may be driven without injury.For steel piling the heads shall be cut squarely and a driving cap shall

be provided to hold the axis of the pile in line with the axis of the hammer.

(c) Collars.Collars, bands, or other devices, to protect timber piles against splitting

and brooming shall be provided where necessary.

(d) Pointing.Timber piles shall be pointed where soil conditions require it. When

necessary, the piles shall be shod with metal shoes of a design satisfactory

30 HIGHWAY BRIDGES

to the engineer, the points of the piles being carefully shaped to secure aneven and uniform bearing on the shoes.

(e) Splicing Pilet.Full length piles shall be used where practicable. In exceptional cir

cumstances splicing of piles may be permitted. The method of splicing shallbe as shown on the plans or as approved by the engineer. When the splicing of steel piles or steel shells of special piles is done by welding, the arcmethod shall be given preference.

(f) Painting Steel Pilet.Steel piles shall be painted as specified in article 2. 3. 17.

2. 3. 4.—Methods of Driving.

(a) General.Piles may be driven with a gravity hammer, a steam hammer, or a

combination of water jets and hammer but a steam hammer is preferred.Precast concrete piles, preferably, shall be driven by means of a combination of hammer and jet.

(b) Hammers for Timber and Steel Piles.Gravity hammers for driving timber and steel piles shall weigh not less

than 2,000 pounds, preferably not less than 3,000 pounds and in no case shallthe weight of the hammer be less than the combined weight of driving headand pile. The fall shall be so regulated as to avoid injury to the piles and inno case shall exceed 15 feet. When a steam hammer is used, the totalenergy developed by the hammer shall be not less than 6,000 foot pounds perblow.

fe) Hammers for Concrete Piles.Unless otherwise provided, concrete piles, precast, or shells for cast-in-

place piles, shall be driven with a steam hammer which shall develop anenergy per blow at each full stroke of the piston, of not less than one footpound for each pound of weight driven. In no case shall the total energydeveloped by the hammer be less than 6,000 foot-pounds per blow. If a

gravity hammer is used, it shall have a weight not less than that of thedriving head and pile, and the maximum drop shall not exceed 8 feet.

(d) Additional Equipment.In case the required penetration is not obtained by the use of a hammer

complying with the above minimum requirements, the contractor shall provide a heavier hammer, or resort to jetting at his own expense.

(e) Leads.Pile driver leads shall be constructed in such a manner as to afford

freedom of movement of the hammer, and they shall be held in position byguys or stiff braces to insure support to the pile during driving. Exceptwhere piles are driven through water, the leads, preferably, shall be ofsufficient length so that the use of a follower will not be necessary.

Preferably, inclined leads shall be used in driving battered piles.

(f) Followers.The driving of piling with followers shall be avoided if practicable and

shall be done only under written permission of the engineer. When followers are used, one pile from every group of 10 shall be a long pile drivenwithout a follower, and shall be used as a test pile to determine the averagebearing power of the group.

CONSTRUCTION 81

(g) Water Jets.When water jets are used, the number of jets and the volume and

pressure of water at the jet nozzles shall be sufficient to freely erode thematerial adjacent to the pile. The plant shall have sufficient capacity todeliver at all times at least 100 pounds per square inch pressure at two%-inch jet nozzles. Before the desired penetration is reached, the jets shallbe withdrawn and the piles shall be driven with the hammer to secure thefinal penetration.

(h) Accuracy of Driving.Piles shall be driven with a variation of not more than % inch per

foot from the vertical or from the batter shown on the plans, except thatpiles for trestle bents shall be so driven that the cap may be placed in itsproper location without inducing excessive stresses in the piles, and foundation piles shall not be out of the position shown on the plan more than 6

inches after driving.

2. 3. 5.—Defective Piles.

The procedure incident to the driving of piles shall not subject themto excessive and undue abuse producing crushing and spalling of the concrete, injurious splitting, splintering and brooming of the wood or deformation of the steel. Manipulation of piles to force them into proper positionconsidered by the engineer to be excessive will not be permitted. Any piledamaged by reason of internal defects, or by improper driving or driven outof its proper location or driven below the elevation fixed by the plans orby the engineer, shall be corrected at the contractor's expense by one ofthe following methods approved by the engineer for the pile in question :

(1) The pile shall be withdrawn and replaced by a new and if necessary, a longer pile.

(2) A second pile shall be driven adjacent to the defective or low pile.(3) The pile shall be spliced or built up as otherwise provided herein

or a sufficient portion of the footing extended to properly embed the pile.Timber piles shall not be spliced without specific permission of the engineer.All piles pushed up by the driving of adjacent piles or by any other causeshall be driven down again.

2. 3. 6.—Determination of Bearing Values. (See also Article 3. 4. 17.)

(a) Loading Test*.

When required, the size and number of piles shall be determined byactual loading tests. In general, these tests shall consist of the applicationof a test load placed upon a suitable platform supported by the pile, withsuitable apparatus for accurately measuring the test load and the settlement of the pile under each increment of load.

In lieu thereof hydraulic jacks with suitable yokes and pressure gagesmay be used.

The safe allowable load shall be considered as 50 per cent of that loadwhich, after a continuous application of 48 hours, produces a permanentsettlement not greater than % inch measured at the top of the pile. Thismaximum settlement shall not be increased by a continuous application ofthe test load for a period of 60 hours or longer. At least one pile for eachgroup of 100 piles shall be tested.

(b) Timber Pile Formulas.In the absence of loading tests, the safe bearing values for timber piles

shall be determined by the following formulas :

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P =2WH

-for gravity hammers,

P =

S+1.02WH

•for single-acting steam hammers,

P =

S+0.12H (W+Ap)

for double-acting steam hammers,S+0.1

where P=safe bearing power in pounds,W = weight, in pounds, of striking parts of hammer,H = height of fall in feet,A = area of piston in square inches,p = steam pressure in pounds per square inch at the hammer,S =the average penetration in inches per blow for the last 5

to 10 blows for gravity hammers and the last 10 to 20blows for steam hammers.

The above formulas are applicable only when —<1) The hammer has a free fall.(2) The head of the pile is not broomed or crushed.(3) The penetration is reasonably quick and uniform.(4) There is no sensible bounce after the blow.(5) A follower is not used.

Twice the height of the bounce shall be deducted from "H" to determineits value in the formula.

Unless otherwise ordered by the engineer timber piling shall be drivento the bearing value given on the plans or in the supplemental specifications.If bearing values are not given, timber piling shall be driven to a minimumvalue of twenty tons.

In case water jets are used in connection with the driving, the bearing power shall be determined by the above formulas from the results ofdriving after the jets have been withdrawn, or a load test may be applied.

(c) Concrete and Steel Piles.When not driven to practical refusal the bearing value for concrete

and steel piles preferably shall be determined by means of loading testsabove specified. In the absence of loading tests, their safe bearing valuesmay be roughly approximated by the formulas specified for timber piles.However, the character of the soil penetrated, conditions of driving, distributions, sizes, lengths and weights of the piles, shells or cores driven, andthe computed load per pile shall be given due consideration in determiningthe probable safe bearing value of concrete and steel piles.

2. 3. 7.—Test Piles.When required, the contractor shall drive test piles of a length and at

the location designated by the engineer. These piles shall be of greaterlength than the length assumed in the design in order to provide for anyvariation in soil conditions.

2. 3. 8.—Order Lists for Piling.The contractor shall furnish piles in accordance with an itemized list,

which shall be furnished by the engineer, showing the number and lengthof all piles.

In determining lengths of piles for ordering and for footage to be included in the contract, the lengths given in the order list shall be based onthe lengths which are assumed to remain in the completed structure. Thecontractor shall, at his own expense, increase the lengths given to providefor fresh heading and for such additional length as may be necessary tosuit the contractor's method of operation.

CONSTRUCTION

2. 3. 9.—Storage and Handling of Timber Piles.

The method of storing and handling shall be such as to avoid injuryto the piles. Special care shall be taken to avoid breaking the surface oftreated piles and cant-hooks, dogs or pike-poles shall not be used. Cuts orbreaks in the surface of treated piling shall be given three brush coats ofhot creosote oil of approved quality and hot creosote oil shall be pouredinto all bolt holes.

2. 3. 10.—Cutting off Timber Piles.The tops of all piling shall be sawed to a true plane, as shown on the

plans, and at the elevation fixed by the engineer. Piles which support timber caps or grillage shall be sawed to conform to the plane of the bottomof the superimposed structure. In general, the length of pile above theelevation of cut-off shall be sufficient to permit the complete removal ofall material injured by driving, but piles driven to very nearly the cut-offelevation shall be carefully adzed or otherwise freed from all "broomed"splintered or otherwise injured material.

2. 3. 11.—Cutting off Steel or Steel Shell Piles.Piles shall be cut off at the required elevation. If capping is required

the connection shall be made according to details shown on the plans.

2. 3. 12.—Capping Timber Piles.

Timber piles not encased in concrete shall be protected as specifiedunder "Timber Structures."

2. 3. 13.—Manufacture of Precast Concrete Piles.

(a) General.Piles shall be constructed in accordance with details shown on the plans.

(b) Class of Concrete.Class A concrete shall be used for precast concrete piles.

(c) Form Work.Forms for precast concrete piles shall conform to the general require

ments for concrete form work as provided in division II under "ConcreteMasonry." Forms shall be accessible for tamping and consolidation of theconcrete. Under good weather curing conditions side forms may be removed at any time not less than 24 hours after placing the concrete, butthe entire pile shall remain supported for at least seven days and shallnot be subjected to any handling stress until the concrete has set for atleast 21 days and for a longer period in cold weather, the additional timeto be determined by the engineer.

(d) Reinforcement.Reinforcement shall be placed in accordance with details shown on the

plans.

(e) Casting.The piles may be cast in either a horizontal or a vertical position.

Special care shall be taken to place the concrete so as to produce satisfactorybond with the reinforcement and avoid the formation of "stone pockets,"honeycomb or other such defects.

To secure uniformity and remove surplus water, the concrete in eachpile shall be placed continuously and shall be compacted by vibrating or byother means acceptable to the engineer. The forms shall be overfilled, the

34 HIGHWAY BRIDGES

surplus concrete screeded off, and the top surfaces finished to a uniform,even texture similar to that produced by the forms.

(f) FinUh.As soon as the forms are removed, concrete piles shall be carefully

pointed with 1:2 mortar and finished. Trestle piling exposed to view shallbe finished above the ground line in accordance with the provisions governingthe finishing of concrete columns. Foundation piling, that portion of thetrestle piling which will be below the ground surface, and piles for use insea water or alkali soils shall not be finished except by pointing as aboveset forth.

(g) Curing.Concrete piles shall be cured as provided elsewhere in these specifi

cations for concrete. As soon as the piles have set sufficiently to permit,they shall be removed from the forms and piled in a curing pile separatedfrom each other by wood spacing blocks. No pile shall be driven until ithas set for at least 21 days and, in cold weather, for a longer period asdetermined by the engineer. Concrete piles for use in sea water or alkalisoils shall be cured for not less than 30 days before being used.

2. 3. 14.—Storage and Handling of Precast Concrete Pilet.Removal of forms, curing, storing, transporting and handling precast

concrete piles shall be done in such a manner as to avoid excessive bendingstresses, cracking, spalling or other injurious results. The method ofhandling shall not induce stresses in the reinforcement in excess of 12,000pounds per square inch, allowing 100 per cent of the calculated load forimpact and shock.

Piles to be used in sea water or in alkali soils shall be handled so as toavoid surface abrasions or other injuries exposing the interior concrete.

2. 3. 15.—Manufacture of Cast-in-Place Concrete Piles.

(a) General.

Piles shall be constructed in accordance with details shown on the plans.

(b) Inspection of Metal Shells.At all times prior to the placing of concrete in the driven shells, the

contractor shall have available a suitable light for the inspection of eachshell throughout its entire length. Any improperly driven, broken or otherwise defective shell shall be corrected to the satisfaction of the engineer,by removal and replacement, or the driving of an additional pile, at no extracost to the Commission.

(c) Class of Concrete.Class A concrete shall be used for cast-in-place piles.

(d) Reinforcement.Reinforcement shall be placed in accordance with the plans or supple

mental specifications.

(e) Placing Concrete.

No concrete shall be placed until all driving within a radius of 15 feethas been completed, nor until all the shells for any one bent have beencompletely driven. If this cannot be done, all driving within the abovelimits shall be discontinued until the concrete in the last pile cast has setat least seven days.

Concrete shall be placed as specified for piles precast in the vertical

CONSTRUCTION 35

position. Accumulations of water in the shells shall be removed before theconcrete is placed.

2. 3. 16.—Extensions or "Build-Vps."

Extensions, splices or "build-ups" on concrete piles, when necessary,shall be made as follows:

After the driving is completed, the concrete at the end of the pile shallbe cut away, leaving the reinforcing steel exposed for a length of 40 diameters. The final cut of the concrete shall be perpendicular to the axis ofthe pile. Reinforcement similar to that used in the pile shall be securelyfastened to the projecting steel and the necessary form work shall be placed,care being taken to prevent leakage along the pile. The concrete shall be

of the same quality as that used in the pile. Just prior to placing concrete the top of the pile shall be thoroughly wetted and covered with athin coating of neat cement, retempered mortar or other suitable bondingmaterial. The forms shall remain in place not less than seven days andshall then be carefully removed and the entire exposed surface of the pilefinished as above specified.

2. 3. 17.—Painting Steel Piles and Steel Pile Shells.

Unless otherwise provided, when steel piles or steel pile shells extendabove the ground surface or water surface they shall be protected by threecoats of paint as specified for Painting of Metal Structures. This protection shall extend from an elevation 2 feet below the water or groundsurface to the top of the exposed steel.


(a) General.

Piling, whether timber, concrete or steel, will be paid for accordingto Methods A or B as designated in the contract.

(b) Method A.For furnishing and driving piles at the contract price per linear foot.

(1) Cutoff. —The total cutoff of piling shall be paid for at the prices setforth by the Commission, in the special provisions for those of the followingitems incorporated in the work:

Cutoff, untreated timber piles, per linear foot $Cutoff, treated timber piles, per linear foot $Cutoff, precast concrete piles, per linear foot $Cutoff, steel shells for piles (.12" or more in thickness), per linear foot. . $Cutoff, steel piles, per pound $

(2) Furnishing and Driving. —The number of linear feet to be paid forshall be the actual length of piles remaining in the completed structureand the number of linear feet of cutoff to be paid for shall be the actualnumber of linear feet cut off, except that no allowance will be made forlengths in excess of those ordered by the engineer, and except that if thecontractor casts concrete piles full length of the reinforcing bars to facilitate driving, no payment will be made for that portion where concrete mustbe removed in order that bars may project as shown on the plans.If paid for as "cutoff," cutoff material (if the cutoff is in excess of 3 feetin length) shall become the property of the Commission. Cutoff material3 feet or less in length, and other cutoff material which, in the opinion ofthe engineer, is not worth salvaging shall be disposed of to the satisfactionof the engineer.

36 HIGHWAY BRIDGES

(3) Payment for Furnishing and Driving Piles.—Payment for furnishing and driving piles shall include the material and work specified under"Payment for Furnishing Piles" and "Payment for Driving Piles" —MethodB.

(c) Method B.

For furnishing piles at the contract price per linear foot. For drivingpiles at the contract price per linear foot.

(1) Furnishing. —The number of linear feet of timber, precast concreteor steel piles to be paid for shall be the total ordered length of piles whichare driven and which have been furnished in accordance with the lengthsdesignated by the engineer, except that if the contractor casts concretepiles full length of the reinforcing bars to facilitate driving, no paymentwill be made for that portion where concrete must be removed in orderthat bars may project as shown on the plans. Cutoff material 3 feet or lessin length and other cutoff material which, in the opinion of the engineer, isnot worth salvaging, shall be disposed of to the satisfaction of the engineer.

The number of linear feet of cast-in-place piles to be paid for shall bethe actual number of linear feet of piles remaining in the completedstructure. The length measured shall include both the steel shell and thereinforced concrete extension as measured from the point of the tip of thepile to the bottom of the cap or bottom of the footing, as the case may be.

(2) Driving. —The number of linear feet to be paid for shall be thetotal number of linear feet of piling remaining in the completed structure.For driving cast-in-place piles the length measured shall include both thesteel shell and the reinforced concrete extensions as measured from thepoint of the tip of the pile to the bottom of the cap or bottom of the footing,as the case may be.

(3) Payment for Furnishing Piles.—Payment for furnishing pilesshall include full compensation for furnishing the piling or all material required therefor ready for placement, including all material necessary for extensions and build-ups and for completion of the pile, and for all labor, tools,hauling, equipment, handling, treatment and all work incidental to the construction of the piling prior to driving or construction of build-ups and extensions. Payment shall also include (a) reinforcing in concrete pilesrequired to extend beyond the end of the pile for connections; (b) the fittingand attaching of steel shoes when they are specified for timber piles; (c) thefurnishing and attachment of brackets, lugs, core stoppers and cap plateson steel piling.

(4) Payment for Driving Piles.—Payment for driving piles per linearfoot shall include full compensation for furnishing all labor, tools, materials,supplies, equipment and other necessary or incidental costs of handling,driving, cutting off piles, treatment of pile heads, constructing build-upsand extensions of concrete piles, painting of steel piles and all other incidental work connected therewith. It shall also include full compensationfor all jetting, drilling, blasting, or other work necessary to obtain the required penetration or bearing values of piles.

(d) Falsework and Defective Piles.No payment will be made for the furnishing or driving of falsework

piles, nor will payment be made for piles driven out of place, for defectivepiles, or for piles which are damaged in handling or driving.

(e) Additional Requirements.

If the length of wood piles, steel piles or steel pile shells designated

CONSTRUCTION 37

by the engineer is not sufficient, the splicing, including labor, equipmentand material, shall be paid for on the basis of extra work unless a contractitem is provided to cover the payment.

Brackets, plates or other reinforcement on steel piles required by theengineer in addition to those shown on the plans will be paid for as extrawork.

If not covered by a contract item, metal shoes for piling, ordered bythe engineer, will be paid for at cost delivered to the site, plus 15 per cent.

No additional allowance, or adjustment, will be made in the contractprices for furnishing or driving piling because of these additionalrequirements.

2. 3. 19 Payment for Test Piles.

Test piles ordered by the engineer shall be paid for as follows :

If piles are used in the structure as a result of the tests, the test pilesshall be paid for as in the case of other piles.

If, however, piling is not used in the structure, the test piles will bepaid for as provided for extra work, due consideration being given to thecost of bringing the pile driver to the site and removing it from the work.

2. 3. 20.—Payment for Loading Tests.

Payment for loading tests shall include the cost of all material, equipment and labor incidental to making the loading test or tests as directedby the engineer, or as specified in the special provisions. Payment shall bemade on the basis of the contract price for pile loading tests, or, in theabsence of such a price, shall be made on the basis of extra work

SECTION 4—Concrete Masonry2. 4. 1.—General.

Concrete masonry shall consist of portland cement, aggregates andwater which shall conform to the requirements of division IV and whichshall be proportioned as hereinafter specified.

2. 4. 2.—Care and Storage of Concrete Aggregates.

The handling and storage of concrete aggregates shall be such as toprevent segregation or the admixture of foreign materials; the engineermay require that aggregates be stored on separate platforms at satisfactorylocations.

When specified in the special provisions, the coarse aggregate shall be

separated into two or more sizes in order to secure greater uniformity ofthe concrete mixture. Different sizes of aggregate shall be stored inseparate stock piles sufficiently removed from each other to prevent thematerial at the edges of the piles from becoming intermixed.

2. 4. 3.—Storage of Cement.

All cement shall be stored in suitable weatherproof buildings whichwill protect the cement from dampness. These buildings shall be placedin locations approved by the engineer. Provision for storage shall be ample,and the shipments of cement as received shall be separately stored in sucha manner as to provide easy access for the identification and inspection ofeach shipment. Storage buildings shall have a capacity for the storage ofa sufficient quantity of cement to allow sampling at least 12 days before

88 HIGHWAY BRIDGES

the cement is to be used. Stored cement shall meet the test requirementsat any time after storage when a retest is ordered by the engineer.

On small jobs, storage in the open may be permitted by written authorization from the engineer, in which case a raised platform and amplewaterproof covering shall be provided.

When required by the terms of the contract, the contractor shall keepaccurate records of the deliveries of cement and of its use in the work.Copies of these records shall be supplied to the engineer in such form as

may be required.

2. 4. 4.—Classes of Concrete.

The classes of concrete are A, B, C, X and Y. Each class of concreteshall be used in that part of the structure in which it is called for on theplans, or where directed by the engineer. Unless otherwise specified,Class A concrete shall be used. The following requirements shall governunless otherwise shown on the plans:

Class A concrete shall be used for all superstructures, except as notedbelow, and for reinforced substructures except where the sections aremassive and lightly reinforced. The more important items of work includedare slabs, beams, girders, columns, arch ribs, box culverts, reinforced abutments and retaining walls and reinforced footings. Class A concrete shallbe used for precast piles and cribbing. Class A concrete shall also be usedfor work exposed to salt water.

Concrete deposited in water shall be Class A with 10 per cent additionalcement. Class B concrete shall be used for mass footings, pedestals,massive pier shafts and gravity walls, with none or only a small amountof reinforcing.

Class C concrete shall be used for very massive unreinforced sections.Class X coB.tfrete shall be used for massive sections, lightly reinforced

where a higher grade than Class B is desired.Class Y concrete shall be used in thin reinforced sections, for handrails

except as specified for precast railing under "Railings," and for filler insteel grid floors.

2. 4. 5.—L-Classification and Proportioning of Concrete Mixtures.

Concrete shall be proportioned to secure the strength and durabilityrequired for the part of the structure in which it is to be used.

The following classes and uses of concrete are recognized in thesespecifications :

Minimum compressive strength

at 28 days

DesignatedClass size of coarse

aggregate Use

lbs. per so. in.3,000

square openings

A 1 in. to No. 4 General use and concrete exposed to sea water.

B 2,200 2 in. to No. 4 Massive sections or lightly reinforced sections.

C 1,5003,000

2% in. to No. 42 in. to No. 4

Massive unreinforced sections.X Massive sections or lightly rein

forced sections.3,000 V2 in. to No. 4 Thin reinforced sections or hand

rails.

The concrete of the various classes given in the above table shall be

designed so as to secure concrete having not less than the strengths specified

CONSTRUCTION 39

and shall be proportioned by one of the methods, A or B, given below.Unless otherwise specified in the supplemental specifications or specialprovisions, Method B shall be used.

Proportions Based on Strength

(a) Method A.

The proportions of cement, aggregates and water necessary to conformto these specifications shall be determined by means of preliminary laboratory tests on concrete made with the cement and aggregates which are tobe used in the work.

For each class of concrete, the proportions by weight of cement, fineand coarse aggregate and the quantity of water will be designated by theengineer so as to meet the requirements given in the following table :

Designated Minimum Maximum net Consistency,size of coarse compressive water content range in slump

Class of concrete aggregate strength at per bag of28 days cement regular vi

square openings placing brated

lbs. per sq. in. gallona inchesA 1 in. to No. 4 3,000 6.0 3-5 2-41! 2 in. to No. 4 2,200 7.0 2-3 1-2C 2'/j in. to No. 4 1,500 8.5 2-3 1-2X 2 in. to No. 4 3,000 6.0 2-3 1-2

% in. to No. 4 3,000 6.0 3-5 2-4

The engineer will furnish prospective bidders, in the special provisions,the proportions by weight and the theoretical cement content per cubic yardwhich will be required for each combination of materials from regularcommercial sources of which previously determined test data are available.

Immediately upon receipt of the award of the contract, the contractorshall furnish the engineer with the exact location of the sources of thematerials which he proposes to use. If the source of materials proposedby the contractor is different than set forth in the special provisions, adesign of the mix will be made and the proportions officially designated bythe engineer. The designated proportions shall be used so long as thematerials are actually furnished from the sources originally named andso long as they continue to meet the requirements herein specified, subjectonly to slight changes in the relative quantities of fine and coarse aggregate for the purpose of promoting workability.

If, during the progress of the work, the contractor wishes to usematerials for which no proportions have been designated, the engineerreserves the right to change the proportions in order to meet the requirements specified in the table above using the materials actually furnished.

If, during the progress of the work, it is found impossible to obtainconcrete of the required workability, with the designated proportions, theengineer may make such changes in proportions as are deemed necessaryto secure the desired workability, provided that in no case shall the ratioof water to cement be greater than is specified in the table above for theclass of concrete involved, and provided further that any increase ordecrease in the amount of cement which may be required as the result ofsuch changes shall be adjusted for or against the contractor, as the casemay be, in accordance with the following rule:

If such alterations change the theoretical cement factor originally setforth in the special provisions by 2 per cent or less, no adjustment in. the

40 HIGHWAY BRIDGES

amount paid the contractor will be made. If such alterations change thetheoretical cement factor by more than 2 per cent, the source and qualityof the aggregates remain the same, payment will be adjusted for or againstthe contractor in whatever amount the total cost of cement, f. o. b. contractor's material yard, has been increased or decreased by more than 2 percent. The amount of such increase or decrease shall be calculated from thetheoretical cement factor determined by the laboratory for the materialused and not by count of bags of cement used or of the batches where bulkcement is used. No adjustment will be made if the source of materials isdifferent than provided for in the special provisions.

Proportions Based on a Constant Cement Factor

(b) Method B.

The weights of fine and coarse aggregate per bag (94 pounds) ofcement, the maximum size of coarse aggregate and the consistency for eachclass of concrete shall be as follows:

Amount of saturatedsurface dry aggregateper bag (94 pounds)

of cement

Maximumnet watercontentper bag

of cement

Consistency range inslump

Classof

Designatedsize of coarse

aggregate

Minimumcementfactorconcrete

Fine Coarse

RegularPlacing Vibrated

squareopenings

Bags per Founds Pounds Gallons IncheB Inchescu. 3rd.

Gravel Coarse Aggregate

A 1 in to No. 4 6.S 175 300 6.0 8-5 2-4B 2 in. to No. 4 5.0 250 408 7.0 2-3 1-2C 2% in. to No. 4 4.0 325 524 8.5 2-3 1-2X 2 in. to No. 4 6.0 199 384 6.0 2-8 1-2Y % in. to No. 4 7.0 177 250 6.0 3-5 2-4

Stone Coarse Aggregate

A 1 in to No. 4 6.5 199 276 6.0 8-5 2-4B 2 in. to No. 4 5.0 283 375 7.0 2-8 1-2C 2% in. to No. 4 4.0 868 481 8.5 2-8 1-2X 2 in. to No. 4 6.0 225 308 6.0 2-8 1-2r % in. to No. 4 7.0 199 228 6.0 8-5 2-4

Slag Coarse Aggregate

A 1 in to No. 4 6.5 207 227 6.0 8-5 2-4B 2 in. to No. 4 5.0 294 809 7.0 2-8 1-2C 2% in. to No. 4 4.0 382 396 8.5 2-8 1-2X 2 in. to No. 4 6.0 235 253 6.0 2-8 1-2Y % in. to No. 4 7.0 205 188 6.0 8-5 2-4

Note. Using the maximum allowable water content, the weights given above when multiplied by the corresponding cement factors will furnish a cubic yard of concrete (absolutevolume ) .

The consistency range and the ratios of fine aggregate to total aggregate computed fromthe weights shown above are based on the methods of placing which do not involve high frequency vibration. Where vibration is employed the ratios of fine aggregate to total aggregatemay be reduced about 5 per cent.

The minimum cement factor specified is for usual climatic conditions and quality ofconcrete materials. Where climatic conditions are favorable, and where concrete materialsavailable produce exceptionally high strength concrete, the engineer may lower the specifiedcement factor, but not to exceed 10 per cent, with suitable adjustment in water content.When a reduction is made, it shall be stipulated in the special provisions.

CONSTRUCTION 41

The proportions by weight given in the table above are based on themaintenance of an approximately constant quantity of cement per cubicyard of concrete. The proportions are based on the use of aggregateshaving bulk specific gravities in a saturated surface-dry condition of 2.65

plus or minus 0.05 for sand, gravel and crushed stone, and 2.25 plus orminus 0.05 for crushed slag. For other specific gravities, the weights shallbe corrected by multiplying the weights shown in the table by the ratio ofthe specific gravities of the aggregates used and those used in computingthe table. The bulk specific gravity tests shall be made in accordance withMethods of Sampling and Testing A. A. S. H. O. Method T-84-45, section 6,

and Method T-85-45, section 6 (A. S. T. M. Designation C-128-42 andC-127-42, respectively).

Since the weights given in the table are computed for aggregates ina saturated surface-dry condition, the batch weights shall be corrected toaccord with the moisture condition of the aggregates delivered to themeasuring bin. Absorption tests shall be made in accordance with Methodsof Sampling and Testing A. A. S. H. O. Method T-84-45, section 8, andMethod T-85-45, section 8 (A. S. T. M. Designation C-128-42 and C-127-42,respectively).

The weights of sand and coarse aggregate given in the table have been

calculated on the basis of using a well-eraded natural sand in combinationwith a well-graded coarse aggregate. These weights are subject to change,depending upon the gradation of the materials furnished by the contractor.

The weights of fine and coarse aggregate will be adjusted by theengineer to insure concrete of satisfactory plasticity and workability, usingnot more than the maximum permissible net water content shown. Duringthe progress of the work, the total weight of aggregate per bag of cementshall not be changed except under the following conditions:

(1) If concrete of satisfactory plasticity and workability cannot be

made without exceeding the maximum net water content, the engineer shallreduce the total weight of aggregate by an amount sufficient to insure thatthe maximum net water content will not be exceeded, and the contractorshall not receive additional compensation for any extra cement which maybe necessary by reason of such adjustment.

(2) If during the progress of the work the specific gravity of one orboth of the aggregates changes, the batch weights shall be changedaccordingly.

(3) The compression tests used in determining the strength of concreteshall conform to Method T-23-45, "Method of Making and Storing Compression Specimens of Concrete in the Field," and Method T-22-45, "Methodof Making Compression Tests of Concrete," "Methods of Sampling andTesting," of the A. A. S. H. 0. (A. S. T. M. Designations C-31-44 andC-39-44, respectively) .

2. 4. 6.—Consistency.

Concrete shall have a consistency such that it will be workable in therequired position. It shall be of such a consistency that it will flow aroundreinforcing steel but individual particles of the coarse aggregate whenisolated shall show a coating of mortar containing its proportionate amountof sand. The consistency of concrete shall be gauged by the ability of theequipment to properly place it and not by the difficulty in mixing or transporting. The quantity of mixing water shall be determined by the engineerin accordance with article 2. 4. 5. and shall not be varied without his consent.

In general the slump, for concrete placed by the usual methods, when

42 HIGHWAY BRIDGES

made in accordance with the Standard Method of Slump Test for Consistencyof Portland Cement Concrete, A. A. S. H. O., Method T-119-42 (A. S. T. M.Designation C-143-39), shall be as follows:

For mass concrete, not over 2 inches.For lightly reinforced concrete sections, easily accessible for spading

and working, not over 3 inches.For reinforced concrete sections, not easily accessible for spading and

working due to amount or spacing of steel, or other reasons, not over4 inches.

For sections which are inaccessible to a workman, such as long slendercolumns, etc., not over 5 inches.

In the case of structural steel encasement, where the deposited concretemust pass through very small openings, the above provisions shall notgovern.

Batches in the same section shall be uniform.When the vibration method of placing concrete is used the slump shall

generally be from one-half to two-thirds of that given above. Concrete as

dry as it is practical to place with the equipment specified shall be used.

2. 4. 7.—Measurement of Materials.

Materials shall be measured by weighing, except as otherwise specifiedor where other methods are specifically authorized by the engineer. Theapparatus provided for weighing the aggregates and cement shall be

suitably designed and constructed for this purpose. Each size of aggregateand the cement shall be weighed separately. The accuracy of all weighingdevices shall be such that successive quantities can be measured to within1 per cent of the desired amount. Cement in standard packages (sack)need not be weighed, but bulk cement shall be weighed. The mixing watershall be measured by volume or by weight. The water measuring deviceshall be susceptible of control accurate to plus or minus % per cent ofthe capacity of the tank. All measuring devices shall be subject to approval.

Where volumetric measurements are authorized by the engineer forprojects where the amount of concrete is small, the weight proportionsshall be converted to equivalent volumetric proportions. In such cases,suitable allowance shall be made for variations in the moisture conditionof the aggregates, including the bulking effect in the fine aggregate.

When the aggregates contain more water than the quantity necessaryto produce a saturated surface-dry condition as contemplated in article2. 4. 5, representative samples shall be taken and the moisture contentdetermined for each kind of aggregate.

When sack cement is used the quantities of aggregates for each batchshall be exactly sufficient for one or more full sacks of cement and no batchrequiring fractional sacks of cement will be permitted.

2. 4. 8.—Mixing Concrete.

(a) General.

Unless otherwise authorized by the engineer, concrete shall be machinemixed at the site.

(b) Mixing at Site.

Concrete shall be thoroughly mixed in a batch mixer of an approvedsize and type which will insure a uniform distribution of the materialsthroughout the mass.

The mixer shall be equipped with adequate water storage and a devicefor accurately measuring and automatically controlling the amount of

CONSTRUCTION

Jwater used in each batch. Preferably, mechanical means shall be providedfor recording the number of revolutions for each batch and automaticallypreventing the discharge of the mixer until the materials have been mixedthe specified minimum time.

The entire contents of the mixer shall be removed from the drum beforematerials for a succeeding batch are placed therein. The materials composing a batch shall be deposited simultaneously in the mixer. No mixerhaving a rated capacity of less than a 1-bag batch shall be used nor shalla mixer be charged in excess of its rated capacity.

All concrete shall be mixed for a period of not less than 1% minutesafter all materials, including water, are in the mixer. During the periodof mixing, the mixer shall operate at the speed for which it has beendesigned, but this speed shall be not less than 14 nor more than 20 revolutions per minute.

The first batch of concrete materials placed in the mixer shall containa sufficient excess of cement, sand and water to coat the inside of the drumwithout reducing the required mortar content of the mix. Upon the cessation of mixing for a considerable period, the mixer shall be thoroughlycleaned.

(c) Truck Mixing.

Truck mixers, unless otherwise authorized by the engineer, shall be ofthe revolving drum type, watertight, and so constructed that the concretecan be mixed to insure a uniform distribution of materials throughout themass. All solid materials for the concrete shall be accurately measured inaccordance with article 2. 4. 7. and charged into the drum at the proportioning plant. Except as subsequently provided, the truck mixer shall be

equipped with a tank for carrying mixing water. Only the prescribedamount of water shall be placed in the tank unless the tank is equippedwith a device by which the quantity of water added can be readily verified.The mixing water may be added directly to the batch, in which case a tankshall not be required. Truck mixers may be required to be provided withmeans by which the mixing time can be readily verified by the engineer.

The maximum size of batch in truck mixers shall not exceed themaximum rated capacity of the mixer as stated by the manufacturer andstamped in metal on the mixer. Truck mixing shall be continued for notless than 50 revolutions after all ingredients, including the water, are inthe drum. The speed shall not be less than 4 r. p. m., nor more than aspeed resulting in a peripheral velocity of the drum of 225 feet per minute.Not more than 100 revolutions of mixing shall be at a speed in excess of6 r. p. m. Mixing shall begin within 30 minutes after the cement has beenadded either to the water or aggregate.

When cement is charged into a mixer drum containing water or surface-wet aggregate and when the temperature is above 90° F., or when high-early strength portland cement is used, this limit shall be reduced to 15

minutes; the limitation on time between the introduction of the cement tothe aggregates and the beginning of the mixing may be waived when, inthe judgment of the engineer, the aggregates are sufficiently free frommoisture, so that there will be no harmful effects on the cement.

(d) Partial Mixing at the Central Plant.When a truck mixer, or an agitator provided with adequate mixing

blades, is used for transportation, the mixing time at the stationary machinemixer may be reduced to 30 seconds and the mixing completed in a truck

44 HIGHWAY BRIDGES

mixer or agitator. The mixing time in the truck mixer or agitator equippedwith adequate mixing blades shall be as specified for truck mixing.

(e) Plant Mix.Mixing at a central plant shall conform to the requirements for mixing

at the site.

(f) Time of Hauling and Placing Mixed Concrete.Concrete transported in a truck mixer, agitator, or other transporta

tion device shall be discharged at the job and placed in its final position inthe forms within 1% hours after the introduction of the mixing water tothe cement and aggregate, or the cement to the aggregate, except that inhot weather or under other conditions contributing to quick stiffening ofthe concrete, the maximum allowable time may be reduced by the engineer.The maximum volume of mixed concrete transported in an agitator shallbe in accordance with the specified rating.

(g) Hand Mixing.When hand mixing is authorized it shall be done on a watertight

platform and in such a manner as to insure a uniform distribution of thematerials throughout the mass. Mixing shall be continued until a homogeneous mixture of the required consistency is obtained.

(h) Delivery.

The organization supplying concrete shall have sufficient plant capacityand transporting apparatus to insure continuous delivery at the raterequired. The rate of delivery of concrete during concreting operationsshall be such as to provide for the proper handling, placing and finishingof the concrete. The rate shall be such that the interval between batchesshall not exceed 20 minutes. The methods of delivering and handling theconcrete shall be such as will facilitate placing with the minimum ofrehandling and without damage to the structure or the concrete.

(i) Retempering.The concrete shall be mixed only in such quantities as are required for

immediate use and any which has developed initial set shall not be used.Concrete which has partially hardened shall not be retempered or remixed.

2. 4. 9.—Handling and Placing Concrete,

(a) General.

In preparation for the placing of concrete all sawdust, chips, and otherconstruction debris and extraneous matter shall be removed from the interior of forms. Struts, stays and braces, serving temporarily to hold theforms in correct shape and alignment, pending the placing of concrete attheir locations, shall be removed when the concrete placing has reached anelevation rendering their service unnecessary. These temporary membersshall be entirely removed from the forms and not buried in the concrete.

No concrete shall be used which does not reach its final position inthe forms within the time stipulated under "Time of Hauling and PlacingMixed Concrete," article 2. 4. 8.

Concrete shall be placed so as to avoid segregation of the materials andthe displacement of the reinforcement. The use of long troughs, chutes andpipes for conveying concrete from the mixer to the forms shall be permittedonly on written authorization of the engineer. In case an inferior qualityof concrete is produced by the use of such conveyors, the engineer may

CONSTRUCTION 45

order discontinuance of their use and the substitution of a satisfactorymethod of placing.

Open troughs and chutes shall be of metal or metal lined; where steepslopes are required, the chutes shall be equipped with baffles or be in shortlengths that reverse the direction of movement.

All chutes, troughs and pipes shall be kept clean and free from coatingsof hardened concrete by thoroughly flushing with water after each run;water used for flushing shall be discharged clear of the structure.

When placing operations would involve dropping the concrete morethan 5 feet, it shall be deposited through sheet metal or other approvedpipes. As far as practicable, the pipes shall be kept full of concrete duringplacing and their lower ends shall be kept buried in the newly placed concrete. After initial set of the concrete the forms shall not be jarred andno strain shall be placed on the ends of reinforcing bars which project.

Concrete, during and immediately after depositing, shall be thoroughlycompacted. The compaction shall be done by mechanical vibration subjectto the following provisions:

(1) The vibration shall be internal unless special authorization of othermethods is given by the engineer or as provided herein.

(2) Vibrators shall be of a type and design approved by the engineer.They shall be capable of transmitting vibration to the concrete at frequencies of not less than 4500 impulses per minute.

(3) The intensity of vibration shall be such as to visibly affect a massof concrete of 1-inch slump over a radius of at least 18 inches.

(4) The contractor shall provide a sufficient number of vibrators toproperly compact each batch immediately after it is placed in the forms.

(5) Vibrators shall be manipulated so as to thoroughly work the concrete around the reinforcement and imbedded fixtures and into the cornersand angles of the forms.

Vibration shall be applied at the point of deposit and in the area offreshly deposited concrete. The vibrators shall be inserted and withdrawnout of the concrete slowly. The vibration shall be of sufficient duration andintensity to thoroughly compact the concrete, but shall not be continued so

as to cause segregation. Vibration shall not be continued at any one pointto the extent that localized areas of grout are formed.

Application of vibrators shall be at points uniformly spaced and notfarther apart than twice the radius over which the vibration is visiblyeffective.

(6) Vibration shall not be applied directly or through the reinforcement to sections or layers of concrete which have hardened to the degreethat the concrete ceases to be plastic under vibration. It shall not be usedto make concrete flow in the forms over distances so great as to causesegregation, and vibrators shall not be used to transport concrete in theforms.

(7) Vibration shall be supplemented by such spading as is necessaryto insure smooth surfaces and dense concrete, along form surfaces and incorners and locations impossible to reach with the vibrators.

(8) The provisions of this article shall apply to the filler concrete forsteel grid floor except that the vibrator shall be applied to the steel.

(9) The provisions of this article shall apply to precast piling, concretecribbing and other precast members except that, if approved by the engineer,

the manufacturers' methods of vibrations may be used.

Concrete shall be placed in horizontal layers not more than 12 inches

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thick except as hereinafter provided. When less than a complete layer isplaced in one operation, it shall be terminated in a vertical bulkhead. Eachlayer shall be placed and compacted before the preceding batch has takeninitial set to prevent injury to the green concrete and avoid surfaces ofseparation between the batches. Each layer shall be compacted so as toavoid the formation of a construction joint with a preceding layer whichhas not taken initial set.

When the placing of concrete is temporarily discontinued, the concrete,after becoming firm enough to retain its form, shall be cleaned of laitanceand other objectionable material to a sufficient depth to expose sound concrete. To avoid visible joints as far as possible upon exposed faces, thetop surface of the concrete adjacent to the forms shall be smoothed with a

trowel. Where a "feather edge" might be produced at a construction joint,as in the sloped top surface of a wing wall, an inset form work shall beused to produce a blocked out portion in the preceding layer which shallproduce an edge thickness of not less than 6 inches in the succeedinglayer. Work shall not be discontinued within 18 inches of the top of anyface, unless provision has been made for a coping less than 18 inches thick,in which case, if permitted by the engineer, the construction joint may be

made at the under side of the coping.Immediately following the discontinuance of placing concrete all accum

ulations of mortar splashed upon the reinforcing steel and the surfaces offorms shall be removed. Dried mortar chips and dust shall not be puddledinto the unset concrete. If the accumulations are not removed prior to theconcrete becoming set care shall be exercised not to injure or break theconcrete-steel-bond at and near the surface of the concrete, while cleaningthe reinforcing steel

(b) Culverts.In general, the base slab or footings of box culverts shall be placed and

allowed to set before the remainder of the culvert is constructed. In thiscase suitable provision shall be made for bonding the sidewalls to the culvertbase, preferably by means of raised longitudinal keys so constructed as toprevent, as far as possible, the percolation of water through the construction joint.

Before concrete is placed in the sidewalls, the culvert footings shall be

thoroughly cleaned of all shavings, sticks, sawdust, or other extraneousmaterial and the surface carefully chipped and roughened in accordancewith the method of bonding construction joints as specified herein.

In the construction of box culverts 4 feet or less in height, the sidewallsand top slab may be constructed as a monolith. When this method of construction is used, any necessary construction joints shall be vertical andat right angles to the axis of the culvert.

In the construction of box culverts more than 4 feet in height, theconcrete in the walls shall be placed and allowed to set before the top slabis placed. In this case, appropriate keys shall be left in the sidewalls foranchoring the cover slab.

Each wing wall shall be constructed, if possible, as a monolith. Construction joints, where unavoidable, shall be horizontal and so located thatno joint will be visible in the exposed face of the wing wall above theground line.

(c) Girders, Slabs and Columns.Concrete, preferably, shall be deposited by beginning at the center of

the span and working from the center toward the ends. Concrete in girders

CONSTRUCTION 47

shall be deposited uniformly for the full length of the girder and broughtup evenly in horizontal layers.

Concrete in girder haunches less than 3 feet in height shall be placedat the same time as that in the girder stem, and the column or abutmenttops shall be cut back to form seats for the haunches. Whenever anyhaunch or fillet has a vertical height of 3 feet or more, the abutment orcolumns, the haunch and the girder shall be placed in three successivestages; first, up to the lower side of the haunch; second, to the lower sideof the girder; and third, to completion.

Concrete in slab spans shall be placed in one continuous operation foreach span unless otherwise provided.

The floors and girders of through girder superstructures shall be placedin one continuous operation unless otherwise specified, in which case specialshear anchorage shall be provided to insure monolithic action betweengirder and floor.

Concrete in T-beam or deck girder spans may be placed in one continuous operation or may be placed in two separate operations, each ofwhich shall be continuous; first, to the top of the girder stems, and second,to completion. In the latter case, the bond between stem and slab shall be

positive and mechanical, and shall be secured by means of suitable shearkeys in the top of the girder stem. The size and location of these keysshall be computed. In general, suitable keys may be formed by the use oftimber blocks approximately 2 by 4 inches in cross-section and having alength 4 inches less than the width of the girder stem. These key blocksshall be spaced along the girder stems as required, but the spacing shallbe not greater than 1 foot center to center. The blocks shall be beveled andoiled in such manner as to insure their ready removal, and they shall be

removed as soon as the concrete has set sufficiently to retain its shape.Concrete in columns shall be placed in one continuous operation, unless

otherwise directed. The concrete shall be allowed to set at least 12 hoursbefore the caps are placed.

Unless otherwise permitted by the engineer, no concrete shall be placedin the superstructure until the column forms have been stripped sufficientlyto determine the character of the concrete in the columns. The load of thesuperstructure shall not be allowed to come upon the bents until they havebeen in place at least 14 days, unless otherwise permitted by the engineer.

(d) Arches.

The concrete in arch rings shall be placed in such a manner as to loadthe centering uniformly.

Arch rings, preferably, shall be cast in transverse sections of such sizethat each section can be cast in a continuous operation. The arrangementof the sections and the sequence of placing shall be as approved by theengineer and shall be such as to avoid the creation of initial stress in thereinforcement. The sections shall be bonded together by suitable keys ordowels. When permitted by the engineer, arch rings may be cast in a singlecontinuous operation.

2. 4. 10.—Pneumatic Placing.

Pneumatic placing of concrete will be permitted only if specified in thespecial provisions or if authorized by the engineer. The equipment shallbe so arranged that no vibrations result which might damage freshly placedconcrete.

Where concrete is conveyed and placed by pneumatic means the equip

48 HIGHWAY BRIDGES

ment shall be suitable in kind and adequate in capacity for the work.The machine shall be located as close as practicable to the place of deposit.The position of the discharge end of the line shall not be more than 10 feetfrom the point of deposit. The discharge lines shall be horizontal or inclinedupwards from the machine.

At the conclusion of placement the entire equipment shall be thoroughlycleaned.

2. 4. 11.—Pumping.

Placement of concrete by pumping will be permitted only if specifiedin the special provisions or if authorized by the engineer. The equipmentshall be so arranged that no vibrations result which might damage freshlyplaced concrete.

Where concrete is conveyed and placed by mechanically applied pressurethe equipment shall be suitable in kind and adequate in capacity for thework. The operation of the pump shall be such that a continuous streamof concrete without air pockets is produced. When pumping is completed,the concrete remaining in the pipeline, if it is to be used, shall be ejectedin such a manner that there will be no contamination of the concrete orseparation of the ingredients. After this operation, the entire equipmentshall be thoroughly cleaned.

2. 4. 12.—Depositing Concrete Under Water.

Concrete shall not be deposited in water except with the approval ofthe engineer and under his immediate supervision; and in this case themethod of placing shall be as hereinafter designated.

Concrete deposited in water shall be Class A with 10 per cent excesscement. To prevent segregation, it shall be carefully placed in a compactmass, in its final position, by means of a tremie, a bottom dump bucket orother approved method, and shall not be disturbed after being deposited.Still water shall be maintained at the point of deposit and the forms underwater shall be water-tight.

For parts of structures under water, when possible, concrete seals shallbe placed continuously from start to finish; the surface of the concreteshall be kept as nearly horizontal as practicable at all times. To insurethorough bonding, each succeeding layer of a seal shall be placed beforethe preceding layer has taken initial set.

A tremie shall consist of a tube having a diameter of not less than 10

inches, constructed in sections having flanged couplings fitted with gaskets.The tremies shall be supported so as to permit free movement of the discharge end over the entire top surface of the work and so as to permitrapid lowering when necessary to retard or stop the flow of concrete. Thedischarge end shall be closed at the start of work so as to prevent waterentering the tube and shall be entirely sealed at all times; the tremie tubeshall be kept full to the bottom of the hopper. When a batch is dumpedinto the hopper, the flow of concrete shall be induced by slightly raisingthe discharge end, always keeping it in the deposited concrete. The flowshall be continuous until the work is completed.

Depositing of concrete by the drop bottom bucket method shall conformto the following specification. The top of the bucket shall be open. Thebottom doors shall open freely downward and outward when tripped. Thebucket shall be completely filled and slowly lowered to avoid backwash.It shall not be dumped until it rests on the surface upon which the concreteis to be deposited and when discharged shall be withdrawn slowly until well

CONSTRUCTION 49

above the concrete. The slump of concrete shall be maintained between4 and 8 inches.

Unwatering may proceed when the concrete seal is sufficiently hard andstrong. All laitance or other unsatisfactory material shall be removed fromthe exposed surface by scraping, chipping or other means which will notinjure the surface of the concrete.

2. 4. 13.—Construction Joints.

(a) General.

Construction joints shall be made only where located on the plans orshown in the pouring schedule, unless otherwise approved by the engineer.

If not detailed on the plans, or in the case of emergency, constructionjoints shall be placed as directed by the engineer. Shear keys or inclinedreinforcement shall be used where necessary to transmit shear or bond thetwo sections together.

(b) Bonding.Before depositing new concrete on or against concrete which has

hardened, the forms shall be retightened. The surface of the hardenedconcrete shall be roughened as required by the engineer, in a manner thatwill not leave loosened particles of aggregate or damaged concrete at thesurface. It shall be thoroughly cleaned of foreign matter and laitance, andsaturated with water. To insure an excess of mortar at the juncture of thehardened and the newly deposited concrete, the cleaned and saturatedsurfaces, including vertical and inclined surfaces, shall first be thoroughlycovered with a coating of mortar or neat cement grout against which thenew concrete shall be placed before the grout has attained its initial set.

The placing of concrete shall be carried continuously from joint tojoint. The face edges of all joints which are exposed to view shall be

carefully finished true to line and elevation.

2. 4. 14.—Rubble or Cyclopean Concrete.

Rubble or cyclopean concrete shall consist of either Class B or C concrete, as specified, containing large embedded stones. It shall be usedonly with the approval of the engineer in massive piers, gravity abutments,and heavy footings. The stone for this class of work may be one-man stoneor derrick stone conforming to the requirements of division IV.

The stone shall be carefully placed —not dropped or cast—so as to avoidinjury to the forms or to the partially set adjacent masonry. Stratifiedstone shall be placed upon its natural bed. All stone shall be washed andsaturated with water before placing.

The total volume of the stone shall not be greater than one-third of thetotal volume of the portion of the work in which it is placed. For walls orpiers greater than 2 feet in thickness, one-man stone may be used; eachstone shall be surrounded by at least 6 inches of concrete; and no stoneshall be closer than 1 foot to any top surface nor any closer than 6 inchesto any coping. For walls or piers greater than 4 feet in thickness, derrickstone may be used; each stone shall be surrounded by at least 1 foot ofconcrete; and no stone shall be closer than 2 feet to any top surface norcloser than 8 inches to any coping.

2. 4. 1S.—Concrete Exposed to Sea Water.

Unless otherwise specifically provided, concrete for structures exposedto sea water shall be Class A concrete as specified in article 2. 4. 5. Theclear distance from the face of the concrete to the nearest face of reinforce

50 HIGHWAY BRIDGES

ment steel shall be not less than 4 inches. The concrete shall be mixed fora period of not less than 2 minutes and the water content of the mixtureshall be carefully controlled and regulated so as to produce concrete ofmaximum impermeability. The concrete shall be thoroughly compacted andstone pockets shall be avoided. No construction joints shall be formedbetween levels of extreme low water and extreme high water as determinedby the engineer. Between these levels sea water shall not come in directcontact with the concrete for a period of not less than 30 days. The originalsurface, as the concrete comes from the forms, shall be left undisturbed.

2. 4. 16.—Concrete Exposed to Alkali Soils or Alkali Water.

Where concrete may be exposed to the action of alkaline waters or soils,special care shall be taken to place it in accordance with placing specifications herein. Wherever possible placing shall be continuous until completion of the section or until the concrete is at least 18 inches above groundor water level. Alkaline waters or soils shall be kept from contact with theconcrete during placement and for a period of at least 72 hours thereafter.

2. 4. 17.—Falsework and Centering.

Unless otherwise provided, detailed plans for falsework or centeringshall be supplied to the engineer on request, but, in no case shall the contractor be relieved of responsibility for results obtained by the use of theseplans.

For designing falsework and centering, a weight of 150 pounds percubic foot shall be assumed for green concrete. All falsework shall be

designed and constructed to provide the necessary rigidity and to supportthe loads without appreciable settlement or deformation. The engineer mayrequire the contractor to employ screw jacks or hardwood wedges to takeup any settlement in the formwork either before or during the placingof concrete.

Falsework which cannot be founded on a satisfactory footing shall be

supported on piling which shall be spaced, driven and removed in a mannerapproved by the engineer.

Falsework shall be set to give the finished structure the camber specified or indicated on the plans.

Arch centering shall be constructed according to centering plansapproved by the engineer. Provision shall be made by means of suitablewedges, sand boxes or other device for the gradual lowering of centers, andrendering the arch self-supporting. When directed, centering shall be

placed upon approved jacks in order to take up and correct any slightsettlement which may occur after the placing of masonry has begun.

2. 4. 18.—Forms.

All forms shall be of wood or metal and shall be built mortartight andof sufficient rigidity to prevent distortion due to the pressure of the concreteand other loads incident to the construction operations. Forms shall beconstructed and maintained so as to prevent warping and the opening ofjoints due to shrinkage of the lumber.

The forms shall be substantial and unyielding and shall be so designedthat the finished concrete will conform to the proper dimensions and contours. The design of the forms shall take into account the effect ofvibration of concrete as it is placed.

Forms for exposed surfaces shall be made of dressed lumber of uniformthickness with or without a form liner of an approved type, and mortar

CONSTRUCTION 51

tight. Forms shall be filleted at all sharp corners and shall be given a

bevel or draft in the case of all projections, such as girders and copings,to insure easy removal.

Metal ties or anchorages within the forms shall be so constructed as

to permit their removal to a depth of at least 2 inches from the face withoutinjury to the concrete. In case ordinary wire ties are permitted, all wires,upon removal of the forms, shall be cut back at least V* inch from theface of the concrete with chisels or nippers; for green concrete, nippersare necessary. All fittings for metal ties shall be of such design that, upontheir removal, the cavities which are left will be of the smallest possiblesize. The cavities shall be filled with cement mortar and the surface leftsound, smooth, even and uniform in color.

All forms shall be set and maintained true to the line designated untilthe concrete is sufficiently hardened. Forms shall remain in place forperiods which shall be determined as hereinafter specified. When formsappear to be unsatisfactory in any way, either before or during' the placingof concrete, the engineer shall order the work stopped until the defectshave been corrected.

The shape, strength, rigidity, watertightness and surface smoothnessof re-used forms shall be maintained at all times. Any warped or bulgedlumber must be re-sized before being re-used. Forms which are unsatisfactory in any respect shall not be re-used.

For narrow walls and columns, where the bottom of the form is inaccessible, the lower form boards shall be left loose so that they may be

removed for cleaning out extraneous material immediately before placingthe concrete.

All forms shall be treated with oil or saturated with water immediatelybefore placing the concrete. For rail members or other members withexposed faces, the forms shall be treated with an approved oil to preventthe adherence of concrete. Any material which will adhere to or discolorthe concrete shall not be used.

2. 4. 19.—Removal of Falsework, Forms and Housing.

In the determination of the time for the removal of falsework, formsand housing, and the discontinuance of heating, consideration shall be givento the location and character of the structure, the weather and other conditions influencing the setting of the concrete, and the materials used inthe mix.

If field operations are not. controlled by beam or cylinder tests, thefollowing periods, exclusive of days when the temperature is below 40",for removal of forms and supports may be used as a guide :

Arch centers 14 daysCentering under beams 14 daysFloor slabs 7-14 daysWalls 12-24 hrs.Columns 1-7 daysSides of beams and all other parts 12-24 hrs.

If high-early strength cement is used these periods may be reduced a&

directed by the engineer.If field operations are controlled by beam or cylinder tests, the removal

of forms, supports and housing, and the discontinuance of heating andcuring may be begun when the strengths reach values which shall be fixedby the engineer for the particular method of testing which is to be used.The beams or cylinders shall be cured under conditions which are not more

52 HIGHWAY BRIDGES

favorable than the most unfavorable conditions for the portions of theconcrete which the beams represent.

Methods of form removal likely to cause overstressing of the concreteshall not be used. In general, the forms shall be removed from the bottomupwards. Forms and their supports shall not be removed without theapproval of the engineer. Supports shall be removed in such a manner asto permit the concrete to uniformly and gradually take the stresses dueto its own weight.

In general, arch centering shall be struck and the arch made self-supporting before the railing or coping is placed. This precaution isessential in order to avoid jamming of the expansion joints and variationsin alignment. For filled spandrel arches, such portions of the spandrelwalls shall be left for construction subsequent to the striking of centers,as may be necessary to avoid jamming of the expansion joints.

Centers shall be gradually and uniformly lowered in such a manneras to avoid injurious stresses in any part of the structure. In arch structures of two or more spans, the sequence of striking centers shall bespecified or approved by the engineer.

2. 4. 20.—Concreting in Cold Weather.

No concrete shall be placed when the atmospheric temperature is below35° F. without written permission of the engineer. When directed by theengineer, the contractor shall enclose the structure in such a way that theconcrete and air within the enclosure can be kept above 60° F. for a periodof seven days after placing the concrete.

If high early strength cement is used these periods may be reduced,as directed by the engineer.

The contractor shall supply such heating apparatus as stoves, salamanders or steam equipment and the necessary fuel. When dry heat isused, means of maintaining atmospheric moisture shall be provided. Allaggregates and mixing water shall be heated to a temperature of at least70° but not more than 150° F.; the aggregates may be heated by eithersteam or dry heat. If permitted by the engineer the torch method ofheating mixed concrete may be used, provided the heating apparatus shallbe such as to heat the mass uniformly and avoid hot spots which will burnthe materials. The temperature of the concrete shall be not less than 60°at the time of placing in the forms. In case of extremely low temperatures, the engineer may, at his discretion, raise the minimum limitingtemperatures for water, aggregates and mixed concrete.

2. 4. 21.—Curing Concrete.Concrete surfaces exposed to conditions causing premature drying

shall be protected by covering as soon as possible with canvas, straw,burlap, sand or other satisfactory material and kept moist; or if the surfaces are not covered, they shall be kept moist by flushing or sprinkling.Curing shall continue for a period of not less than seven days after placingthe concrete. If high-early strength cement is used this period may bereduced, as directed by the engineer. Other precautions to insure thedevelopment of strength shall be taken as the engineer may direct.

2. 4. 22.—Expansion and Fixed Joints and Bearings.

All joints shall be constructed according to details shown on the plans.

(a) Open Joints.Open joints shall be placed in the locations shown on the plans and

shall be constructed by the insertion and subsequent removal of a wood

CONSTRUCTION 53

strip, metal plate or other approved material. The insertion and removalof the template shall be accomplished without chipping or breaking thecorners of the concrete. Reinforcement shall not extend across an openjoint unless so specified on the plans.

(b) Filled Joints.Poured expansion joints shall be constructed similar to open joints.

When premolded types are specified, the filler shall be placed in correctposition as the concrete on one side of the joint is placed. When the formis removed, the concrete on the other side shall be placed. Metal waterstops shall be carefully placed as shown on the plans.

Cc) Steel Joints.The plates, angles or other structural shapes shall be accurately shaped,

at the shop, to conform to the section of the concrete floor. The fabrication and painting shall conform to the requirements of these specificationscovering those items. When called for on the plans or in the special provisions the material shall be galvanized in lieu of painting. Care shall be

taken to insure that the surface in the finished plane is true and free ofwarping. Positive methods shall be employed in placing the joints to keepthem in correct position during the placing of the concrete. The openingat expansion joints shall be that designated on the plans at normal temperature, and care shall be taken to avoid impairment of the clearance in anymanner.

(d) Water Stops.

Metal water stops shall be furnished and placed as provided on theplans. They shall be spliced, welded, or soldered, to form continuous watertight joints.

(e) Bearing Devices.

Bearing plates, rockers and other expansion devices shall be constructedaccording to details shown on the plans. Unless set in plastic concrete oras otherwise specified, they shall be set in grout to insure uniform bearing.Bronze or copper-alloy plates shall conform to the requirements of article4. 12. 1. or 4. 12. 2. Structural steel and painting shall conform to thespecifications for those items. When called for on the plans or in thespecial provisions, the material shall be galvanized in lieu of painting.The rockers or other expansion devices shall be set to conform to thetemperature at the time of erection.

Finishing Concrete Surfaces2. 4. 23.—General.

Surface finishes shall be classified as follows:Class 1. Ordinary surface finish.Class 2. Rubbed finish.Class 3. Tooled finish.Class 4. Sand-blast finish.Class 5. Wire brush, or scrubbed finish.Class 6. Floated surface finish.

All concrete shall be given Class 1, Ordinary Surface Finish, and inaddition, if further finishing is required, such other type of finish as isspecified. If not otherwise specified, the following surfaces shall be givena Class 2, Rubbed Finish: The exposed faces of piers, abutments, wingwalls and retaining walls; the outside faces of girders, T-beams, slabs,columns, brackets, curbs, headwalls, railings, arch rings, spandrel walls

54 HIGHWAY BRIDGES

and parapets; but not on the tops and bottoms of floor slabs and sidewalks,bottoms of beams and girders, sides of interior beams and girders, back-walls above bridge seat or the underside of copings. The surface finish onpiers and abutments shall include all exposed surfaces below bridge seatto 1 foot below low water elevation or 2 feet below finished ground linewhen such ground line is above the water surface. Wing walls shall befinished from the top to 2 feet below the finish slope lines on the outsideface and shall be finished on top and for a depth of 1 foot below the topon the back sides.

Unless otherwise specified, roadway floors shall be given Class 6,Floated Surface Finish.

2. 4. 24.—Class 1, Ordinary Surface Finish.Immediately following the removal of forms, all fins and irregular

projections shall be removed from all surfaces except from those which arenot to be exposed or are not to be waterproofed. On all surfaces, the cavities produced by form ties and all other holes, honeycomb spots, brokencorners or edges and other defects shall be thoroughly cleaned, and afterhaving been kept saturated with water for a period of not less than threehours shall be carefully pointed and trued with a mortar of cement andfine aggregate mixed in the proportions used in the grade of the concretebeing finished. Mortar used in pointing shall be not more than one hourold. The mortar patches shall be cured as specified under Curing. Allconstruction and expansion joints in the completed work shall be leftcarefully tooled and free of all mortar and concrete. The joint filler shallbe left exposed for its full length with clean and true edges.

The resulting surfaces shall be true and uniform. All surfaces whichcannot be repaired to the satisfaction of the engineer shall be "rubbed" asspecified for Class 2, Rubbed Finish.

2. 4. 25.—Class 2, Rubbed Finish.After removal of forms the rubbing of concrete shall be started as soon

as its condition will permit. Immediately before starting this work theconcrete shall be kept thoroughly saturated with water for a minimumperiod of three hours. Sufficient time shall have elapsed before the wettingdown to allow the mortar used in the pointing of rod holes and defects tothoroughly set. Surfaces to be finished shall be rubbed with a mediumcoarse carborundum stone, using a small amount of mortar on its face.The mortar shall be composed of cement and fine sand mixed in proportionsused in the concrete being finished. Rubbing shall be continued until allform marks, projections and irregularities have been removed, all voidsfilled and a uniform surface has been obtained. The paste produced bythis rubbing shall be left in place at this time.

After all concrete above the surface being treated has been cast, thefinal finish shall be obtained by rubbing with a fine carborundum stone andwater. This rubbing shall be continued until the entire surface is of a

smooth texture and uniform color.After the final rubbing is completed and the surface has dried, it shall

be rubbed with burlap to remove loose powder and shall be left free fromall unsound patches, paste, powder and objectionable marks.

2. 4. 26.—Class 3, Tooled Finish.Finish of this character for panels and other like work may be secured

by the use of a bushhammer, pick, crandall, or other approved tool. Airtools, preferably, shall be employed. No tooling shall be done until the

CONSTRUCTION 55

concrete has set for at least 14 days and as much longer as may benecessary to prevent the aggregate particles from being "picked" out of thesurface. The finished surface shall show a grouping of broken aggregateparticles in a matrix of mortar, each aggregate particle being in slightrelief.

2. 4. 27 Class 4, Sand Blasted Finish.The thoroughly cured concrete surface shall be sand blasted with hard,

sharp sand to produce an even fine-grained surface in which the mortarhas been cut away, leaving the aggregate exposed.

2. 4. 28.—Class 5, Wire Brushed or Scrubbed Finish.This type of finish shall be produced by scrubbing the surface of a

green concrete with stiff wire or fiber brushes, using a solution of muriaticacid in the proportion of 1 part acid to 4 parts water. As soon as theforms are removed and while the concrete is yet comparatively green, thesurface shall be thoroughly and evenly scrubbed as above described untilthe cement film or surface is completely removed and the aggregate particlesare exposed, leaving an even pebbled texture presenting an appearancegrading from that of fine granite to coarse conglomerate, depending uponthe size and grading of aggregate used. As soon as the scrubbing hasprogressed sufficiently to produce the texture desired, the entire surfaceshall be thoroughly washed with water to which a small amount of ammoniahas been added to remove all traces of the acid.

2. 4. 29.—Class 6, Floated Surface Finish.(a) Striking Off.

After the concrete is compacted as specified under article 2.4.9(a),the surface shall be carefully rodded and struck off with a strike boardto conform to the cross section and grade shown on the plans. Properallowance shall be made for camber, if required. The strike board may be

operated longitudinally or transversely and shall be moved forward witha combined longitudinal and transverse motion, the manipulation beingsuch that neither end is raised from the side forms during the process.A slight excess of concrete shall be kept in front of the cutting edge atall times.

(b) Floating.After striking off and consolidating as specified above, the surface

shall be made uniform by longitudinal or transverse floating, or both.Longitudinal floating will be required except in places where this methodis not feasible.

(c) Longitudinal Floating.The longitudinal float, operated from foot bridges, shall be worked

with a sawing motion while held in a floating position parallel to the roadcenterline and passing gradually from one side of the pavement to the

other. The float shall then be moved forward one-half of its length andthe above operation repeated. Machine floating which produces equivalent

results may be substituted for the above hand method.

(d) Transverse Floating.The transverse float shall be operated across the pavement by starting

at the edge and slowly moving to the center and back again to the edge.

The float shall then be moved forward one-half of its length and the aboveoperations repeated. Care shall be taken to preserve the crown and crosssection of the pavement.

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(e) Straightedging.

After the longitudinal floating has been completed and the excess waterremoved, but while the concrete is still plastic, the slab surface shall betested for trueness with a straightedge. For this purpose the contractorshall furnish and use an accurate 10-foot straightedge swung from handles3 feet longer than one-half the width of the slab.

The straightedge shall be held in successive positions parallel to theroad centerline and contact with the surface and the whole area gone overfrom one side of the slab to the other as necessary. Advance along thedeck shall be in successive stages of not more than one-half the length ofthe straightedge. Any depressions found shall be immediately filled withfreshly mixed concrete, struck off, consolidated and refinished. High areasshall be cut down and refinished. The straightedge testing and refloatingshall continue until the entire surface is found to be free from observabledepartures from the straightedge and the slab has the required grade andcontour, until there are no deviations of more than % inch under the 10-footstraightedge.

(f) Final Finishing.

When the concrete has hardened sufficiently, the surface shall be givena broom finish. The broom shall be of an approved type. The strokes shallbe square across the slab, from edge to edge, with adjacent strokes slightlyoverlapped, and shall be made by drawing the broom without tearing theconcrete, but so as to produce regular corrugations not over % of an inch indepth. The surface as thus finished shall be free from porous spots, irregularities, depressions and small pockets or rough spots such as may be

caused by accidental disturbing, during the final brooming, of particles ofcoarse aggregate embedded near the surface.

2. 4. 30.—Sidewalk Finish.

After the concrete has been deposited in place, it shall be compactedand the surface shall be struck off by means of a strike board and floatedwith a wooden or cork float. An edging tool shall be used on all edges andat all expansion joints. The surface shall not vary more than % inch

(0.125") under a 10-foot straightedge. The surface shall have a granularor matte texture which will not be slick when wet.

Sidewalk surfaces shall be laid out in blocks with an approved groovingtool as shown on the plans or as directed by the engineer.

2. 4. 31.—Pneumatically Applied Mortar.

(a) General.

This section refers to premixed sand and cement pneumatically appliedby suitable mechanism and competent operators, and to which mixture thewater is added immediately previous to its expulsion from the nozzle.

(b) Proportions.

The proportion of cement to sand shall be based on dry and loosevolumes and shall not be less than one to four for encasement of steelmembers, one to three for concrete repair, nor one to four and a half forspecial linings.

(c) Water Content.

The water content shall be maintained at a practicable minimum andnot in excess of 3 gallons per sack of cement as placed.

CONSTRUCTION 57

(d) Mixing.The cement and sand shall be thoroughly mixed before being charged

into the machine. The sand shall contain not less than 3 nor more than 6

per cent moisture by weight.

(e) Nozzle Velocity.

The velocity of the material as it leaves the nozzle must be maintaineduniform at a rate determined for the given job conditions to produceminimum rebound.

Cf) Nozzle Position.The nozzle shall be held in such a position and at such distance that

the stream of flowing material will impinge at approximately right anglesto the surface being covered without excessive impact.

(g) Rebound Sand.

Rebound or accumulated loose sand shall be removed from the surfaceto be covered prior to placing of the original or succeeding layers of mortar.

(h) Forms.

The forms shall be structurally sufficient and of such design thatrebound or accumulated loose sand can freely escape or be readily removed.Shooting strips should be used at corners, edges, and on surfaces wherenecessary to obtain true lines and proper thickness.

(i) Joints.

The pneumatically applied mortar at the end of any day's work orsimilar stopping periods shall be sloped off to a thin edge. Before placingan adjacent section this sloped portion shall be thoroughly cleaned andwetted.

(j) Bond.

Surfaces to which pneumatically applied mortar is to be bonded shallbe thoroughly cleaned of dirt, paint, grease, organic matter and looseparticles. Absorptive surfaces shall be wetted before the application ofthe mortar.

(k) Curing.

Pneumatically applied mortar shall be so applied, protected, and curedas to prevent its temperature falling below 50° F., or a loss of moisturefrom the surface for the periods indicated below:

(1) Where normal portland cement is used, 7 days.

(2) Where high-early strength portland cement is used, 3 days.

Pneumatically applied mortar shall be applied only with the permissionof the engineer if the air temperature is 50° P. or less.

(I) Reinforcement.

The reinforcement when required shall be adequate from the standpoint of structural requirements and shall consist of mesh or round bars,spaced not less than 2 inches nor more than 4 inches apart either way,and having a diameter not less than that of No. 12 wire. The area of thereinforcement shall be at least 0.2 per cent of the cross-sectional area ofthe mortar. The reinforcement shall be at least % inch from the unexposed surface of the mortar and at least % inch from the exposed surface.

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The payment for concrete of the various classes shall include compensation for all equipment, tools, material, falsework, forms, bracing, labor,surface finish and all other items of expense required to complete the concrete work shown on the plans, with the exception of reinforcing steel. Thepayment for concrete shall include the cost of joint fillers, metal drains,expansion joints and miscellaneous metal devices unless they are coveredby other items in the contract. The quantity of concrete involved in fillets,scorings and chamfers 1 square inch or less in cross-sectional area shallbe neglected. Payment will be made on the basis of the actual yardagewithin the neat lines of the structure as shown on the plans or revised byauthority of the engineer, except that deduction shall be rnade as follows:

(1) The volume of structural steel, including steel piling, encased inconcrete.

(2) The volume of timber piles encased in concrete, assuming thevolume to be .8 cubic foot per linear foot of pile.

(3) The volume of concrete piles encased in concrete.

No deduction shall be made for the volume of concrete displaced bysteel reinforcement, floor drains, or expansion joint material. If a bid isasked on handrailing, that portion of the railing above the top of the roadway curb or above the surface of the sidewalk, as the case may be, shallnot be included in the yardage of concrete, but shall be paid for as hand-railing. Massive pylons or posts which are to be excepted from handrailpayment shall be so noted on the plans.

Payment for pneumatically applied mortar will be made on the basisof the actual number of square feet placed and accepted. The payment forpneumatically applied mortar shall include compensation for all equipment,tools, materials, labor and incidentals necessary to complete the work andshall include metal reinforcement unless otherwise provided.

SECTION 5— Reinforcement

2. 5. 1.—Material.

All material shall conform to the requirements of division IV. Theuse of only one grade of steel will be allowed on any one contract, unlessotherwise noted on the plans or in the special provisions.

2. 5. 2. —Order Lists.

Before ordering material, all order lists and bending diagrams shall be

furnished by the contractor for the approval of the engineer, and no ma

terials shall be ordered until such lists and bending diagrams have been

approved. The approval of order lists and bending diagrams by the engineer shall in no way relieve the contractor of responsibility for the correctness of such lists and diagrams. Any expense incident to the revision ofmaterial furnished in accordance with such lists and diagrams to make itcomply with the design drawings shall be borne by the contractor.

2. 5. 3.—Protection of Material.

Steel reinforcement shall be protected at all times from injury. Whenplaced in the work, it shall be free from dirt, detrimental scale, paint, oilor other foreign substance. However, when steel has, on its surface, detri

CONSTRUCTION 69

mental rust, loose scale and dust which is easily removable, it may becleaned by a satisfactory method, if approved by the engineer.

2. 5. 4.—Fabrication.

Bent bar reinforcement shall be cold bent to the shapes shown on theplans, and unless otherwise provided on the plans or by authorization,bends shall be made in accordance with the following requirements :

Stirrups and tie bars shall be bent around a pin having a diameter notless than two times the minimum thickness of the bar. Bends for otherbars shall be made around a pin having a diameter not less than six timesthe minimum thickness except for bars larger than 1 inch, in which casethe bends shall be made around a pin of eight bar diameters.

Bar reinforcement shall be shipped in standard bundles, tagged andmarked in accordance with the Code of Standard Practice of the ConcreteReinforcement Steel Institute.

2. 5. 5.—Mesh Reinforcement.Mesh reinforcement shall conform to the requirements of division IV,

and shall be fabricated as shown on the plans.

2. 5. 6.—Bar Mat Reinforcement.Bar mat reinforcement shall conform to the requirements of division IV.

2. 5. 7.—Placing and Fattening.

All steel reinforcement shall be accurately placed in the positions shownon the plans and firmly held during the placing and setting of concrete.When placed in the work it shall be free from dirt, detrimental rust, loosescale, paint, oil or other foreign material. Bars shall be tied at all intersections except where spacing is less than 1 foot in each direction whenalternate intersections shall be tied.

Distances from the forms shall be maintained by means of stays, blocks,ties, hangers, or other approved supports. Blocks for holding reinforcement from contact with the forms shall be precast mortar blocks of approvedshape and dimensions or approved metal chairs. Metal chairs which are incontact with the exterior surface of the concrete shall be galvanized. Layersof bars shall be separated by precast mortar blocks or by other equallysuitable devices. The use of pebbles, pieces of broken stone or brick, metalpipe and wooden blocks shall not be permitted. The minimum spacing ofbars shall be as specified in article 3. 7. 7. Reinforcement in any membershall be placed and then inspected and approved by the enginer before theplacing of concrete begins. Concrete placed in violation of this provisionmay be rejected and removal required.

If fabric reinforcement is shipped in rolls, it shall be straightened intoflat sheets before being placed.

2. 5. 8.—Splicing.

All reinforcement shall be furnished in the full lengths indicated onthe plans. Splicing of bars, except where shown on the plans, will not be

permitted without the written approval of the engineer. Splices shall bestaggered as far as possible.

Unless otherwise shown on the plans, bars shall be lapped 40 diametersto make the splice. In lapped splices, the bars shall be placed in contactand wired together in such a manner as to maintain a clearance of not

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less than the minimum clear distance to other bars and the minimumdistance to the surface of the concrete specified in article 3. 7. 7. Weldingof reinforcing steel shall be done only if detailed on the plans or if authorizedby the engineer in writing. Welding shall conform to the current specifications for Welded Highway and Railway Bridges of the American Welding Society.

2. S. 9.—Lapping.

Sheets of mesh or bar mat reinforcement shall overlap each othersufficiently to maintain a uniform strength and shall be securely fastenedat the ends and edges. The edge lap shall not be less than one mesh inwidth.

2. 5. 10.—Substitutions.

Substitution of different size bars will be permitted only with specificauthorization by the engineer. If steel is substituted, it shall have an areaequivalent to the design area, or larger.

2. 5. 11.—Measurement.

Steel reinforcement incorporated in the concrete masonry will be

measured in pounds based on the total computed weight for the sizes andlengths of bars, mesh or mats as shown on the plans or authorized.

The weight of mesh will be computed from the theoretical weight ofplain wire. If the weight per square foot is given on the plan, that weightshall be used.

The weight of plain or deformed bars or bar mat will be computed fromthe theoretical weight of plain round or square bars of the same nominalsize as shown in the following table :

Size M" Vs" W Vs" 3A" Vs" 1" W V4' WWeight

in Round . . 0.167 0.376 0.668 1.043 1.502 2/44 2.670pounds

per Square . . 0.850 3.400 4.303 5.313 7.650foot

The weight of reinforcement used in railings, when they are paid for on

a linear foot basis, shall not be included. The weight of reinforcement inprecast piles and other items where the reinforcement is included in thecontract price for the item shall not be included.

No allowance will be made for clips, wire, separators, wire chairs, andother material used in fastening the reinforcing in place. If bars are substituted upon the contractor's request and as a result more steel is usedthan specified, only the amount specified shall be included.

When laps are made for splices, other than those shown on the plans,for the convenience of the contractor, the extra steel shall not be included.

2. S. 12.—Payment.

Payment for reinforcement as determined under measurement shall be

made at the contract price per pound. Payment shall include the cost offurnishing, fabricating and placing of the reinforcement.

CONSTRUCTION 61

SECTION 6—Ashlar Masonry

2. 6. 1.—Description.

Ashlar masonry shall consist of first-class cut stone masonry laid inregular courses and shall include all work in which, as distinguished fromrubble masonry, the individual stones are dressed or tooled to exactdimensions.


Materials shall conform to the requirements of division IV, supplemented as follows:

Stone.

The stone shall be kept free from dirt, oil or any other injurious material which may prevent the proper adhesion of the mortar or detractfrom the appearance of the exposed surfaces.

Mortar.Mortar for laying the stone and pointing shall be composed of one part

of portland cement and three parts of sand unless otherwise provided. Thesand shall conform to the requirements of division IV for "Sand forMortar."

2. 6. 3.—Size of Stone.

The individual stones shall be large and well proportioned. They shallnot be less than 12 nor more than 30 inches in thickness. The thicknessesof courses, if varied, shall diminish regularly from bottom to top of wall.The size of ring stones in arches shall be as shown on the plans.

2. 6. 4.—Surface Finishes of Stone.

For the purpose of this specification the surface finishes of stone aredefined as follows:

Smooth-finished: Having a surface in which the variations from thepitch line do not exceed Me inch.

Pine-finished: Having a surface in which the variations from the pitchline do not exceed % inch.

Rough-finished: Having a surface in which the variations from thepitch line do not exceed % inch.

Scabbled: Having a surface in which the variations from the pitchline do not exceed 94 inch.

Rock-faced: Having an irregular projecting face without indicationsof tool marks. The projections beyond the pitch line shall not exceed 3

inches and no part of the face shall recede back of the pitch line.

2. 6. 5.—Dressing Stone.

Stones shall be dressed to exact sizes and shapes before being laid andshall be cut to lie on their natural beds with top and bottom truly parallel.Hollow beds will not be permitted. The bottom bed shall be the full sizeof the stone and no stone shall have an overhanging top. In rock-faceconstruction the face side of any stone shall not present an undercut contouradjacent to its bottom arris giving a top-heavy, unstable appearance whenlaid.

Beds of face stone shall be fine-finished for a depth of not less than12 inches.

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Vertical joints of face stone shall be fine-finished and full to the squarefor a depth of not less than 9 inches.

Exposed surfaces of the face stone shall be given the surface finishindicated on the plans, with edges pitched to true lines and exact batter.Chisel drafts 1% inches wide shall be cut at all exterior corners. Facestone forming the starling or nosing of piers shall be rough-finished unlessotherwise specified.

Holes for stone hooks shall not be permitted to show in exposed surfaces.

2. 6. 6.—Stretchers.

Stretchers shall have a width of bed of not less than 1% times theirthickness. They shall have a length of not less than twice their thickness,nor less than 3 feet, and not more than 3% times their thickness.

2. 6. 7.—Headers.

Headers shall be placed in each course and shall have a width of notless than 1% times their thickness. In walls having a thickness of 4 feetor less, the headers shall extend entirely through the wall. In walls ofgreater thickness, the length of headers shall be not less than 2% timestheir thickness when the course is 18 inches or less in height, and not lessthan 4 feet in courses of greater height. Headers shall bond with thecore or backing not less than 12 inches. Headers shall hold in the heart ofthe wall the same size shown in the face and shall be spaced not furtherapart than 8 feet center to center. There shall be at least one header toevery two stretchers.

2. 6. 8.—Cores and Backing.

Cores and backing shall consist either of roughly bedded and jointedheaders and stretchers, as specified above, or of Class "B" or "C" concrete,as may be specified.

When stone is used for cores or backing, at least % of the stone shallbe of the same size and character as the face stone and with parallel ends.No course shall be less than 8 inches thick.

Concrete used for cores and backing shall conform to the requirementsspecified for Concrete Masonry, division II.

The headers and stretchers in walls having a thickness of 3 feet orless shall have a width or length equal to the full thickness of the wall.No backing will be allowed.

2. 6. 9.—Mixing Mortar.

The mortar shall be hand or machine mixed, as may be required bythe engineer. In the preparation of hand-mixed mortar, the sand andcement shall be thoroughly mixed together in a clean, tight mortar boxuntil the mixture is of uniform color, after which clean water shall be

added in such quantity as to form a stiff plastic mass. Machine-mixedmortar shall be prepared in an approved mixer and shall be mixed 'not lessthan 1% minutes. Mortar shall be used within 45 minutes after mixing.Retempering of mortar will not be permitted.

2. 6. 10.—Laying Stone,

(a) General.

Stone masonry shall not be constructed in freezing weather or whenthe stone contains frost, except by written permission of the engineer andsubject to such conditions as he may require.

CONSTRUCTION 63

(b) Face Stone.

Stone shall not be dropped upon or slid over the wall, nor will hammering, rolling or turning of stones on the wall be allowed, but shall be carefully set without jarring the stone already laid and they shall be handledwith a lewis or other appliance which will not cause disfigurement.

Each stone shall be cleaned and thoroughly saturated with water beforebeing set and the bed which is to receive it shall be cleaned and wellmoistened. All stones shall be well bedded in freshly made mortar andsettled in place with a suitable wooden maul before the setting of the mortar.Whenever possible, the face joints shall be properly pointed before themortar sets. Joints which cannot be so pointed shall be prepared for pointing by raking them out to a depth of 2 inches before the mortar has set.The face surfaces of stones shall not be smeared with the mortar forced outof the joints or that used in pointing. No pinning up of stones with spallswill be permitted and no spalls will be permitted in beds.

Joints and beds shall be not less than % inch nor more than % inchin thickness and the thickness of the joint or bed shall be uniformthroughout.

The stones in any one course shall be placed so as to form bonds of notless than 12 inches with the stones of adjoining courses. Headers shall be

placed over stretchers and, in general, the headers of each course shallequally divide the spaces between the headers of adjoining courses, but noheader shall be placed over a joint and no joint shall be made over a header.

(c) Stone Backing and Cores.

Stone backing shall be laid in the same manner as specified above forface stone, with headers interlocking with face headers when the thicknessof the wall will permit. Backing shall be laid to break joints with the facestone. Stone cores shall be laid in full mortar beds so as to bond not lessthan 12 inches with face and backing stone and with each other. Bedjoints in cores and backing shall not exceed 1 inch and vertical joints shallnot exceed 4 inches in thickness.

(d) Concrete Cores and Backing.

The operations involved in the handling and placing of concrete usedin cores and backing shall conform to the requirements specified for "Concrete Masonry." However, the puddling and compacting of concrete adjacent to the ashlar masonry facing shall be done in a manner that willinsure the filling of all spaces around the stones and secure full contact

and efficient bond with all stone surfaces.

2. 6. 11.—Leveling Courses.

Stone cores and backing shall be carried up to the approximate level

of the face course before the succeeding course is started.

The construction joints produced in concrete cores or backing by the

intermittent placing of concrete shall be located, in general, not less than

6 inches below the top bed of any course of masonry.

2. 6. 12.—Resetting.

In case any stone is moved or the joint broken, the stone shall be

taken up, the mortar thoroughly cleaned from bed and joints, and the stonereset in fresh mortar.

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2. 6. 13.—Dowels and Cramps.

Where required, coping stone, stone in the wings of abutments and

stone in piers shall be secured with wrought-iron cramps or dowels asindicated on the plana.

Dowel holes shall be drilled through each stone before the stone isplaced and, after it is in place, such dowel holes shall be extended bydrilling into the underlying course not less than 6 inches.

Cramps shall be of the shapes and dimensions shown on the plans orapproved by the engineer. They shall be inset in the stone so as to be flushwith the surfaces.

Cramps and dowels shall be set in lead, care being taken to completelyfill the surrounding spaces with the moulten metal.

2. 6. 14.—Copings.

Stones for copings of walls, piers and abutment bridge seats shallbe carefully selected and fully dimensioned stones. On piers, not morethan two stones shall be used to make up the entire width of coping andthe copings of abutment bridge seats shall be of sufficient width to extendat least 4 inches under the backwall. Each step forming the coping of awing wall shall be formed by a single stone which shall overlap the stoneforming the step immediately below it at least 12 inches.

Tops of copings shall be given a bevel cut at least 2 inches wide, andbeds, bevel cuts and tops shall be fine-finished. The vertical joints shallbe smooth-finished and the copings shall be laid with joints not more than% inch in thickness. The under sides of projecting copings, preferably,shall have a drip bead.

Joints in copings shall be located so as to provide not less than a12-inch bond with the stones of the under course and so that no joint willcome directly under the superstructure masonry plates.

2. 6. I5.—Arches.

The number of courses and the depth of voussoirs shall be as shown onthe plans. Voussoirs shall be placed in the order indicated, shall be fullsize throughout, dressed true to template, and shall have bond not less thanthe thickness of the stone. Beds and joints shall be fine-finished and mortarjoints shall not exceed % inch in thickness. Exposed surfaces of the in-trados and arch ring shall be given the surface finish indicated on the plans.

Backing may consist of Class B concrete or of large stones shaped tofit the arch, bonded to the spandrels, and laid in full beds of mortar. Theextrados and interior faces of the spandrel walls shall be given a finishingcoat of 1:2% cement mortar which shall be trowelled smooth to receive thewaterproofing.

Arch centering, waterproofing, drainage and filling shall be as specifiedfor concrete arches.

2. 6. 16.—Pointing.

Pointing shall not be done in freezing weather nor when the stonecontains frost.

Joints not pointed at the time the stone is laid shall be thoroughly wetwith clean water and filled with mortar. The mortar shall be well driveninto the joints and finished with an approved pointing tool. The wall shallbe kept wet while pointing is being done and in hot or dry weather thepointed masonry shall be protected from the sun and kept wet for a periodof at least three days after completion.

CONSTRUCTION 65

After the pointing is completed and the mortar set, the wall shall bethoroughly cleaned and left in a neat and workmanlike condition.


The quantity of stone masonry to be paid for under this item shallbe the number of cubic yards measured in the completed work and thelimiting dimensions shall not exceed those shown upon the plans or fixedby the engineer. The contract price shall include all labor, tools, materialsand other expense incidental to the satisfactory completion of the work.

SECTION 7—Mortar Rubble Masonry2. 7. 1.—Description.

Mortar rubble masonry, as here specified, shall include the classes commonly known as coursed, random and random range work and shall consistof roughly squared and dressed stone laid in cement mortar.


Materials shall conform to the requirements of division IV supplemented as follows:Stone.

The stone shall be kept free from dirt, oil, or any other injuriousmaterial which may prevent the proper adhesion of the mortar.

Mortar.The mortar used shall conform as regards materials, proportions and

mixing to the mortar specified for "Ashlar Masonry."

2. 7. 3.—Size.

Individual stones shall have a thickness of not less than 8 inches anda width of not less than 1 % times the thickness. No stones, except headers,shall have a length less than 1% times their width. Stone shall decreasein thickness from bottom to top of wall.

The size of ring stones for arches shall be as shown on the plans.

2. 7. 4.—Headers.

Headers shall hold in the heart of the wall the same size shown in theface and shall extend not less than 12 inches into the core or backing. Theyshall occupy not less than % of the face area of the wall and shall be evenlydistributed. Headers in walls 2 feet or less in thickness shall extendentirely through the wall.

2. 7. 5.—Shaping Stone.The stones shall be roughly squared on joints, beds and faces. Selected

stone, roughly squared and pitched to line, shall be used at all angles andends of walls. If specified, all corners or angles in exterior surfaces shallbe finished with a chisel draft.

All shaping or dressing of stone shall be done before the stone is laidin the wall, and no dressing or hammering which will loosen the stone willbe permitted after it is placed.

2. 7. 6.—Laying Stone.

Stone masonry shall not be constructed in freezing weather or when thestone contains frost, except by written permission of the engineer andsubject to such conditions as he may require.

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The masonry shall be laid to line and in courses roughly leveled up.The bottom or foundation courses shall be composed of large, selected stonesand all courses shall be laid with bearing beds parallel to the natural bed

of the material.Each stone shall be cleaned and thoroughly saturated with water before

being set and the bed which is to receive it shall be cleaned and wellmoistened. All stones shall be well bedded in freshly made mortar. Themortar joints shall be full and the stones carefully settled in place beforethe mortar has set. No spalls will be permitted in the beds. Joints andbeds shall have an average thickness of not more than 1 inch.

Whenever possible the face joints shall be properly pointed before themortar becomes set. Joints which cannot be so pointed shall be preparedfor pointing by raking them out to a depth of 2 inches before the mortarhas set. The face surfaces of stones shall not be smeared with the mortarforced out of the joints or that used in pointing.

The vertical joints in each course shall break joints with those inadjoining courses at least 6 inches. In no case shall a vertical joint be so

located as to occur directly above or below a header.

In case any stone is moved or the joint broken, the stone shall be takenup, the mortar thoroughly cleaned from bed and joints, and the stone resetin fresh mortar.

2. 7. 7.—Copings, Bridge Seats and Backwalls.

Copings, bridge seats and backwalls shall be of the materials shown onthe plans and when not otherwise specified shall be of Class "A" concretewhich shall conform to the requirements for "Concrete Masonry."

Concrete copings shall be made in sections extending the full width ofthe wall, not less than 12 inches in thickness, and from 5 to 10 feet long.The sections may be cast in place or precast and set in place in fullmortar beds.

2. 7. 8 Arches.

The number of courses and the depth of voussoirs shall be as shownon the plans. Voussoirs shall be placed in the order indicated, shall be fullsize throughout and shall have bond not less than their thickness. Bedsshall be roughly pointed to bring them to radial planes. Radial joints shallbe in planes parallel to the transverse axis of the arch and, when measuredat the intrados, shall not exceed % inch in thickness. Joints perpendicularto the arch axis shall not exceed 1 inch in thickness when measured at theintrados. The intrados face shall be dressed sufficiently to permit the stoneto rest properly upon the centering. Exposed faces of the arch ring shallbe rock-faced with edges pitched to true lines.

The work shall be carried up symmetrically about the crown, the stonebeing laid in full mortar beds and the joints grouted where necessary.Pinning by the use of stone spalls will not be permitted.

Backing may consist of Class "B" concrete or of large stones shaped tofit the arch, bonded to the spandrels, and laid in full beds of mortar. Theextrados and interior faces of the spandrel walls shall be given a finishingcoat of 1:2% cement mortar which shall be trowelled smooth to receivethe waterproofing.

Arch centering, waterproofing, drainage and filling shall be as specifiedfor concrete arches.

CONSTRUCTION 67

2. 7. 9.—Pointing.

Pointing shall not be done in freezing weather or when the stonecontains frost.

Joints not pointed at the time the stone is laid shall be thoroughlywet with clean water and filled with mortar. The mortar shall be welldriven into the joints and finished with an approved pointed tool. Thewall shall be kept wet while pointing is being done and in hot or dryweather the pointed masonry shall be protected from the sun and kept wetfor a period of at least three days after completion.

After the pointing is completed and the mortar set, the wall shall be

thoroughly cleaned and left in a neat and workmanlike condition.


The quantity of stone masonry to be paid for under this item shall be

the number of cubic yards measured in the completed work and the limitingdimensions shall not exceed those shown upon the plans or fixed by theengineer. The contract price shall include all labor, tools, materials andother items incidental to the satisfactory completion of the work.

Concrete used in connection with rubble masonry shall be paid for asin the case of other concrete construction.

SECTION 8—Dry Rubble Masonry

2. 8. 1—Description.

Dry rubble masonry as here specified shall include the classes commonly known as coursed, random and random range work and shall consistof roughly squared and dressed stone laid without mortar.


Stone for this class of masonry shall conform to the requirements ofdivision IV.

2. 8. 3.—Size of Stone.

The stones shall conform in size to the requirements specified for"Mortar Rubble Masonry."

2. 8. 4.—Headers.

Headers shall conform to the requirements specified for "MortarRubble Masonry."

2. 8. 5.—Shaping Stone.

The stones shall be roughly squared on joints, beds and faces. Selectedstone, roughly squared and pitched to line, shall be used at all angles andends of walls.

2. 8. 6.—Laying Stone.

The masonry shall be laid to line and in courses roughly leveled up.The bottom or foundation courses shall be composed of large, selected stonesand all courses shall be laid with bearing beds parallel to the natural bedof the material. Face joints shall not exceed 1 inch in width.

In laying dry rubble masonry, care shall be taken that each stone takes

68 HIGHWAY BRIDGES

a firm bearing at not less than three separate points upon the underlyingcourse. Open joints, both front and rear, shall be "chinked" with spallsfitted to take firm bearing upon their top and bottom surfaces, for thepurpose of securing firm bearing throughout the length of the stone.

When required by the terms of the contract, the open joints on therear surfaces of abutments or retaining walls shall be "slushed" thoroughlywith mortar to prevent seepage of water through the joints.

2. 8. 7.—Copings, Bridge Seats and Backicalls.

Copings, bridge seats and backwalls, when used in connection with dryrubble masonry, shall conform to the requirements specified for "MortarRubble Masonry."


The quantity of stone masonry to be paid for under this item shalloe the number of cubic yards measured in the completed work and thelimiting dimensions shall not exceed those shown upon the plans or fixed bythe engineer. The contract price shall include all labor, tools, materialsand other expense incidental to the satisfactory completion of the work.

Concrete used in connection with rubble masonry shall be paid for asin the case of other concrete construction.

SECTION 9—Brick Masonry


Brick masonry shall consist of brick laid in cement mortar and shallinclude such construction with building brick or ornamental brick as maybe specified. Brick pavements are not included under this designation.


(a) Brick.Brick used for this class of work shall conform to the requirements

specified in Brick for Masonry, division IV.

(b) Mortar.The mortar used shall conform, as regards materials, proportions and

mixing, to the mortar specified for Ashlar Masonry. ,

2. 9. 3.—Construction.

The brick shall be laid in such manner as will thoroughly bond theminto the mortar by means of the "shove-joint" method; "buttered" orplastered joints will not be permitted. All brick must be thoroughlysaturated with water before being laid. The arrangement of headers andstretchers shall be such as will thoroughly bond the mass and, unless otherwise specified, brick work shall be of alternate headers and stretchers withconsecutive courses breaking joints. Other types of bonding, as for ornamental work, shall be as specified on the plans.

All joints shall be completely filled with mortar. They shall not be

less than % inch and not more than % inch in thickness and the thicknessshall be uniform throughout. All joints shall be finished properly as thework progresses and on exposed faces they shall be neatly struck, using the"weather" joint.

No spalls or bats shall be used except for shaping around irregular

CONSTRUCTION 69

openings or when unavoidable to finish out a course, in which case fullbricks shall be placed at the corners, the bats being placed in the interiorof the course.

Piers and walls may be built of solid brick work, or may consist of abrick shell backed with concrete or other suitable material as specified onthe plans. None but expert brick layers shall be employed on the workand all details of the construction shall be in accordance with the mostapproved practice and to the satisfaction of the engineer.

2. 9. 4.—Copings, Bridge Seats and Backwalls.

The tops of retaining walls, abutment wing walls and similarly exposedbrick work shall be provided, in general, with either a stone or concretecoping which shall project at least 1 inch beyond the face of the brick workand shall have a batter or drip bead, permitting water to drip clear of thewall. The coping upon an abutment backwall will commonly have no projection beyond its bridge seat face. When concrete is used it shall be ofClass "A" quality. For thin copings, mortar of the same proportions as

used for laying the brick may be used to produce precast sections not lessthan 3 feet nor more than 5 feet in length. No coping shall be less than4 inches thick.

Copings of piers and abutment bridge seats shall be of ashlar stonework or of Class "A" concrete and shall conform to the requirements forAshlar Masonry or Concrete Masonry as the plan may indicate. When notshown upon the plans, concrete shall be used.


The quantity of brick work to be paid for under this item shall be thenumber of cubic yards of brick masonry actually placed in the structurein accordance with the plans or as modified by written instructions fromthe engineer. This price shall include all labor, materials and other expenseincidental to the satisfactory completion of the work. Filling material forthe interior of the wall, when not of brick, and concrete or mortar copings,shall be paid for on the basis of the number of cubic yards actually placed.

SECTION 10—Steel Structures *

Fabrication

2. 10. 1.—Type of Fabrication.

Riveted construction is intended, unless otherwise indicated.

2. 10. 2.—Quality of Workmanship.

Workmanship and finish shall be equal to the best general practice inmodern bridge shops.

2. 10. 3.—Storage of Materials.

Structural material, either plain or fabricated, shall be stored at thebridge shop above the ground upon platforms, skids, or other supports.It shall be kept free from dirt, grease and other foreign matter, and shallbe protected as far as practicable from corrosion.

*Note: The fabrication of steel is covered by articles 2.10.1 to 2.10.43 and erection by

article 2.10.44 to 2.10.58.

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2. 10. 4.—Straighening Material.

Rolled material, before being laid off or worked, must be straight. Ifstraightening is necessary, it shall be done by methods that will not injurethe metal. Sharp kinks and bends shall be cause for rejection of thematerial.

2. 10. 5 Finish.

Portions of the work exposed to view shall be finished neatly. Shearing,flame cutting and chipping shall be done carefully and accurately.

2. 10. 6.—Rivet Holes.

All holes for rivets shall be either punched or drilled. Material forming parts of a member composed of not more than five thicknesses of metalmay be punched Me inch larger than the nominal diameter of the rivetswhenever the thickness of the metal is not greater than % inch for structural steel or % inch for alloy steel.

When there are more than five thicknesses or when any of the mainmaterial is thicker than % inch in carbon steel, or % inch in alloy steel,

or when required under article 2. 10. 9, all the holes shall be subpunchedor subdrilled $ie inch smaller and, after assembling, reamed Me inch larger,or drilled from the solid to Me inch larger, than the nominal diameter ofthe rivets.

2. 10. 7.—Punched Holes.

The diameter of the die shall not exceed the diameter of the punch bymore than Mo inch. If any holes must be enlarged to admit the rivets, theyshall be reamed. Holes must be clean cut, without torn or ragged edges.Poor matching of holes will be cause for rejection.

2. 10. 8 Reamed or Drilled Holes.

Reamed holes shall be cylindrical, perpendicular to the member and notmore than Me inch larger than the nominal diameter of the rivets. Wherepracticable, reamers shall be directed by mechanical means. Drilled holesshall be Mo inch larger than the nominal diameter of the rivet. Burrs onthe outside surfaces shall be removed. Poor matching of holes will be causefor rejection. Reaming and drilling shall be done with twist drills. Ifrequired by the engineer, assembled parts shall be taken apart for removalof burrs caused by drilling. Connecting parts requiring reamed or drilledholes shall be assembled and securely held while being reamed or drilledand shall be match marked before disassembling.

2. 10. 9.—Subpunching, Reaming and Shop Assembly.

Unless otherwise specified, holes in all field connections and field splicesof main truss or arch members, continuous beams, plate girders and rigidframes shall be subpunched (or subdrilled if subdrilling is required according to article 2. 10. 6) , and reamed while assembled in the shop. Theassembly, including camber, alignment, accuracy of holes and milled joints,shall be approved by the engineer before reaming is commenced.

Unless otherwise authorized by the engineer, each individual (fulllength) truss, arch, continuous beam or girder shall be assembled in theshop before reaming is commenced.

All holes for floor beam and stringer field end connections shall besubpunched and reamed to a steel template or reamed while assembled.

CONSTRUCTION 71

If additional subpunching and reaming is required, it shall be specifiedin the special provisions or on the plans.

2. 10. 10.—Accuracy of Punched and Subdrilled Holes.

All holes punched full size, subpunched, or subdrilled shall be so

accurately punched that after assembling (before any reaming is done)a cylindrical pin Vs inch smaller in diameter than the nominal size of thepunched hole may be entered perpendicular to the face of the member,without drifting, in at least 75 per cent of the contiguous holes in the sameplane. If the requirement is not fulfilled, the badly punched pieces will berejected. If any hole will not pass a pin %e inch smaller in diameter thanthe nominal size of the punched hole, this will be cause for rejection.

2. 10. 11.—Accuracy of Reamed and Drilled Holes.

When holes are reamed or drilled, 85 per cent of the holes in anycontiguous group shall, after reaming or drilling, show no offset greaterthan %2 inch between adjacent thicknesses of metal.

2. 10. 12.—Shop Assembling.

Shop assembly of trusses, arches, continuous beam spans and plategirders shall be according to article 2. 10. 9.

Complete shop assembly of an entire structure, including floor system,which may be necessary in the case of complicated designs shall be donewhen shown on the plans or when stipulated in the special provisions.

Surfaces of metal in contact shall be cleaned before assembling. Theparts of a member shall be assembled, well pinned, and firmly drawn together with bolts before reaming or riveting is commenced. Assembledpieces shall be taken apart, if necessary, for the removal of burrs andshavings produced by the reaming operation. The member shall be freefrom twists, bends, and other deformation.

Preparatory to the shop riveting of full-sized punched material, therivet holes, if necessary, shall be spear-reamed for the admission of therivets. The reamed holes shall not be more than Me inch larger than thenominal diameter of the rivets.

End connection angles, stiffener angles, and similar parts shall be carefully adjusted to correct positions and bolted, clamped, or otherwise firmlyheld in place until riveted.

Parts not completely riveted in the shop shall be secured by bolts, insofar as practicable, to prevent damage in shipment and handling.

2. 10. 13.—Camber Diagram.

A camber diagram shall be furnished the engineer, showing the camberat each panel point for each truss, taken from actual measurements whilethe truss is assembled.

2. 10. 14.—Drifting of Holes.

The drifting done during assembling shall be only such as to bringthe parts into position, and not sufficient to enlarge the holes or distort themetal. If any holes must be enlarged to admit the rivets, they shall be

reamed.

2. 10. 15.—Match-Marking.

Connecting parts assembled in the shop for the purpose of reamingholes in field connections shall be match-marked, and a diagram showingsuch marks shall be furnished to the engineer.

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2. 20. 16.—Rivets.

The size of rivets called for on the plans shall be the size before heating.Rivet heads shall be of standard shape, unless otherwise specified, and

of uniform size for the same diameter of rivet. They shall be full, neatlymade, concentric with the rivet holes, and in full contact with the surfaceof the member.

2. 10. 17 Field Rivets.

Sufficient field rivets shall be furnished to rivet the entire structurewith an ample surplus to replace all rivets burned, lost or cut out.

2. 10. 18.—Bolts and Bolted Connections.

(a) General.

Bolted connections shall not be used unless shown on the plans. Wherebolted connections are permitted, the bolts furnished shall be unfinishedbolts (ordinary rough or machine bolts). Turned bolts shall be providedif shown on the plans or if required by the special provisions. Specialribbed drive fit bolts may be substituted for turned bolts upon writtenapproval of the engineer.

The holes shall be truly cylindrical. The size of holes shall be He inchgreater than the nominal diameter of the bolts and shall make a drivingfit with the bolts. Holes shall be at right angles to the surface of the metalso that both head and nut will bear squarely against the metal. Boltsshall be driven accurately into the holes without damaging the thread. Asnap shall be used to prevent damaging the heads.

The heads and nuts shall be drawn tight against the work with a

suitable wrench not less than 15 inches long. Bolt heads shall be tappedwith a hammer while nut is being tightened. Where bolts are to be usedin beveled surfaces, beveled washers shall be provided to give full bearingto the head or nut. Ribbed bolts shall be furnished in the same numberand in nominal sizes not smaller than the rivets for which they are substituted. They shall be furnished in sufficient variety of lengths that whendrawn tight the fluted shank will fill the hole in the work and the threadwill completely fill the nut with not more than one thread protruding. Allbolts shall have cut threads neatly and accurately finished.

If for any reason the bolts twist before drawing tight, the hole shallbe carefully reamed and the bolt replaced with a new bolt of diameter tofit properly in the hole.

The contractor shall provide and supply himself with oversize boltsfor this replacement in an amount not less than 10 per cent of the numberof ribbed bolts specified.

The nuts of unfinished, turned bolts and ribbed bolts shall be effectuallylocked after they have been finally tightened.

(b) Unfinished Bolts.

Unfinished bolts shall be standard bolts with hexagonal heads andnuts. The diameter of the bolt holes shall be inch greater than thediameter of the bolts used. Bolts transmitting shear shall be threaded tosuch a length that not more than one thread will be within the grip ofthe metal. The bolts shall be of such length that they will extend entirelythrough their nuts, but not more than % inch beyond them. The numberof bolts furnished shall be 5 per cent more than the actual number shownon the plans for each size and length.

CONSTRUCTION 78

(c) Turned Bolts.

Holes for turned bolts shall be carefully reamed and the bolts turnedto a driving fit with the threads entirely outside of the holes and a washershall be used. The heads and nuts shall be hexagonal.

One-fourth inch nut locks shall be used on all turned bolts unlessotherwise specified on the plans. Turned bolts shall be finished by a

finishing cut.

(d) Special Ribbed Bolts.

Ribbed bolts, with drive fit, shall be used only where called for on theplans. Ribbed bolts may be substituted for field rivets in locations where,in the opinion of the engineer, it is impractical to drive rivets.

2. 10. 19 Riveting.

Rivets shall be heated uniformly to a "light cherry red color" and shallbe driven while hot. Any rivet whose point is heated more than the remainder shall not be driven. When a rivet is ready for driving, it shallbe free from slag, scale and other adhering matter. Any rivet which, inthe opinion of the engineer, is scaled excessively, will be rejected.

All rivets that are loose, burned, badly formed, or otherwise defectiveshall be removed and replaced with satisfactory rivets. Any rivet whosehead is defective in size or whose head is driven off center will be considered defective and shall be removed. Stitch rivets that are loosenedby driving of adjacent rivets shall be removed and replaced with satisfactory rivets. Caulking, recupping or double gunning of rivet heads willnot be permitted.

Shop rivets shall be driven by direct-acting rivet machines whenpracticable. Approved beveled rivet sets shall be used for forming rivetheads on sloping surfaces. When the use of a direct-acting rivet machineis not practicable, pneumatic hammers of approved size shall be used.Pneumatic bucking tools will be required when, in the opinion of the engineer,the size and length of the rivets warrant their use.

Rivets may be driven cold provided their diameter is not over % inch.

2. 10. 20 Edge Planing.

Sheared edges of plates more than % inch in thickness and carryingcalculated stress shall be planed to a depth of V* inch. Re-entrants cutsshall be filleted before cutting.

2. 10. 21 Weld».

Welding of steel structures, when authorized in accordance with theprovisions of division III, shall conform to Specifications for Welded Highway and Railway Bridges of the American Welding Society.

If a fabricating shop prequalifies its metal-arc welding operators according to the standard qualification procedure of the American WeldingSociety and certifies to the engineer that an operator working on the structure has been prequalified within twelve months previous to the beginningof work on the subject structure, the engineer may consider such operatorqualified. The certificate shall state that such operator shall have been

doing satisfactory welding of the required type within the three monthperiod previous to the subject work. A certification shall be submittedfor each operator and for each project, stating, the name of the operator,

74 HIGHWAY BRIDGES

the name and title of the person who conducted the examination, the kindof specimens, the positions of welds, the results of the tests and the dateof the examination. Such a certification of prequalification may also be

accepted as proof that an operator on field welding is qualified, if thecontractor who submits it is properly staffed and equipped to conduct suchan examination or if the examining and testing is done by a recognizedagency which is staffed and equipped for such purpose.

2. 10. 22.—Flame Cutting.

Steel or wrought-iron may be flame cut, provided a smooth surfaceis secured by the use of a mechanical guide. Flame cutting by hand shallbe done only where approved by the engineer and the surface shall be madesmooth by planing, chipping or grinding. The cutting flame shall be so

adjusted and manipulated as to avoid cutting beyond the prescribed lines.Re-entrant cuts shall be filleted to a radius of not less than % inch.

In the case of silicon steel, flame cut edges shall be removed to a depthof at least % inch, by milling, chipping, or grinding.

2. 10. 23.—Facing of Bearing Surfaces.

The top and bottom surfaces of steel slabs and base plates and capplates of columns and pedestals shall be planed, or else the plates or slabshot straightened. Parts of members in contact with them shall be faced.

Sole plates of beams and girders shall have full contact with theflanges. Sole plates and masonry plates shall be planed or hot straightened.Cast pedestals shall be planed on surfaces to be in contact with steeland shall have the surface to be in contact with masonry, rough-finished.

Surfaces of bronze bearing plates intended for sliding contact shallbe finished.

In planing the surfaces of expansion bearings the cut of the tool shallbe in the direction of expansion.

2. 10. 24.—Abutting Joints.

Abutting joints in compression members and girder flanges, and intension members where so specified on the drawings, shall be faced andbrought to an even bearing. Where joints are not faced, the opening shallnot exceed Vs inch.

2. 10. 25.—End Connection Angles.

Floor beams, stringers and girders having end connection angles shallbe built to exact length back to back of connection angles. If end connections are faced, the finished thickness of the angles shall not be lessthan that shown on the detail drawings.

2. 10. 26.—Lacing Bars.

The ends of lacing bars shall be neatly rounded unless another formis required.

2. 10. 27.—Finished Members.

Finished members shall be true to line and free from twists, bends andopen joints.

2. 10. 28 Web Plates.

In girders having no cover plates and not to be encased in concrete,the top edge of the web plate shall not extend above the backs of the flange

CONSTRUCTION 75

angles and shall not be more than % inch below at any point. Any portionof the plate projecting beyond the angles shall be chipped flush with thebacks of the angles. Web plates of girders having cover plates may be

Vz inch less in width than the distance back to back of flange angles.

Splices in webs of girders without cover plates shall be sealed on thetop by welding.

At web splices, the clearance between the ends of the web plates shallnot exceed % inch. The clearance at the top and bottom ends of the websplice plates shall not exceed V* inch.

2. 10. 29. —Bent Plates.

Cold-bent load-carrying rolled-steel plates shall conform to thefollowing :

(1) They shall be so taken from the stock plates that the bend-line willbe at right angles to the direction of rolling.

(2) The radius of bends, measured to the concave face of the metal,shall not be less and preferably shall be greater than shown in the followingtable, in which "T" is the thickness of the plate:

If a shorter radius is essential, the plates shall be bent hot. Hot-bentplates shall conform to requirement (1) above.

(3) Before bending, the corners of the plate shall be rounded to aradius of Me inch throughout that portion of the plate at which the bendingis to occur.

2. 10. 30—Fit of Stiffeners.

End stiffener angles of girders and stiffener angles intended as supports for concentrated loads shall be milled or ground to secure an evenbearing against the flange angles. Intermediate stiffener angles shall fitsufficiently tight to exclude water after being painted. Fillers understiffeners shall fit within Vt inch at each end.

Welding will be permitted in lieu of milling or grinding if noted on theplans or specified in the special provisions as provided in division III.Welding transversely across the tension flanges of beams or girders, whichhave a flange stress of more than 75 per cent of their designed capacity,will not be permitted.

2. 10. 31.—Eyebars.

Eyebars shall be straight, true to size, and free from twists, foldsin the neck and head, and other defects. The heads shall be made byupsetting and rolling or forging, and not by welding. The form of theheads will be determined by the dies in use at the works where the eyebarsare made, if they are satisfactory to the engineer. The thickness of thehead and neck shall not overrun more than Mg inch.

Eyebars that are to be placed side by side in the structure shall bebored so accurately that upon being placed together, pins tys inch lessin diameter than the pin holes will pass through the holes at both endsat the same time without driving.

MinimumAngle through which plate is bent radius

1.0 T1.5 T2.0 T

91 degrees to 120 degrees121 degrees to 150 degrees

76 HIGHWAY BRIDGES

2. 10. 32.—Annealing.

Before boring, eyebars shall be annealed to produce the requiredphysical qualities and shall be straightened. Proper instruments shall be

provided for determining at any time the temperature of the bars.Other steel that has been heated partially shall be annealed, unless

it is to be used in minor parts. Crimped stiffeners need not be annealed.

2. 10. 33 Pins and Rollers.

Pins and rollers shall be accurately turned to the dimensions shownon the drawings and shall be straight, smooth, and free from flaws.

Pins and rollers more than 7 inches in diameter shall be forged andannealed.

In pins larger than 9 inches in diameter, a hole not less than 2 inchesin diameter shall be bored full length along the axis after the forging hasbeen allowed to cool to a temperature below the critical range under suitable conditions to prevent injury by too rapid cooling, and before beingannealed.

2. 10. 34.—Boring Pin Holes.

Pin holes shall be bored true to the specified diameter, smooth andstraight, at right angles with the axis of the member and parallel witheach other unless otherwise required. The final surface shall be producedby a finishing cut.

The distance outside to outside of holes in tension members and insideto inside of holes in compression members shall not vary from that specifiedmore than %2 inch. Boring of holes in built-up members shall be doneafter the riveting is completed.

2. 10. 35.—Pin Clearances.

The diameter of the pin hole shall not exceed that of the pin by morethan %o inch for pins 5 inches or less in diameter, or ^ inch for larger pins.

2. 10. 36.—Screw Threads.

Threads for all bolts and pins for structural steel construction shallconform to the American National Coarse Thread Series, Class 2, free fit,

except that the pin ends having a diameter of 1% inches or more shall be

threaded six threads to the inch.

2. 10. 37 Pilot and Driving Nuts.

Two pilot nuts and two driving nuts for each size of pin shall be

furnished, unless otherwise specified.

2. 10. 38.—Notice of Beginning of Work.

The contractor shall give the engineer ample notice of the beginningof work at the mill or in the shop, so that inspection may be provided.The term "mill" means any rolling mill or foundry where material forthe work is to be manufactured. No material shall be manufactured orwork done in the shop before the engineer has been so notified.

2. 10. 39. —Facilities for Inspection.

The contractor shall furnish facilities for the inspection of materialand workmanship in the mill and shop, and the inspectors shall be allowedfree access to the necessary parts of the works.

CONSTRUCTION 77

2. 10. 40.— Inspector's Authority.

Inspector shall have the authority to reject any material or workwhich does not meet the requirements of these specifications. In case ofdispute the contractor may appeal to the engineer, whose decision shallbe final.

2. 10. 41 Mill Orders.

The contractor shall furnish the engineer with as many copies of millorders as the engineer may direct.

2. 10. 42 Weighing of Members.

In case it is specified that any part of the material is to be paid for byactual weight, finished work shall be weighed in the presence of the inspector,if practicable. In such case, the contractor shall supply satisfactoryscales and shall perform all work involved in handling and weighing thevarious parts.

2. 10. 43.—Marking and Shipping.

Each member shall be painted or marked with an erection mark foridentification and an erection diagram shall be furnished with erectionmarks shown thereon.

The contractor shall furnish to the engineer as many copies ofmaterial orders, shipping statements and erection diagrams as the engineermay direct. The weights of the individual members shall be shown on thestatements. Members weighing more than 3 tons shall have the weightsmarked thereon. Structural members shall be loaded on trucks or cars insuch a manner that they may be transported and unloaded at their destination without being excessively stressed, deformed or otherwise damaged.

Bolts and rivets of one length and diameter and loose nuts or washersof each size shall be packed separately. Pins, small parts and packagesof bolts, rivets, washers and nuts shall be shipped in boxes, crates, kegsor barrels, but the gross weight of any package shall not exceed 300 pounds.A list and description of the contained material shall be plainly marked on

the outside of each shipping container.

ERECTION

2. 10. 44.—Erection of Structure.

If the substructure and superstructure are built under separate contracts, the commission will provide the masonry, constructed to correct linesand elevations and properly finished, and will establish the lines andelevations required for setting the steel.

The contractor shall erect the metal work, remove the temporary construction, and do all work required to complete the bridge or bridges as

covered by the agreement, including the removal of the old structure orstructures if stipulated, all in accordance with the plans and thesespecifications.

2. 10. 45.—Plans.

If the fabrication and erection of the superstructure are done underseparate contracts, the commission will furnish detail plans for the bridgeor bridges to be erected, including shop details, camber diagrams, erection

78 HIGHWAY BRIDGES

diagrams, list of field rivets and bolts, and copy of shipping statementsshowing a list of parts and their weights.

2. 10. 46.—Plant

The contractor shall provide the falsework and all tools, machineryand appliances, including drift pins and fitting-up bolts, necessary for theexpeditious handling of the work.

2. 10. 47.—Delivery of Materials.

If the contract is for erection only, the contractor shall receive thematerials entering into the finished structure, free of charges at the placedesignated and loaded or unloaded as specified. The contractor shall unloadpromptly upon delivery any material delivered on railroad cars or bargeswhich he is required to unload, otherwise he shall be responsible fordemurrage eharges.

2. 10. 48.—Handling and Storing Materials.

Material to be stored shall be placed on skids above the ground. Itshall be kept clean and properly drained. Girders and beams shall be placedupright and shored. Long members, such as columns and chords, shall be

supported on skids placed near enough together to prevent injury fromdeflection. If the contract is for erection only the contractor shall checkthe material turned over to him against the shipping lists and reportpromptly in writing any shortage or injury discovered. He shall be responsible for the loss of any material while in his care, or for any damagecaused to it after being received by him.

2. 10. 49.—Falsework.

The falsework shall be properly designed and substantially constructedand maintained for the loads which will come upon it. The contractor, ifrequired, shall prepare and submit to the engineer for approval, plans forfalsework or for changes in an existing structure necessary for maintainingtraffic Approval of the contractor's plans shall not be considered asrelieving the contractor of any responsibility.

2. 10. SO. —Methods and Equipment.

Before starting the work of erection, the contractor shall inform theengineer fully as to the method of erection he proposes to follow, and theamount and character of equipment he proposes to use, which shall be

subject to the approval of the engineer. The approval of the engineer shallnot be considered as relieving the contractor of the responsibility for thesafety of his method or equipment or from carrying out the work in fullaccordance with the plans and specifications. No work shall be done untilsuch approval by the engineer has been obtained.

2. 10. 51.—Bearings and Anchorage.

Masonry bearing plates shall not be placed upon bridge seat bearingareas which are improperly finished, deformed or irregular. Bearing platesshall be set level in exact position and shall have a full and even bearingupon the masonry. Unless otherwise directed by the engineer, they shallbe placed on a layer of canvas and red lead applied as follows:

Thoroughly swab the bridge seat bearing area with red lead paintand place upon it three layers of 12 to 14 ounce duck, each layer being

CONSTRUCTION 79

thoroughly swabbed on its top surface with red lead paint. Place thesuperstructure shoes or pedestals in position while the paint is plastic. Asan alternate to canvas and red lead, sheet lead may be used if called foron the plans.

The contractor shall drill the holes and set the anchor bolts, exceptwhere the bolts are built into the masonry. The bolts shall be set accuratelyand fixed with Portland cement grout completely filling the holes. Thelocation of the anchor bolts in relation to the slotted holes in the expansionshoes shall correspond with the temperature at the time of erection. Thenuts on anchor bolts at the expansion ends of spans shall be adjusted topermit the free movement of the span.

2. 10. 52.—Straightening Bent Material.

The straightening of plates and angles or other shapes shall be doneby methods not likely to produce fracture or other injury. The metalshall not be heated unless permitted by the engineer, in which case theheating shall not be to a higher temperature than that producing a dark"cherry red" color. After heating, the metal shall be cooled as slowly aspossible.

Following the straightening of a bend or buckle, the surface of themetal shall be carefully inspected for evidence of fracture.

2. 10. 53.—Assembling Steel.

The parts shall be accurately assembled as shown on the plans andany match-marks shall be followed. The material shall be carefully handledso that no parts will be bent, broken, or otherwise damaged. Hammeringwhich will injure or distort the members shall not be done. Bearingsurfaces and surfaces to be in permanent contact shall be cleaned beforethe members are assembled. Unless erected by the cantilever method,truss spans shall be erected on blocking so placed as to give the trussesproper camber. The blocking shall be left in place until the tension chordsplices are fully riveted and all other truss connections pinned and bolted.Rivets in splices of butt joints of compression members and rivets in railingsshall not be driven until the span has been swung. Splices and fieldconnections shall have one half of the holes filled with bolts and cylindricalerection pins (half bolts and half pins) before riveting. Splices andconnections carrying traffic during erection shall have three-fourths of theholes so filled.

Fitting-up bolts shall be of the same nominal diameter as the rivets,and cylindrical erection pins shall be Vm inch larger.

2. 10. 54.—Riveting.

Pneumatic hammers shall be used for field riveting, except when the

use of hand tools is permitted by the engineer. Rivets larger than % Inchin diameter shall not be driven by hand. Cup-faced dollies, fitting thehead closely to insure good bearing, shall be used. Connections shall be

accurately and securely fitted up before the rivets are driven. Driftingshall be only such as to draw the parts into position and not sufficient toenlarge the holes or distort the metal. Unfair holes shall be reamed or

drilled. Rivets shall be heated uniformly to a light "cherry red" color andshall be driven while hot. They shall not be overheated or burned. Rivetheads shall be full and symmetrical, concentric with the shank, and shall

have full bearing all around. They shall not be smaller than the heads of

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the shop rivets. Rivets shall be tight and shall grip the connected partssecurely together. Caulking or recupping will not be permitted. In removing rivets, the surrounding metal shall not be injured; if necessary, theyshall be drilled out.

2. 10. 55.—Pin Connections.

Pilot and driving nuts shall be used in driving pins. They shall be

furnished by the contractor without charge. Pins shall be so driven thatthe members will take full bearing on them. Pin nuts shall be screwedup tight and the threads burred at the face of the nut with a pointed tool.

2. 10. 56.—Misfits.The correction of minor misfits involving non-harmful amounts of

reaming, cutting and chipping will be considered a legitimate part of theerection. However, any error in the shop fabrication or deformation resulting from handling and transportation which prevents the proper assemblingand fitting up of parts by the moderate use of drift pins or by a moderateamount of reaming and slight chipping or cutting, shall be reported immediately to the inspector and his approval of the method of correction obtained.The correction shall be made in his presence. If the contract provides forcomplete fabrication and erection the contractor shall be responsible forall misfits, errors and injuries and shall make the necessary correctionsand replacements. If the contract is for erection only the inspector, withthe cooperation of the contractor, shall keep a correct record of labor andmaterials used and the contractor shall render within 30 days an itemizedbill for the approval of the engineer.

2. 10. 57.—Removal of Old Structure and Falsework.

If stipulated in the agreement, the contractor shall dismantle the oldstructure which, unless otherwise provided, shall be the property of thecommission, and shall store the material in the immediate vicinity of thebridge site as the engineer may direct. If the old structure is to be

re-erected, it shall be dismantled without unnecessary damage and the partsmatch-marked and carefully piled.

Upon completion of the erection and before final acceptance, the contractor shall remove all falsework, excavated or useless materials, rubbishand temporary buildings, replace or renew any fences damaged and restorein an acceptable manner all property, both public and private, which mayhave been damaged during the prosecution of this work, and shall leavethe bridge site and adjacent highway in a neat and presentable conditionsatisfactory to the engineer. All excavated material or falsework placedin the stream channel during construction shall be removed by the contractorbefore final acceptance.

2. 10. 58.—Basis of Payment.

The contract price for fabrication and erection of structural steel shallinclude all labor, materials, transportation, and shop and field paintingnecessary for the proper completion of the work in accordance with thecontract.

The contract price for fabrication without erection shall include alllabor and materials necessary for fabrication, shop painting, shipping anddelivery at the place designated.

Payment will be made on a pound-price or a lump-sum basis, as required

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by the terms of the contract, but unless stipulated otherwise, it shall beon a pound-price basis. For the purpose of payment, such items as bearingplates, pedestals, etc., shall unless otherwise provided, be considered asstructural steel even though made of other materials.

Under contracts containing an item for structural steel, all minor metalparts other than metal reinforcement, such as expansion joints, drains,bolts, etc., which are embedded in concrete shall be paid for as structuralsteel.

2. 10. 59.—Payment for Test Eyebars.

Full-size eyebars which are tested and meet the requirements of thesespecifications shall be paid for by the purchaser at the same rate as forthe structure. Bars which fail to meet these requirements, and all barsrejected as a result of tests, shall not be paid for by the purchaser.

2. 10. 60.—Pay Weight.

The payment in pound-price contracts shall be based on the weight ofmetal in the fabricated structure, including field rivets shipped. However,any weight in excess of 1% per cent above the computed weight for thewhole structure shall not be included in the pay weight. The weight oferection bolts, field paint, boxes, crates and other containers used forpacking, and materials used for supporting members during transportation,shall not be included.

The weight paid for shall be the shop scale weight unless otherwiseprovided. If specified in the contract or permitted by the engineer, computed weights, obtained as hereinafter described, may be made the basisof payment.

2. 10. 61.—Variance in Weight.

If the scale weight of any member is less than 97% per cent of thecomputed weight, the member may be rejected. This applies to both pound-price and lump-sum contracts.

2. 10. 62.—Computed Weight.

The weight shall be computed on the following basis:

(1) Unit weights, per cubic foot—

Aluminum, cast or wrought 173.0Bronze, cast 536.0Copper-alloy 536.0Copper sheet 558.0Iron, cast 445.0Iron, malleable 470.0Iron, wrought 487.0Lead, sheet 707.0Steel, cast, copper bearing, silicon, nickel and stainless . . 490.0Zinc 450.0

(2) The weights of rolled shapes, and of plates up to and including36 inches in width, shall be computed on the basis of their nominal weightsand dimensions, as shown on the approved shop drawings, deducting forcopes, cuts and all open holes, except rivet holes.

To the nominal weights of plates more than 36 inches in width, thereshall be added one-half the allowed percentage of overrun in weight givenin the Specifications for Steel for Bridges and Buildings of the A. S. T. M.,Designation A 7-46.

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(3) The weight of all rivet heads, both field and shop, shall be includedon the basis of the following weights:

(4) The weight of castings shall be computed from the dimensionsshown on the approved shop drawings, deducting for open holes. To thisweight shall be added 10 per cent allowance for fillets and overrun.

(5) To the total computed weight of metal shall be added 0.4 of 1 percent as an allowance for shop paint.

(6) Railing. —The weight of railing shall be included unless it is paidfor on a linear foot basis.

(7) Steel Grid Flooring. —Steel grid flooring shall be measured andpaid for as structural steel only if so specified in the special provisions.

(8) The weight of steel or brass shims required shall be included. Theweight of brass shims shall be calculated on the basis of the unit weightof brass.

SECTION 1 1—Bronze or Copper-Alloy Bearing and Expansion Plates

2. 11. 1.—General.

Plates shall be of the kind of metal specified in the special provisionsor as shown on the plans.


The material shall conform to the requirements of division IV.

2. 11. 3.—Bronze Plates.

Plates shall be cast according to details shown on the plans. Slidingsurfaces shall be planed parallel to the movment of the spans and polishedunless detailed otherwise.

2. 11. 4.—Copper-Alloy Plates.

Plates shall be furnished according to details shown on the plans.Finishing of the rolled plates will not be required provided they have a

plane, true and smooth surface.

2. 11. S Placing.

Bearing plates shall be accurately set in correct position as shown onthe plans and shall have a uniform bearing over the whole area. Provisionshall be made to keep the plates in correct position as the concrete is beingplaced.


The weight to be paid for shall be the inspector's certified shop scaleweight of the plates as placed in the structure, unless otherwise provided.If specified in the contract or permitted by the engineer, computed weights,obtained as herein described, may be made the basis of payment.

Diameter of rivet,inches

Weight per 100heads, pounds

47

12

18263648

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Payment shall be made at the contract price per pound. Payment shallinclude the furnishing of material and all labor and incidental work thatis required.

SECTION 12—Steel Grid Flooring

2. 12. 1.—General.

Steel grid flooring shall be of the open type, or the concrete filled typeas specified in the special provisions or as shown on the plans.

The floor shall meet the requirements for the design of steel grid floors,division III. Before fabrication or construction is undertaken the contractor shall submit complete shop and assembly details to the engineer forapproval and his approval secured.


Materials shall conform to the requirements for steel grid floors,division IV.

2. 12. 3.—Arrangement of Sections.

Where the main elements are normal to center line of roadway, theunits generally shall be of such length as to extend over the full width ofthe roadway for roadways up to 40 feet, but in every case the units shallextend over at least three panels. Where joints are required, the ends ofthe main floor members shall be welded at the joints over their full cross-sectional area or otherwise connected to provide full continuity.

Where the main elements are parallel to center line of roadway, thesections shall extend over not less than three panels, and the ends ofabutting units shall be welded over their full cross-sectional area or otherwise connected to provide full continuity in accordance with the design.

2. 12. 4.—Provision for Camber.

Unless otherwise provided on the plans, provision for camber shall be

made as follows:Steel units so rigid that they will not readily follow the camber required

shall be cambered in the shop. To provide a bearing surface parallel tothe crown of the roadway the stringers shall be canted or provided withshop-welded beveled bearing bars. If beveled bars are used they shall be

placed along the center line of the stringer flange, in which case the designspan length shall be governed by the width of the bearing bar instead ofby the width of the stringer flange.

Longitudinal stringers shall be mill cambered or provided with bearingstrips so that the completed floor after dead-load deflection shall conformto the longitudinal camber shown on the plans.

2. 12. S.—Field Assembly.

Areas of considerable size shall be assembled before the floor is weldedto its supports. The main elements shall be made continuous and sectionsshall be connected together along their edges by welding of bars or byriveting them. The connections shall meet with the approval of the engineer. The rivets may be cold driven.

2. 12. 6.—Connection to Supports.

The floor shall be connected to its steel supports by welding. Beforeany welding is done the floor shall either be loaded to make a tight joint

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with full bearing or it shall be clamped down. The location, length andsize of the welds shall be subject to the approval of the engineer, but in nocase shall they be less than the manufacturer's standards.

The ends of all the main steel members of the slab shall be securelyfastened together at the sides of the roadway for the full length of thespan by means of steel plates or angles welded to the ends of the mainmembers, or by thoroughly encasing the ends with concrete.

2. 12. 7.—Welding.

All shop and field welding shall be done in accordance with the currentspecifications of "The American Welding Society for Welded Highwayand Railway Bridges."

Surfaces to be welded shall be free from paint, grease, loose scale, rustand other material that will prevent a proper weld. A thin coating oflinseed oil, without pigment, need not be removed. Any clinkers or slagcaused by flame cutting or other causes shall be removed before welding.

2. 12. 8.—Repairing Damaged Galvanized Coatings.

All galvanizing that has been chipped off or damaged in handling ortransporting or in welding or riveting shall be repaired by field galvanizingby the application of a paste composed of approved zinc powder and fluxwith a minimum amount of water. The places to be coated shall be

thoroughly cleaned, including removal of slag on welds, before the paste isapplied. The surface to be coated shall first be heated with a torch toa sufficient temperature so that all metallics in the paste are melted whenapplied to the heated surface. Extreme care shall be taken to see that thegalvanized surfaces are not damaged by the torch. The flux in the pastewill cause a black substance to appear on the surface of the coated parts,and this black substance shall be removed by wiping off with waste or bythe quick application of cold water.

2. 12. 9.—Concrete Filler.

Floor types with bottom flanges not in contact shall be provided withbottom forms of metal or wood to retain the concrete filler without excessiveleakage.

If metal form strips are used they shall fit tightly on the bottom flangesof the floor members and be placed in short lengths so as to extend onlyabout 1 inch onto the edge of each support, but in all cases the forms shallbe such as will result in adequate bearing of slab on the support.

The concrete shall be mixed, placed and cured in accordance with thespecification for Concrete Masonry, division II. The concrete shall be

thoroughly compacted by vibrating the steel grid floor. The vibratingdevice and the manner of operating it shall be subject to the approval ofthe engineer.

2. 12. 10 Painting.

flooring furnished without galvanizing but with a shop coat of paintshall be given two field coats of paint in accordance with the specificationfor Painting Metal Structures.

If a structural steel plate is used on the bottom of a filled type floor,the bottom surface of the plate shall be painted one shop coat and two fieldcoats of paint in accordance with specification for Painting Metal Structures,

division II.

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2. 12. 11.—Method of Measurement and Basis of Payment.

Payment for steel grid floor, open or concrete filled type, shall includethe furnishing of all materials, equipment, tools, and labor necessary forthe satisfactory completion of the work. Payment will be made on the basisof the number of square feet of steel grid floor complete in place, unlessotherwise specified.

SECTION 13—Railings

2. 13. 1.—General.

Railings for bridges, wing walls, retaining walls, etc., shall include allwork constructed above the top of the roadway curb or of the sidewalksurface. Entrance posts, pylons, and other items integral with the railingshall, for the purpose of measurement and payment, be included as railingunless otherwise specified. This item shall include the furnishing of allmaterial, equipment, tools, supplies, and labor necessary for the properconstruction of the handrails and parapets, as shown on the plans orprovided for in the special provisions.

2. 13. 2 Materials.

All materials shall conform to the requirements of division IV. Unlessotherwise specified, all pipe used for railing shall be wrought iron. Ifgalvanizing is required, it shall be specified in the special provisions orcalled for on the plans. Paint shall be as specified for Metals, division IV.

2. 13. 3.—Line and Grade.

The line and grade of the railing shall be true to that shown on theplans, and not follow any unevenness in the superstructure. Unless otherwise specified or shown on the plans, the handrail and curbs on bridges,whether superelevated or not, shall be vertical.

Metal Railing2. 13. 4.—Construction.

Fabrication and erection shall be done in accordance with the requirements for Steel Structures, division II. In the case of welded railing, afterwelding, all exposed joints shall be finished by grinding or filling to givea neat appearing job.

Metal railings shall be carefully adjusted prior to fixing in place toinsure proper matching at abutting joints and correct alignment andcamber throughout their length. Holes for field connections shall be drilledwith the railing in place in the structure at proper grade and alignment.Welding may be substituted for rivets in field connections with the approvalof the engineer.

2. 13. 5.—Painting.

Unless otherwise specified, metal railing shall be given one shop coatof paint, and three coats of paint after erection. Painting shall conformto the requirements for Painting Metal Structures, division II.

Concrete Railing2. 13. 6.—General.

In no case shall concrete railings be placed until the centering orfalsework for the span has been released, rendering the span self-supporting.

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Except as modified herein, materials shall conform to the requirementsof division IV.

2. 13. 8—Railings Cast in Place.

The portion of the railing or parapet which is to be cast in place shallbe constructed in accordance with the requirements for Concrete Masonry,division II. Special care shall be exercised to secure smooth and tight-fitting forms which can be rigidly held in line and grade and removedwithout injury to the concrete.

Forms shall either be of single width boards or shall be lined withsuitable material which shall meet with the approval of the engineer. Formjoints in plane surfaces will not be permitted.

All moldings, panel work, and bevel strips shall be constructed according to the detail plans with neatly mitered joints and all corners in thefinished work shall be true, sharp and clean-cut and shall be free fromcracks, spalls or other defects.

2. 13. 9.—Precast Rails.

Moist tamped mortar precast members shall be made of a mixture ofcement and sand approximately in the proportions of one part of cement totwo and one-half parts of sand. The sand shall be specially selected forcolor and grading. The sand shall be screened through a screen having% inch square meshes, and all oversize particles shall be discarded. Onlysufficient water shall be used in mixing to permit the immediate removalof the member from the mold.

Moist tamped mortar precast members shall be cast in mortar-tightmetal or metal-lined molds. The precast members shall be removed fromthe molds as soon as practicable and shall be kept damp for a period of atleast 10 days. During this period they shall be protected from the sun andfrom wind. Any members that show checking or soft corners or surfacesshall be rejected. The method of storage and handling shall be such asto preserve true and even edges and corners, and any precast memberswhich become chipped, marred, or cracked before or during the process ofplacing shall be rejected.

In the construction of cast-in-place railing caps and copings built inconnection with precast balusters, the balusters shall be protected fromstaining and disfigurement during the process of placing and finishing theconcrete.

2. 13. 10 Surface Finish.

The surfaces of railings shall conform to the requirements of thespecification for Concrete Masonry, division II.

2. 13. 11.—Expansion Joints.Expansion joints shall be so constructed as to permit freedom of

movement. After all other work is completed, all loose or thin shells ofmortar likely to spall under movement shall be carefully removed from allexpansion joints by means of a sharp chisel.

Stone and Brick Railing2. 13. 12.—General.

Unless otherwise specified, the materials used in masonry or brickrailings and parapets shall conform to, and the work shall be done in

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accordance with, the requirements of these specifications for the particularclass of work involved. The work shall be done in accordance with thedetailed plans, the workmanship shall be first class in every particular, andthe finished construction shall be neat in appearance and true to line andgrade.

Wood Railing2. 13. 13.—General.

Wood railings shall be constructed according to the requirements forTimber Structures, division II.


Payment for railing shall include all materials, tools, equipment, supplies, labor, and other costs necessary for the satisfactory completion ofthe work.

The reinforcing steel included in payment for rail shall be determinedas follows: The portion of slab or beam bars which project into the handrailshall be paid for as metal reinforcement, but the portion of the handrailsteel which extends into the slab or beams shall be considered as part ofthe handrail.

Payment will be made on the basis of the number of linear feet ofrailing measured along the center line of the railing. When steel railingsare shown on steel structures and no separate bid is taken for railing, therailing will be paid for at the price bid per pound for structural steel.

SECTION 14—Painting Metal Structures

2. 14. 1.—General.

The painting of metal structures shall include, unless otherwise provided in the contract, the preparation of the metal surfaces, the application,protection and drying of the paint coatings, and the supplying of all tools,tackle, scaffolding, labor and materials necessary for the entire work.

2. 14. 2.—Paint.The paint used shall conform to the requirements of division IV and

as specified in the special provisions or on the plans.

2. 14. 3.—Number of Coats and Color.

All steel shall be painted one shop or prime coat, and with not less thantwo field coats, as specified in division IV. The color shall be as specifiedor determined by the engineer. The coats shall be sufficiently different incolor to permit detection of incomplete application.

2. 14. 4.—Mixing of Paint.

Paint shall be factory mixed except as provided in division IV. Allpaint shall also be field mixed before applying in order to keep the pigmentsin uniform suspension.

2. 14. 5.—Weather Conditions.

Paint shall not be applied when the air temperature is below 40" P.or when the air is misty, or when, in the opinion of the engineer, conditionsare otherwise unsatisfactory for the work. It shall not be applied upondamp or frosted surfaces.

Material painted under cover in damp or cold weather shall remainunder cover until dry or until weather conditions permit its exposure in the

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open. Painting shall not be done when the metal is hot enough to cause thepaint to blister and produce a porous paint film.

2. 14. 6.—Application.

(a) General.

Painting shall be done in a neat and workmanlike manner. Paint maybe applied with hand brushes or by spraying except that aluminum paintpreferably shall be applied by spraying. By either method the coating ofpaint applied shall be smoothly and uniformly spread so that no excesspaint will collect at any point. If work done by spraying is not satisfactoryto the engineer, hand brushing will be required.

(b) Brushing.

When brushes are used, the paint shall be so manipulated under thebrush as to produce a smooth, uniform, even coating in close contact withthe metal or with previously applied paint, and shall be worked into allcorners or crevices

(c) Spraying.

Power spraying equipment shall apply the paint in a fine, even spraywithout the addition of any thinner. In cool weather, the paint may bewarmed to reduce the viscosity for use. Such warming shall be accomplished by heating the paint containers in water or by placing them onsteam radiators.

Paint when applied with spray equipment shall be immediately followed by brushing when necessary to secure uniform coverage and toeliminate wrinkling, blistering and airholes.

(d) Inaccessible Surfaces.

On all surfaces which are inaccessible for paint brushes, the paint shallbe applied by spraying or with sheepskin daubers to insure thoroughcovering.

2. 14. 7.—Removal of Paint.

If the painting is unsatisfactory to the engineer, the paint shall be

removed and the metal thoroughly cleaned and repainted.

2. 14. 8.—Thinning Paint.

Paint as delivered in containers when thoroughly mixed is ready foruse. If it is necessary in cool weather to thin the paint in order that itshall spread more freely, this shall be done only by heating in hot wateror on steam radiators, and liquid shall not be added nor removed unlesspermitted by the engineer.

2. 14. 9.—Painting Galvanized Surfaces.

Galvanized surfaces which are required to be painted shall be treatedas follows:

For the purpose of conditioning the surface of galvanized surfaces forpainting, the painting shall be deferred as long as possible in order thatthe surface may weather.

Before painting galvanized surfaces they shall be treated as follows:In 1 gallon of soft water dissolve 2 ounces each of copper chloride,

copper nitrate, and sal ammoniac, then add 2 ounces of commercial muriaticacid. This should be done in an earthen or glass vessel, never in tin orother metal receptacle. Apply the solution with a wide flat brush to the

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galvanized surface, when it will assume a dark, almost black, color, whichon drying becomes a grayish film.

2. 14. 10.—Cleaning of Surfaces.

(a) General.

Surfaces of metal to be painted shall be thoroughly cleaned, removingrust, loose mill scale, dirt, oil or grease and other foreign substances. Unlesscleaning is to be done by sand blasting, all weld areas, before cleaning isbegun, shall be neutralized with a proper chemical, after which it shall bethoroughly rinsed with water.

Three methods of cleaning are provided herein. Any of these methodsmay be used unless otherwise specified.

(b) Method A.—Hand Cleaning.The removal of rust, scale and dirt shall be done by the use of metal

brushes, scrapers, chisels, hammers or other effective means. Oil andgrease shall be removed by the use of gasoline or benzine. Bristle or woodfiber brushes shall be used for removing loose dust.

(c) Method B.—Sandblasting.

All steel shall be cleaned by sandblasting. The sandblasting shallremove all loose mill scale and other substances down to the bare metal.Special attention shall be given to cleaning of corners and re-entrant angles.Before painting, sand adhering to the steel in corners and elsewhere shallbe removed. The cleaning shall be approved by the engineer prior to anypainting. The material shall be painted before rust forms.

(d) Method C.—Flame Cleaning.

Unless otherwise provided in the supplemental specifications, all metal,except the exposure of the inside of boxed members and other surfaceswhich will be inaccessible to the flame cleaning operation after the memberis assembled, shall be flame cleaned in accordance with the followingoperations :

(1) Oil, grease and similar adherent matter shall be removed by washing with a suitable solvent. Excess solvent shall be wiped from the workbefore proceeding with subsequent operations.

(2) The surfaces to be painted shall be cleaned and dehydrated (freedof occluded moisture) by the passage of oxyacetylene flames which have anoxygen to acetylene ratio of at least one. The inner cones of these flamesshall have a ratio of length to port diameter of at least 8 and shall be notmore than 0.15 inch center to center. The oxyacetylene flames shall be

traversed over the surfaces of the steel in such manner and at such speed

that the surfaces are dehydrated; and dirt, rust, loose scale, scale in theform of blisters or scabs, and similar foreign matter are freed by therapid, intense heating by the flames. The flames shall not be traversed so

slowly that loose scale or other foreign matter is fused to the surface ofthe steel. The number, arrangement and manipulation of the flames shallbe such that all parts of the surfaces to be painted are adequately cleanedand dehydrated.

(3) Promptly after the application of the flames, the surfaces of thesteel shall be wire brushed, hand scraped wherever necessary, and thenswept and dusted to remove all free material and foreign particles Compressed air shall not be used for this operation.

(4) Paint shall be applied promptly after the steel has been cleaned andwhile the temperature of the steel is still above that of the surrounding

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atmosphere, so that there will be no recondensation of moisture on thecleaned surfaces.

( e) Surfaces Inaccessible After Assembly.

Unless otherwise provided, the exposure of the inside of boxed membersand other surfaces which will be inaccessible to the flame cleaning operationafter the member is assembled shall be cleaned by Method A, Hand Cleaning.If flame cleaning of such surfaces is required, it shall be so stated in thespecial provisions and the following will apply :

The inside surfaces of boxed members and other surfaces which willbe inaccessible to the flame cleaning operation after the member is assembled, shall be cleaned as specified in paragraphs 1 and 2, and wirebrushed but not painted before the member is boxed or assembled. Afterall fabrication of the member is completed, its inside surfaces shall behand wire brushed or hand scraped wherever necessary in order to removedirt and other foreign substances which may have accumulated after thesurfaces were originally cleaned. The outside surfaces of the membersshall then be cleaned and dehydrated, wire brushed, and hand scrapedwherever necessary. All surfaces shall then be swept and dusted to removefree material and foreign particles and the member completely painted.

2. 14. 11.—Shop Painting.

Unless otherwise specified, steelwork shall be given one coat of approvedpaint after it has been accepted by the inspector and before it is shippedfrom the plant.

Surfaces not in contact but inaccessible after assembly or erection shallbe painted three coats. The shop contact surfaces shall not be painted.Field contact surfaces shall receive a shop coat of paint, except main splicesfor chords of trusses and large girder splices involving multiple thicknessesof material where a shop coat of paint would make erection difficult.Field contact surfaces not painted with the shop coat shall be given a coatof approved lacquer or other protective coating if it is expected that therewill be a prolonged period of exposure before erection.

Surfaces which will be in contact with concrete shall not be painted.Structural steel which is to be welded shall not be painted before

welding is complete. If it is to be welded only in the fabricating shop andsubsequently erected by bolting, it shall receive one coat of paint aftershop welding is finished. Steel which is to be field welded shall be givenone coat of boiled linseed oil or other approved protective coating aftershop welding and shop fabrication is completed.

Surfaces of iron and steel castings, either milled or finished, shall be

given one coat of paint.With the exception of abutting joints and base plates, machine-finished

surfaces shall be coated as soon as practicable after being accepted, witha hot mixture of white lead and tallow or other approved coating, beforeremoval from the shop.

Erection marks for the field identification of members and weightmarks shall be painted upon surface areas previously painted with theshop coat. Material shall not be loaded for shipment until it is thoroughlydry, and in any case not less than 24 hours after the paint has been applied.

2. 14. 12.—Field Painting.

When the erection work is complete, including all riveting and straightening of bent metal, all adhering rust, scale, dirt, grease or other foreignmaterial shall be removed as specified under Cleaning of Surfaces.

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As soon as the inspector has examined and approved all field rivetsdriven, the heads of such rivets and field bolts, all welds and any surfacesfrom which the shop or first coat of paint has become worn off or hasotherwise become defective, shall be cleaned and thoroughly covered withone coat of shop-coat paint.

Surfaces to be riveted in contact and surfaces which will be in contactwith concrete shall not be painted. Surfaces which will be inaccessibleafter erection shall be painted with such field coats as are called for onplans or authorized. When the paint applied for retouching the shop coathas thoroughly dried and the field cleaning has been satisfactorily completed, such field coats as are called for on the plans or are authorized shallbe applied. In no case shall a succeeding coat be applied until the previouscoat has dried throughout the full thickness of the paint film. All smallcracks and cavities which were not sealed in a watertight manner by thefirst field coat shall be filled with a pasty mixture of red lead and linseed oilbefore the second coat is applied.

The following provision shall apply to the application of both fieldcoats. To secure a maximum coating on edges of plates or shapes, rivetheads and other parts subjected to special wear and attack, the edges shallfirst be striped with a longitudinal motion and the rivet heads with a rotarymotion of the brush, followed immediately by the general painting of thewhole surface, including the edges and rivet heads.

If, in the opinion of the engineer, traffic produces an objectionableamount of dust, the contractor shall, at his own expense, allay the dust forthe necessary distance on each side of the bridge and take any other precautions necessary to prevent dust and dirt from coming in contact withfreshly painted surfaces or with surfaces before the paint is applied.

The application of the second field coat shall be deferred until adjoiningconcrete work has been placed and finished. If concreting operations havedamaged the paint, the surface shall be recleaned and repainted.

The contractor shall protect pedestrian, vehicular and other trafficupon or underneath the bridge, and also all portions of the bridge superstructure and substructure, against damage or disfigurement by spatters,splashes and smirches of paint or paint materials.

SECTION 15—Riprap


Unless otherwise modified herein, all materials shall conform to therequirements of division IV.

2. 15. 2.—Dry Riprap, Class 1 for Slopes.

Unless otherwise specified, all stones used in this class of riprap shallweigh between 50 and 150 pounds each and at least 60 per cent of themshall weigh more than 100 pounds each.

The stones shall be placed upon a slope not steeper than the naturalangle of repose of the filling material. The stones shall be laid with closejoints. The courses shall be laid from the bottom of the bank upward, thelarger stones being placed in the lower courses. Open joints shall be filledwith spalls.

2. 15. 3.—Dry Riprap, Class 2 for Slopes.

The stones shall be placed upon a slope not steeper than the naturalangle of repose of the filling material. Stones having one broad flat surface

92 HIGHWAY BRIDGES

shall be used when possible, this surface being laid on a horizontal earthbed prepared for it and so placed as to overlap the underlying course, theintent being to secure a lapped or "shingled" surface which will shed amaximum amount of water. Fifty per cent of the mass shall be of stoneshaving a volume of 2 cubic feet or more. These stones shall be placed firstand roughly arranged in close contact. The spaces between the largerstones shall then be filled with stone of suitable size so placed as to leavethe surface evenly stepped, conforming to the contour required, and capableof shedding water to the maximum degree practically attainable.

2. 15. 4.—Mortared Riprap for Slopes.

Stone for this purpose shall, as far as practicable, be selected as to sizeand shape in order to secure fairly large, flat-surfaced stone which willlay up with a true and even surface and a minimum of voids. The stonushall be placed upon a slope not steeper than the natural angle of reposeof the slope material. Fifty per cent of the mass shall be broad flat stones,2 cubic feet or more in volume, laid with the flat surface uppermost andparallel to the slope. These stones shall be placed first and roughlyarranged in close contact, the largest stones being placed near the base ofthe slope. The spaces between the larger stones shall be filled with stonesof suitable size, leaving the surface smooth, reasonably tight and conforming to the contour required. In general, the stone shall be laid with a degreeof care that will insure for plane surfaces a maximum variation from a trueplane of not more than 1% inches in 4 feet. Warped and curved surfacesshall have the same general degree of accuracy as specified above for planesurfaces.

As each of the larger stones is placed, it shall be surrounded by freshmortar and adjacent stones shall be shoved into contact. After the largerstones are in place, all of the spaces or openings between them shall befilled with mortar and the smaller stones, then placed by shoving theminto position, forcing excess mortar to the surface and insuring that eachstone is carefully and firmly bedded laterally.

After the work has been completed as above described, all excessmortar forced up shall be spread uniformly to completely fill all surfacevoids. All surface joints shall then be roughly pointed up either withflush joints or with shallow, smooth raked joints.

2. 15. 5.—Grouted Riprap for Slopes.

Grout for grouted riprap shall consist of one part of portland cementand three parts of sand, thoroughly mixed with water to produce grouthaving a thick, creamy consistency.

The stones shall be of the same sizes and placed in the same manneras specified above for Dry Riprap, Class 1, care being taken during placingto keep earth or sand from filling the spaces between the stones. Afterthe stones are in place, the spaces. between them shall be completely filledwith grout from bottom to top, and the surface swept with a stiff broom.No riprap shall be grouted in freezing weather, and in hot, dry weatherthe work shall be protected from the sun and kept moist for at least threedays after grouting.

2. 15. 6.—Stone Riprap for Foundation Protection.

Stone riprap for pier and abutment protection shall range, in size,up to derrick stone and shall be graded from coarse to fine in such manneras to produce a minimum of voids. It shall be deposited where directed;

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stone deposited contrary to directions will be considered wasted and willnot be paid for.

2. 15. 7.—Concrete Riprap in Bags.

Concrete riprap in bags shall consist of Class "C" concrete in cementsacks or suitable burlap bags. The bags shall be about two-thirds filledwith concrete, securely tied, and immediately placed in the work. Whenused for foundation protection the bags of concrete shall be placed inaccordance with the provisions governing the placement of stone riprap forfoundation protection as specified above. When used for slope protection,riprap of this material shall be placed in conformance with the abovespecified provisions governing the placement of Dry Riprap, Class 1.

Concrete Slab Riprap

2. 15. 8.— -General.

The concrete slabs for riprap shall consist of concrete, cast in place,4 inches thick, unless otherwise specified or noted on the plans. The slabsshall be of two types, plain concrete or reinforced. If reinforcement isrequired, it shall be furnished as shown on the plans. Except as modifiedherein, construction shall conform to specifications for Concrete Masonry,division II.

2. 15. 9 Concrete.

The concrete shall be Class B unless the riprap is exposed to salt water,in which case it shall be Class A. It shall be of such consistency that itcan be placed without the use of top forms.

2. 15. 10.—Placing.

A trench of the dimensions shown on the plans or as given by theengineer shall be dug at the toe of the slope and the slope shall be dressedto the lines and grades given by the engineer.

The riprap shall be placed in blocks of dimensions as shown on theplans, alternate blocks being poured and the remaining panels filled in later.

Unless otherwise specified, the blocks shall be laid in horizontal coursesand successive courses shall break joints with preceding ones. The jointdetails shall be as shown on the plans, but if not shown the horizontal jointsshall be normal to the slope and shall be cold joints without filler. Thejoints extending up the slope shall be formed with %-inch lumber, whichshall be removed and the joint left open. The slabs shall be finished witha wood float.


Payment for riprap shall include the cost of furnishing all materialsand tools, the preparation of the subgrade, the laying and grouting of thestone and all other work incidental to finished construction in accordancewith these specifications. The basis of payment shall be as follows:

Stone riprap for slope walls shall be paid for on the basis of theactual number of square yards of material placed.

Stone riprap for foundation protection shall be paid for on the basisof volume or weight as may be specified.

Concrete riprap in bags shall be paid for on the basis of the actualnumber of cubic yards of riprap placed.

Concrete slab riprap shall be paid for on the basis of the actual number

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of square yards of riprap placed. If reinforcing is specified, it shall be

included in the contract price for concrete slab riprap.

SECTION 16—Concrete Cribbing

2. 16. 1.—General.

The construction of concrete cribbing shall consist of the furnishingand installation of reinforced concrete crib members and the placing ofthe interior filling materials. The crib members shall be cast in theproportions and in conformance with the general requirements set forthfor precast concrete bearing piles. Dowels, where used shall be of wrought-iron or galvanized steel not less than 1 inch in diameter and of the requiredlength.

Casings for dowels shall be of galvanized steel or iron pipe not lessthan 1% inches in diameter.

The details of the crib members and their arrangement shall be as

shown on the plans. If specific details for reinforcement are not shown on

the plans, or if the contractor is permitted to purchase the crib membersfrom manufacturers, he shall submit detailed specifications and plans forthe approval of the engineer, and such plans must be approved beforedelivery of the material is begun.

All members shall be free from depressions and spalled, patched, orplastered surfaces or edges, or any other defect which may impair theirstrength or durability. Cracked or otherwise defective members will be

rejected.

2. 16. 2.—Construction.

The foundation or bed for the cribbing shall be firm and shall be

approved by the engineer before any of the crib work is placed. In general,transverse concrete sill members shall be used to support the lower cribbingcourse. Crib members shall be carefully handled and erected in suchmanner as to avoid any injury due to shock or impact. Each member shallbe secured by approved interlocking details or by means of dowels passingthrough galvanized casings. Any members which become cracked or otherwise injured during erection shall be completely renewed and replaced.

The filling for the interior of the crib shall progress simultaneouslywith the erection of the cribbing, and shall be of approved material placedin layers not to exceed 12 inches in thickness and tamped or consolidatedto the satisfaction of the engineer.


Concrete cribbing will be paid for at the contract price per cubic footfor concrete cribbing complete in place. This price shall include all materials, equipment, tools, and labor incidental to the satisfactory erection ofthe cribbing, including necessary excavation. The volume to be paid forwill be the actual net volume of the concrete in the crib members as shownon the plans. The filling for the interior of the crib will be paid for at thecontract price per cubic yard for crib filling in place.

SECTION 17—Waterproofing

2. 17. 1.—General.

When specified on the plans or in the special provisions, surfaces shallbe waterproofed as specified herein.

CONSTRUCTION 95

2. 17. 2.—Materials.The bituminous material, fabric, and joint filler used for waterproofing

shall conform to the requirements specified in division IV. Sand for themortar protection course shall conform to the requirements of division IV.

2. 17. 3.—Storage of FabricThe fabric shall be stored in a dry, protected place. The rolls shall

not be stored on end.

2. 17. 4.—Preparation of Surface.All concrete surfaces which are to be waterproofed shall be reasonably

smooth, and free from projections or holes which might cause puncture ofthe membrane. The surface shall be dry, so as to prevent the formationof steam when the hot asphalt or tar is applied, and, immediately beforethe application of the waterproofing, the surface shall be thoroughly cleanedof dust and loose materials.

No waterproofing shall be done in wet weather, nor when the temperature is below 35° F., without special authorization from the engineer.Should the surface of the concrete become temporarily damp, it shall be

covered with a 2-inch layer of hot sand, which shall be allowed to remainin place from one to two hours, or long enough to produce a warm andsurface-dried condition, after which the sand shall be swept back, uncovering sufficient surface for beginning work, and the operation repeated as

the work progresses.

2. 17. 5.—Application —General.

Asphalt shall be heated to a temperature between 300° and 350° P.,and tar for hot application shall be heated to a temperature between 200°and 250° P., with frequent stirring to avoid local overheating. The heatingkettles shall be equipped with thermometers.

In all cases, the waterproofing shall begin at the low point of thesurface to be waterproofed, so that water will run over and not againstor along the laps.

The first strip of fabric shall be of half width; the second shall be

full width, lapped the full width of the first sheet; and the third and eachsucceeding strip shall be full width and lapped so that there will be twolayers of fabric at all points with laps not less than 2 inches wide. Allend laps shall be at least 12 inches.

Beginning at the low point of the surface to be waterproofed, a coatingof primer shall be applied and allowed to dry before the first coat ofasphalt is applied. The waterproofing shall then be applied as follows :

Beginning at the low point of the surface to be waterproofed, a sectionabout 20 inches wide and the full length of the surface shall be moppedwith the hot asphalt or tar, and there shall be rolled into it, immediatelyfollowing the mopping, the first strip of fabric, of half width, which shallbe carefully pressed into place so as to eliminate all air bubbles and obtainclose conformity with the surface. This strip and an adjacent section ofthe surface of a width equal to slightly more than half the width of thefabric being used shall then be mopped with hot asphalt or tar, and a fullwidth of the fabric shall be rolled into this, completely covering the firststrip, and pressed into place as before. This second strip and an adjacentsection of the concrete surface shall then be mopped with hot asphalt ortar and the third strip of fabric "shingled" on so as to lap the first stripnot less than 2 inches. This process shall be continued until the entiresurface is covered, each strip of fabric lapping at least 2 inches over the

96 HIGHWAY BRIDGES

last strip but one. The entire surface shall then be given a final moppingof hot asphalt or tar.

The completed waterproofing shall be a firmly bonded membrane com

posed of two layers of fabric and three moppings of asphalt or tar,together with a coating of primer. Under no circumstances shall one layerof fabric touch another layer at any point or touch the surface, as theremust be at least three complete moppings of asphalt or tar.

In all cases the mopping on concrete shall cover the surface so thatno gray spots appear, and on cloth it shall be sufficiently heavy to com

pletely conceal the weave. On horizontal surfaces not less than 12 gallonsof asphalt or tar shall be used for each 100 square feet of finished work,and on vertical surfaces not less than 15 gallons shall be used. The workshall be so regulated that, at the close of a day's work, all cloth that islaid shall have received the final mopping of asphalt or tar. Special careshall be taken at all laps to see that they are thoroughly sealed down.

2. 17. 6.—Application—Details.

At the edges of the membrane and at any points where it is puncturedby such appurtenances as drains or pipes, suitable provisions shall be madeto prevent water from getting between the waterproofing and the waterproofed surface.

All flashing at curbs and against girders, spandrel walls, etc., shall be

done with separate sheets lapping the main membrane not less than 12

inches. Flashing shall be closely sealed either with a metal counter-flashing or by embedding the upper edges of the flashing in a groovepoured full of joint filler.

Joints which are essentially open joints but which are not designedto provide for expansion shall first be caulked with oakum and lead wooland then filled with hot joint filler.

Expansion joints, both horizontal and vertical, shall be provided withsheet copper or lead in "U" or "V" form in accordance with the details, andafter the membrane has been placed shall be filled with hot joint filler. Themembrane shall be carried continuously across all expansion joints.

At the ends of the structure the membrane shall be carried well downon the abutments and suitable provision made for all movement.

2. 17. 7.—Damage Patching.Care shall be taken to prevent injury to the finished membrane by

the passage over it of men or wheelbarrows, or by throwing any materialon it. Any damage which may occur shall be repaired by patching.Patches shall extend at least 12 inches beyond the outermost damagedportion and the second ply shall extend at least 3 inches beyond the first.

2. 17. 8.—Protection Course.Over the waterproofing membrane, constructed as specified above, there

shall be constructed a protection course which, unless otherwise specifiedor shown on the plans, shall be a 2-inch course of mortar mixed in theproportion of one part portland cement and two parts sand. This mortarcourse shall be reinforced midway between its top and bottom surfaceswith wire netting of 6-inch mesh and No. 12 gauge, or its equivalent.The top surface shall be troweled to a smooth, hard finish and, whererequired, true to grade.

The construction of the protection course shall follow the waterproofingso closely that the latter will not be exposed without protection for morethan 24 hours.

CONSTRUCTION 97

2. 17. 9.—Measurement and Payment.Payment for waterproofing shall include the cost of furnishing all

equipment, materials and labor necessary for the satisfactory completionof the waterproofing membrane and the protection course.

Payment will be made on the basis of the number of square yards ofwaterproofing complete in place.

SECTION 18—Dampproofing

2. 18. 1.—General.

When specified on the plans or in the special provisions, surfacesshall be dampproofed as specified herein.

2. 18. 2 Materials.The material used for dampproofing shall be tar or asphalt as required

by the special provisions.Tar for absorptive treatment (or primer) and tar seal coat shall

comply with the requirements specified in division IV. Asphalt for primerand seal coat shall conform to the requirements for Asphalt, division IV.

2. 18. 3.—Preparation of Surface.

The surface to which the dampproofing coating is to be applied shallbe cleaned of all loose and foreign material and dirt and shall be dry.When necessary the engineer may require the surface to be scrubbed withwater and a stiff brush, after which the surface shall be allowed to drybefore application of the primer.

2. 18. 4.—Application.

Concrete, brick or other surfaces which are to be protected by dampproofing shall be thoroughly clean before the primer is applied. Theyshall then be brush or spray painted with two or more coats (as indicatedon the plans or in the special provisions) of tar or asphalt for absorptivetreatment. Below ground not less than two coats shall be applied, using% gallon for each square yard of surface. On the well-primed surfaceone application of tar or asphalt seal coat shall be applied by brush, usingVio gallon per square yard.

Care shall be taken to confine all paints to the areas to be waterproofed and to prevent disfigurement of any other parts of the structureby dripping or spreading of the tar or asphalt.


Payment for dampproofing shall include the cost of furnishing allequipment, materials and labor necessary for the satisfactory completionof the work.

Payment will be made on the basis of the number of square yards ofdampproofing complete in place.

SECTION 19—Name Plates

2. 19. 1.—General Requirements.

When specified, the contractor for the superstructure shall furnish andinstall name plates of such form, dimensions, material and design as maybe shown on the plans. Unless otherwise provided, the contract price forthe superstructure shall include the cost of such name plates.

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No permanent plates or markers other than those shown on the plansor approved by the engineer will be permitted on any structure.

SECTION 20— Timber Structures


(a) Lumber and Timber.

Lumber and timber shall conform to the requirements of division IV.For the various structural purposes the following grades shall be used :

Structural purpose

(1) Truss members, tensionFloor beamsStringersOther floor members

(2) CapsPosts, bridge and guard railSillsMud sillsNailing stripsTruss members, compressionTimbers (culverts)

(3) JoistDecking, wearingOther floor membersRailsRail postsNailing stripsTruss members, compression

and tensionGuard rail

(4) Wheel and felloe guards

(5) Sub-decking, flatSub-decking, laminatedBracing, sway, sasl , and

longitudinalGirtsBulkhead plankScupper blocksCleatsGrillage

Size of member

5" x 8"and

larger

Standard grade

(6) Cross-bridgingSidewalkFirestops

(7) Truss housingInside sheathing

6" x 6" andlarger

4"_ andthinner

'x 6" andlarger

4" andthinner

and 1U"thick

Il800#f, or 1600#f, or 1400#f

|structural beams and

[ stringers

1200#c or 1100#c structuralposts and timbers

1800#f, 1600ff, or 1400#fstructural joist and plank.

/ 1100#c structural posts and\ timbers

1200#f or 1100#f joist andplank

1 2" and 3" (V thick < No. 1 dimension

I D select

\ boardsfinish, or No. 1

(8- For temporary structures which are for use only during erection or for emergency use, the grades of 1200#f or llOOifc may be substituted for 1800#f,1600#f, 1400#f, or 1200)fc where specified above; No. 1 Dimension for 1200#fand llOOff, and No. 1 timbers for llOOff.

CONSTRUCTION 99

(b) Structural Shapes.Rods, plates and shapes shall be of structural steel or wrought-iron,

as specified, conforming to the requirements of division IV. Eyebars shallconform to the requirements of division IV for structural steel eyebars.

(c) Castings.Castings shall be cast steel or gray-iron, as specified, conforming to

the requirements of division IV.

(d) Hardware.Machine bolts, drift-bolts and dowels may be either wrought-iron or

medium steel. Washers may be cast O-gee or malleable castings, or theymay be cut from medium steel or wrought-iron plate, as specified.

Machine bolts shall have square heads and nuts, unless otherwise specified. Nails shall be cut or round wire of standard form. Spikes shall becut or wire spikes, or boat spikes, as specified.

Nails, spikes, bolts, dowels, washers and lag screws shall be black orgalvanized, as specified.

Unless otherwise specified, all hardware, except malleable iron connectors, for treated timber bridges, shall be galvanized or cadmium plated.

2. 20. 2 Timber Connectors.

Timber connectors shall be one of the following types, as specified onthe plans; the split ring, the toothed ring, the shear plate, the claw plateor the spike grid. The split ring and the shear plate shall be installed inprecut grooves of dimensions as given herein or as recommended by themanufacturer. The toothed ring and the spike grid shall be forced into thecontact surfaces of the timbers joined by means of pressure equipment.All connectors of this type at a joint shall be embedded simultaneously anduniformly. The claw plate shall be installed by a combination of bothmethods, partially by precut grooving and partially by pressure.

Fabrication of all connectored structures shall be done prior to treatment. When prefabricated from templates or shop details, bolt holes shallnot be more than %e inch from required placement. Bolt holes shall be Vieinch larger than bolt diameter. Bolt holes shall be bored perpendicular tothe face of the timber.

Timber after fabrication shall be stored in a manner which will prevent changes in the dimensions of the members before assembly.

Connectors for treated timber structures, except those of malleable iron,shall be galvanized in accordance with A. S. T. M. specification A-123 —47.

Connectors shall conform to the requirements of division IV, section 27.

Dimensions of material and details not otherwise specified shall meetwith the approval of the engineer.

2. 20. 3 Storage of Material.

Lumber and timber on the site of the work shall be stored in piles.

Untreated material shall be open-stacked at least 12 inches above theground surface and piled to shed water and prevent warping. When required by the engineer, it shall be protected from the weather by suitablecovering.

Creosoted timber and piling shall be close-stacked and piled to preventwarping.

The ground underneath and in the vicinity of all material piles shallbe cleared of weeds and rubbish.

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2. 20. 4.—Workmanship.Workmanship shall be first class throughout. None but competent

bridge carpenters shall be employed and all framing shall be true and

exact. Unless otherwise specified, nails and spikes shall be driven withjust sufficient force to set the heads flush with the surface of the wood.Deep hammer marks in wood surfaces shall be considered evidence of poorworkmanship and sufficient cause for removal of the workman causing them.The workmanship on all metal parts shall conform to the requirementsspecified for steel structures, division II.2. 20. 5.—Treated Timber.

(a) Handling.Treated timber shall be carefully handled without sudden dropping,

breaking of outer fibers, bruising or penetrating the surface with tools.It shall be handled with rope slings. Cant hooks, peaveys, pikes or hooksshall not be used.

(b) Framing and Boring.All cutting, framing, and boring of treated timbers shall be done before

treatment in so far as is practicable. When treated timbers are to be placedin waters infested by marine borers, untreated cuts, borings or other jointframings below high water elevation shall be avoided.

(c) Cuts and Abrasions.

All cuts in treated piles or timbers, and all abrasions, after havingbeen carefully trimmed, shall be covered with 2 applications of a mixtureof 60 per cent creosote oil and 40 per cent roofing pitch or brush coatedwith at least two applications of hot creosote oil and covered with hotroofing pitch.

(d) Bolt Holes.All bolt holes bored, after treatment, shall be treated with creosote oil

by means of an approved pressure bolt hole treater. Any unfilled holes,after being treated with creosote oil, shall be plugged with creosoted plugs.

(e) Temporary Attachment.Whenever with the approval of the engineer, forms or temporary braces

are attached to treated timber with nails or spikes, the holes shall be filledby driving galvanized nails or spikes flush with the surface or pluggingholes as required for bolt holes.

2. 20. 6.—Untreated Timber.In structures of untreated timber the following surfaces shall be

thoroughly coated with two coats of hot creosote oil before assembling:Ends, tops and all contact surfaces of sills, caps, floor beams and stringers ;

and all ends, joints, and contact surfaces of bracing and truss members.The back faces of bulkheads and all other timber which is to be in contact

with earth, metal or other timber shall be similarly treated.Bolts passing through non-resinous wood shall preferably be galvanized.

2. 20. 7.—Treatment of Pile Heads,

(a) General.

Pile heads, after cutting to receive the caps, and prior to placing thecaps, shall be treated to prevent decay.

The heads of treated timber piles shall be protected by one of the following methods, as specified on the plans. If not otherwise specified, method

B shall be used.

CONSTRUCTION 101

(b) Method A—Zinc Covering.

The sawed surface shall be covered with three applications of a mixtureof 60 per cent creosote oil and 40 per cent roofing pitch or thoroughly brushcoated with three applications of hot creosote oil and covered with hot roofingpitch. Before placing the cap, a sheet of 12 gage. (.028-inch) zinc shall be

placed on each pile head. The sheet zinc shall be of sufficient size to projectat least 4 inches outside of the pile, and it shall be bent down, neatlytrimmed and securely fastened to the faces of the pile, with large headedgalvanized roofing nails.

(c) Method B—Fabric Covering.

The heads of all piles shall be covered with alternate layers of hot pitchand loosely woven fabric similar to membrane waterproofing, using fourapplications of pitch and three layers of fabric. The cover shall measure atleast 6 inches more in dimension than the diameter of the pile and shall beneatly folded down over the pile and secured by large headed galvanizednails or by binding or serving with not less than seven complete turns of galvanized wire securely held in place by large-headed galvanized nails andstaples. The edges of the fabric projecting below the wire wrapping shallbe trimmed to present a workmanlike appearance.

The heads of untreated piles shall be given one of the following treatments, as may be specified or directed by the engineer :

(1) The sawed surface shall be thoroughly brush coated with two applications of hot creosote oil.

(2) The sawed surface shall be heavily coated with red lead paint, afterwhich it shall be covered with cotton duck, of at least 8-ounce weight, whichshall be folded down over the sides of the pile and firmly secured theretowith large-headed roofing nails. The edges of the duck shall be trimmedto give a workmanlike appearance. The duck shall then be waterproofedby being thoroughly saturated and coated with one or more applications ofred lead paint.

2. 20. 8.—Holes for Bolts, Dowels, Rods and Lag Screws.

Holes for round drift-bolts and dowels shall be bored with a bit Meinch less in diameter than the bolt or dowel to be used. The diameter ofholes for square drift-bolts or dowels shall be equal to the least dimensionof the bolt or dowel.

Holes for machine bolts shall be bored with a bit the same diameteras the bolt.

Holes for rods shall be bored with a bit Me inch greater in diameterthan the rod.

Holes for lag screws shall be bored with a bit not larger than the bodyof the screw at the base of the thread.

2. 20. 9.—Bolts and Washers.

A washer, of the size and type specified, shall be used under all boltheads and nuts which would otherwise come in contact with wood.

The nuts of all bolts shall be effectually locked after they have been

finally tightened.

2. 20. 10.—Countersinking.Countersinking shall be done wherever smooth faces are required.

Horizontal recesses formed for countersinking shall be painted with hotcreosote oil, and, after the bolt or screw is in place, shall be filled with hotpitch.

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2. 20. 11 Framing.All lumber and timber shall be accurately cut and framed to a close fit

in such manner that the joints will have even bearing over the entire contact surfaces. Mortises shall be true to size for their full depth and tenonsshall fit snugly. No shimming will be permitted in making joints, nor willopen joints be accepted.

2. 20. 12 Pile Bents.The piles shall be driven as indicated on the plans, with a variation

of the portion above the ground of not more than % inch per foot from thevertical or batter indicated, or so that the cap may be placed in its properlocation without inducing excessive stresses in the piles. Excessive manipulation of the piles will not be permitted and the contractor will be requiredto redrive or use other satisfactory methods to avoid such manipulations.No shimming on tops of piles will be permitted.

The piles for any one bent shall be carefully selected as to size, toavoid undue bending or distortion of the sway bracing. However, care shallbe exercised in the distribution of piles of varying sizes to secure uniformstrength and rigidity in the bents of any given structure.

Cut-offs shall be accurately made to insure perfect bearing between thecap and piles.

2. 20. 13.—Framed Bent:

(a) Mud SUU.Untreated timber used for mud sills shall be of heart cedar, heart

cypress, redwood, or other durable timber. Mud sills shall be firmly andevenly bedded to solid bearing and tamped in place.

(b) Concrete Pedestals.

Concrete pedestals for the support of framed bents shall be carefullyfinished so that the sills or posts will take even bearing on them. Dowelsof not less than %-inch diameter and projecting at least 6 inches abovethe tops of the pedestals, shall be set in them when they are cast, foranchoring the sills or posts.

(c) SUh.Sills shall have true and even bearing on mud sills, piles or pedestals.

They shall be drift-bolted to mud sills or piles with bolts of not less than%-inch diameter and extending into the mud sills or piles at least 6 inches.When possible, all earth shall be removed from contact with sills so thatthere will be free air circulation around them.

(d) Posts.Posts shall be fastened to pedestals with dowels of not less than %-inch

diameter, extending at least 6 inches into the posts.Posts shall be fastened to sills by one of the following methods, as indi

cated on the plans:(1) By dowels of not less than %-inch diameter, extending at least

6 inches into posts and sills.(2) By drift-bolts of not less than %-inch diameter driven diagonally

through the base of the post and extending at least 9 inches into the sill.

2. 20. 14.—Caps.Timber caps shall be placed, with ends aligned, in a manner to secure

an even and uniform bearing over the tops of the supporting posts or piles.

All caps shall be secured by drift-bolts of not less than %-inch diameter,

CONSTRUCTION 103

extending at least 9 inches into the posts or piles. The drift-bolts shall beapproximately in the center of the post or pile.

2. 20. 1S.—Bracing.The ends of bracing shall be bolted through the pile, post or cap with

a bolt of not less than %-inch diameter. Intermediate intersections shallbe bolted, or spiked with wire or boat spikes, as indicated on the plans. Inall cases spikes shall be used in addition to bolts.

2. 20. 16.—Stringers.Stringers shall be sized at bearings and shall be placed in position so

that knots near edges will be in the top portions of the stringers.Outside stringers may have butt joints with the ends cut on a taper,

but interior stringers shall be lapped to take bearing over the full widthof the floor beam or cap at each end. The lapped ends of untreated stringersshall be separated at least Vz inch for the circulation of air and shall be

securely fastened by drift-bolting where specified. When stringers are twopanels in length the joints shall be staggered.

Cross-bridging between stringers shall be neatly and accurately framedand securely toe-nailed with at least two nails in each end. All cross-bridging members shall have full bearing at each end against the sides ofstringers. Unless otherwise specified in the contract, cross-bridging shall beplaced at the center of each span.

2. 20. 17.—Plank Floors.

Plank shall be of the grade specified in division II. Unless otherwisespecified they shall be surfaced one side and one edge.

Single plank floors shall consist of a single thickness of plank supportedby stringers or joists. The planks shall be laid heart side down, withinch openings between them for seasoned material and with tight jointsfor unseasoned material. Each plank shall be securely spiked to each joist.The planks shall be carefully graded as to thickness and so laid that notwo adjacent planks shall vary in thickness by more than He inch.

Two-ply timber floors shall consist of two layers of flooring supportedon stringers or joists. The lower course shall be pressure-treated withcreosote oil. The top course may be laid either diagonal or parallel to thecenterline of roadway, as specified and each floor piece shall be securelyfastened to the lower course. Joints shall be staggered at least 3 feet.If the top flooring is placed parallel to the centerline of the roadway,special care shall be taken to securely fasten the ends of the flooring. Ateach end of the bridge these members shall be beveled.

2. 20. 18.—Laminated or Strip Floors.

The strips shall be of the grade specified in division II. The stripsshall be placed on edge, at right angles to the center line of roadway. Eachstrip shall be spiked to the preceding strip at each end and at approximately18-inch intervals with the spikes driven alternately near the top and bottomedges. The spikes shall be of sufficient length to pass through two stripsand at least half-way through the third strip.

If timber supports are used every other strip shall be toe-nailed toevery other support. The size of the spikes shall be as shown on the plans.When specified on the plans, the strips shall be securely attached to steelsupports by the use of approved galvanized metal clips. Care shall be takento have each strip vertical and tight against the preceding one, and bearingevenly on all the supports.

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2. 20. 19.—Wheel Guards and Railings.Wheel guards and railing shall be accurately framed in accordance

with the plans and erected true to line and grade.Unless otherwise specified, wheel guards shall be surfaced one side

and one edge (S1S1E) and rails and rail posts shall be surfaced on foursides (S4S).

Wheel guards shall be laid in sections not less than 12 feet long.

2. 20. 20 Trusses.Trusses, when completed, shall show no irregularities of line. Chords

shall be straight and true from end to end in horizontal projection and, invertical projection, shall show a smooth curve through panel points conforming to the correct camber. All bearing surfaces shall fit accurately.Uneven or rough cuts at the points of bearing shall be cause for rejectionof the piece containing the defect.

2. 20. 21.—Truss Housings.

The carpentry on truss housings shall be equal in all respects to thebest house carpentry. The finished appearance of the housing is consideredof primary importance and special care shall be taken to secure a highquality of workmanship and finish on this portion of the structure. Workmen wearing shoes with caulks will not be permitted on the roof.

2. 20. 22.—Erection of Housing and Railings.

Unless otherwise directed by the engineer, housing and railings shallbe built after the removal of the falsework and the adjustment of thetrusses to correct alignment and camber.

2. 20. 23.—Painting.

Rails and rail posts, untreated timber, or timber treated with preservative salts shall be painted with three coats of paint.

Parts of the structure, other than rails and rail posts, which are to be

painted, shall be designated on the plans or in the special provisions.Metal parts, except hardware, shall be given one coat of shop paint and,

after erection, two coats of field paint.

2. 20. 24.—Measurement and Payment.Payment for timber structures shall include the furnishing of ma

terials, preservative treatment, equipment, tools and labor necessary forthe erection and painting of the work in a satisfactory manner.

Lumber and timber, unless otherwise specified, shall be paid for at thecontract price per 1,000 feet board measure (M.B.M.) for material remaining in the finished structure, including the cost of all hardware. Computations of the amount of lumber and timber in the structure shall be based on

nominal sizes and the shortest commercial length which could be used. Noother allowance for waste will be made.

Metal parts, other than hardware, shall be paid for at the contractprice per pound, the weight being computed in the same manner as specifiedfor steel structures, division II.

SECTION 21 —Preservative Treatments for Timber

2. 21. 1.—General.

The kind of preservative treatment required shall be as specified inthe special provisions or as noted on the plans. The type of treatmentshall be one of the following:

CONSTRUCTION 105

Creosote oil.Creosote-coal-tar solution.Creosote-petroleum solution.Zinc chloride.Sodium fluoride-arsenate dinitrophenol solution (Wolman Salts).Chromated zinc chloride.Zinc meta-arsenite (Z.M.A.).

The preservatives specified herein are not intended to be used interchangeably, but the kind of preservative to be used shall be adopted for itssuitability to the conditions of exposure to which it will be subjected. Someof the conditions to be considered are: effect of marine borers, effect oftermites, action of exposure to water and leeching of the preservative, effectof contact with the ground, painting requirements and cleanliness requirements. Experience records for the particular exposure intended shall be

given consideration in selecting the treatment to be used.

Treatments are subject to the following limitations:

(1) Creosote-petroleum solution shall not be used for treating southernpine piles.

(2) Creosote-petroleum solution treatment shall not be used for material that will or may be exposed to attack by marine borers.

(3) Generally, salts treatment shall be used for material which has tobe painted.

(4) Wood treated with salts shall not be used where the wood is indirect contact with the ground, except where painting is required and woodtreated with salts shall not be used where it will be in contact with water.


Timber, lumber and piling shall conform to the requirements of divisionIV and shall be inspected prior to treatment. The preservatives used shallconform to the requirements of division IV.

2. 21. 3.—Preparation for Treatment.

(a) Sorting.

Whenever it is practicable the material shall be sorted into one kind ordesignated group of kinds of wood and into pieces of approximately equalsize and moisture and sapwood content, and so separated as to insure contactof the treating medium with all surfaces.

(b) Framing.

So far as practicable, all adzing, boring, chamfering, framing, gaining,mortizing, surfacing, etc., shall be done prior to treatment.

(c) Incising.

All Douglas fir lumber treated with creosote or creosote-petroleummixture, whose least dimension is 2 inches or over, shall be incised in asuitable power-driven machine. Lumber having a thickness of 3 inchesand over shall be incised on all four sides. Lumber less than 3 inches thickshall be incised on the wide faces only, except where indicated on thedrawings. The spacing and shape of the cutting teeth and the methodof incising shall be such as to produce a uniform penetration. The depth ofthe incisions shall be not less than the following :

106 HIGHWAY BRIDGES

Minimum depthSize of incision

2x123 x 124x12 y2"8x10 %

10x12 %"12x12 %"

Intermediate sizes in proportion.

2. 21. 4.—Amount of Preservative.

The net retention in any charge shall be not less than 90 per cent of thequantity of preservative that may be specified; but the average retentionby the material treated under any contract or order and the average retention of any five consecutive charges shall be at least 100 per cent of thequantity specified. Unless otherwise specified in the proposal or plans, theminimum amount of preservative retained shall be as follows:

(a) Creosote, Creosote Coal-Tar Solution or Creosote Petroleum SolutionTreatment

Min. net retentionof preservative per

Material cu. ft. of woodStructural timber (Southern pine) 10 lbs. empty cellStructural timber (Douglas Fir) 5 inches or less in thickness . . 10 lbs. empty cellStructural timber (Douglas Fir) more than 5 inches in thick

ness 8 lbs. empty cellSouthern yellow pine piles for land or fresh water use 12 lbs. empty cellDouglas Fir piles for land or fresh water use 10 lbs. empty cellSouthern yellow pine piles and timber in salt water subject to

attack by marine borers 20 lbs. full cellDouglas Fir piles in salt water subject to attack by marine

borers 14 lbs. full eel!Douglas Fir timber in salt water subject to attack by marine

borers 14 lbs. full cell

(b) Salts TreatmentsPounds dry salt per

cu. ft.Zinc chloride 1.00Sodium fluoride-arsenate-dinitrophenol solution (Wolman

Salts) .35Chromated zinc chloride .75Zinc meta-arsenite (Z.M.A.) .35

2. 21. 5.—Pressure Treatment Processes.

All lumber and piles shall be treated according to current A. W. P. A.Standard Specifications for Preservative Treatment by Pressure Processes.

When a clean treatment is desired it shall be obtained by using theoptional method provided in the treatment specifications. If required it shallbe so stated in the special provisions.

SECTION 22— Timber Cribbing

2. 22. 1.—Material,

(a) Timber.Timber used for cribbing shall conform to the requirements of divi

sion IV, and unless otherwise specified shall be the same as for caps, posts,

CONSTRUCTION 107

sills, etc. If treated timber is used all hardware shall be galvanized or cadmium plated.

(b) Logs.

Logs used for cribbing shall conform in quality to the requirementsspecified for timber piles in division IV.

2. 22. 2.—Preparation.When timber or logs are to be treated, all framing shall be completed

before treatment and all surfaces cleaned of dirt and grease.All timber and log framing shall be done in a workmanlike manner

and true to line and angle.

2. 22. 3. —Dimensions.

(a) Timber.

When cribs are constructed of sawed timber, no timber shall be lessthan 8 inches in least dimension. The face timber in the base tier shall be

not less than 10 inches in least dimension.

(b) Logs.

When cribs are constructed of logs, no face log shall have a diameterat the small end of less than 10 inches and tie logs shall be not less than8 inches in diameter at the small end. The face log in the base tier shallbe not less than 12 inches in diameter at the small end.

All logs for cribbing shall be selected from the logs available with assmall an amount of taper as possible. The length of logs used shall be.somewhat dependent upon the taper.

2. 22. 4. —Construction.

(a) Foundation.The foundation or bed for the cribbing shall be excavated to exact

grade and shall be approved as to bearing quality by the engineer before anyof the crib work is placed.

(b) Mud Sills.When mud sills are used, they shall be set at right angles to the face of

the cribbing and firmly and evenly beaded in the foundation material.Mud sills shall be not less than 12 by 12 inches in squared cross-sectional

dimensions and not less than 3 feet in length. They shall be spaced notmore than 4 feet apart.

Log or timber mud sills shall be leveled to fit the first tier resting uponthem. In no case shall there be less than 100 square inches of flat contactsurface between the face log and each mud sill.

Foundation material shall be thoroughly tamped around all mud sills.

(c) Face Logs or Timbers.

The logs or timbers in the base tier and in alternate tiers above thebase shall be as long as practicable and, preferably, shall extend the fulllength of the face. In intermediate tiers they may have a length of notless than 8 feet, arranged to break joints. Crib faces shall be laid solidor with spacers as indicated on the plans.

All framed surfaces shall receive a heavy coat of approved preservativeat the time of assembling.

Care shall be exercised in the erection of all cribs to produce a trueface as shown on the plans and all timbers or logs in faces shall be horizontal.

108 HIGHWAY BRIDGES

(d) Ties.The length of ties shall be sufficient to develop the required anchorage

against overturing, and in no case shall the length of tie extending intothe fill be less than two-thirds of the height of fill above the tie in question.

Ties shall be anchored to the face walls by framing, either dove-tailedor by sufficient projection beyond the face of the crib to form the properanchorage. Ties shall be anchored at the fill end to cross pieces fastenedto them at right angles by drift-bolts or other suitable means.

Ties shall be spaced not more than 8 feet center to center in anyhorizontal tier and shall be staggered with the next adjacent tier of ties.Tiers of ties shall be not more than 3 feet apart vertically.

(e) Fastening.Each successive tier of logs or timbers shall be drift-bolted to the one

upon which it rests by drifts not less than % inch in diameter and of sufficient length to extend through 2 tiers and not less than 4 inches into thethird tier.

Drift-bolts shall be staggered and not more than 8 feet center to centerin each tier.

All end joints and splices shall be half-lapped for 10 inches and driftedat the center.

Before assembling, all framed joints in contact shall be heavily coatedwith an approved preservative.

2. 22. 5.—Filling.Filling inside and around cribs shall be of the material specified and

shall be placed in a careful manner so as to avoid distortion of the crib.Filling shall be placed in even horizontal layers and compacted to reducethe voids to a minimum.

2. 22. 6.—Measurement and Payment.Payment for the construction of cribbing shall include the furnishing

of all materials, equipment, tools and labor necessary for the excavation,crib erection, and filling, complete in place, in accordance with the plans andthese specifications. Payment for timber and logs shall include the costof drift-bolts and other miscellaneous hardware.

Excavation for cribbing shall be paid for at the contract price percubic yard for material actually removed except that in no case shall thisbe computed to include material more than 1 foot outside of vertical planesthrough the extreme neat lines of the finished crib or its supports. Thecontract price for excavation shall include a yardage of back-fill equivalentto that excavated.

Timber shall be paid for at the contract price per 1,000 feet boardmeasure (M.B.M.) for material remaining in the finished structure.

Logs shall be paid for at the contract price per linear foot, for each size

specified, for material remaining in the finished structure.Filling material shall be paid for at the contract price per cubic yard

for the actual volume placed.

SECTION 23 —Sectional Plate Pipe and Arches


This item shall consist of furnishing sectional plate pipe or archesconforming to these specifications and of the sizes and dimensions required

on the plans and installing such pipe or arches at such places as are

CONSTRUCTION 109

designated on the plans or by the engineer, and in conformity with thelines and grades established by the engineer.

2. 23. 2.—Materials.The materials shall be as specified in division IV.

2. 23. 3.—Description of Plates.Plates shall consist of structural units of galvanized corrugated metal.

Standard plates shall have a covering width of not less than 47 inches,measured along the neutral axis of the plate, and shall be available innominal lengths of 10 feet, 7% feet, 5 feet, and 2% feet. (Plates have approximately a 2-inch lip beyond each end crest, which results in the actuallength of a given structure being approximately 4 inches longer than thenominal length, except when skewed or beveled. In constructing footingsfor arches, this additional length must be provided for.)

The gage of plates and the radius of curvature shall be as specified indivision III or as shown on the plans.

The plates at longitudinal and circumferential seams shall be connectedby bolts. Circumferential seams shall be staggered, so that no circumferential seam shall be continuous for a greater distance than the width ofthe plates.

2. 23. 4.—Forming and Punching Plates.

Each plate shall be curved to the proper radius, and the bolt holesshall be so punched that all except end plates shall be interchangeable inthe erection process. As an alternate to this punching, the plates used inthe two bottom segments of the arch shall be punched with one row of boltholes adjacent to the longitudinal edge of the plate which is to rest uponthe pier or abutment.

Unless otherwise specified, bolt holes along those edges of the plates thatwill form longitudinal seams in the finished structure shall be staggered inrows 2 inches apart, with one row in the valley and one in the crest of thecorrugations.

Bolt holes along those edges of the plates that will form circumferential seams in the finished structure shall provide for a bolt spacing of approximately 12 inches.

The center of no hole shall be closer to the edge of the plate than 1%times the diameter of the bolt.

Bolt holes in plates 7 to 1 gage, inclusive, shall be punched before platesare galvanized.

When the completed structure is to be a full circle pipe, the plates shallbe so curved that when bolted together, true circles shall be formed of therequired diameter. The diameter of the pipe, in inches, divided by 15, shalldetermine the number of plates required to make a full circle, unless otherwise shown on the plans.

Plates for forming skewed or sloped ends shall be cut so as to give theangle of skew or slope specified. Burnt edges shall be free from oxide andburrs, shall present a workmanlike finish, and legible identification numeralsshall be placed on each part plate to designate its proper position in thefinished structure.

2. 23. 5.—Field Erection—Pipe Structures.

Excavation shall be made as provided in section 1 under Excavationand Fill and as modified hereafter.

When a pipe structure is to be erected in a trench, the width of the

110 HIGHWAY BRIDGES

trench must be sufficient to permit thorough tamping of the earth backfillagainst every plate except the bottom one.

Bedding. The pipe shall be bedded in an earth foundation of uniformdensity carefully shaped, by means of a template supported at the desiredgrade, to fit the lower plate of the pipe. Where rock in either ledge orboulder formation is encountered it shall be removed below grade and replaced with suitable materials in such manner as to provide a compactedearth cushion having a thickness under the pipe of not less than V2 inchper foot height of fill over the top of the pipe, with a minimum allowablethickness of 8 inches. Where a firm foundation is not encountered, at thegrade established, due to soft, spongy or other unstable soil, unless otherspecial construction methods are called for on the plans or in special provisions, all of such unstable soil, under the pipe and for a width of at leastone diameter on each side of the pipe, shall be removed and replaced withgravel or other suitable material properly compacted to provide adequatesupport for the pipe line.

Selected material of a gravelly nature, free from all material whichwill not pass a 3-inch circular ring shall be used in the back-filling operation. The 3-inch size limitation shall not apply to fill over one diameterabove the pipe. Backfilling material shall also be free from vegetablematter, frozen lumps and all other objectionable substances. Allowance ofa minimum camber of 1 per cent of the length of pipe shall be made to takecare of settlement after placing the fill. The amount of camber shall be

varied to suit the height of fill and supporting soil.

After the pipe has been assembled, fill material shall be deposited evenlyon both sides of the pipe, in not to exceed 6-inch layers, until at least the

34 point has been reached. Special care shall be taken to thoroughly tampthe backfilling material between the pipe and the sides of the trench or, fora distance each side of the pipe equal to the diameter of the pipe. Abovethe 94 point, the fill shall be placed uniformly on each side of the pipe inlayers not to exceed 12 inches until a height is reached equal to the diameterof the pipe, after which the remainder of the fill may be made from one

direction, but only under the supervision of the engineer.

When strutting is specified, the pipe shall be strutted as provided inarticle 2. 23. 7. The bottom row of plates shall be lapped so that theexposed edges will face downstream.

2. 23. 6.—Field Erection—Arches.

When backfilling arches before headwalls are placed, the first materialshall be placed midway between the ends of the arch forming as narrow a

ramp as possible until the top of the arch is reached. The ramp shall be

built evenly from both sides, and the backfilling material shall be thoroughlycompacted as it is placed. After the two ramps have been built to the topof the arch, the remainder of the backfill shall be deposited from the top ofthe arch both ways from the center to the ends, and as evenly as possible

on both sides of the arch.

If the headwalls are built before the arch is backfilled, the fillingmaterial shall first be placed adjacent to one headwall, until the top of the

arch is reached, after which the fill shall be dumped from the top of the arch

toward the other headwall, with care being taken to deposit the materialevenly on both sides of the arch.

In multiple installations the procedure above specified shall be followed,

CONSTRUCTION 111

but extreme care shall be used to bring the backfill up evenly on each sideof each arch so that unequal pressure will be avoided.

In all cases the filling material shall be thoroughly but not excessivelytamped. Puddling the backfill will not be permitted.

2. 23. 7 Strutting.Unless otherwise specified, sectional plate pipes shall be timber strutted

vertically 3 per cent out of round before placement of the fill. The timberstruts shall be in accordance with table 1 which follows unless an elongationother than 3 per cent is specified.

The pipe shall be deformed the required amount by means of suitablejacks. The method of jacking shall meet with the approval of the engineer. A. tolerance of % per cent above and below the specified amount willbe permitted.

Strutting shall be carried uniformly from end to end of pipe for pipeswithout headwalls. When headwalls are used there shall be no elongation ofthe ends of the pipe. The struts shall be left in place until the fill iscomplete and compacted, unless otherwise instructed by the engineer.

2. 23. 8.—Arch Substructures and Headwalls.

Substructures and headwalls shall be designed in accordance with therequirements of division III.

Each side of the arch shall be anchored to the foundation by meansof a galvanized formed channel or galvanized structural steel angle. Thearch plates shall bear directly on the channel or angle.

Channels shall be made of 7-gage material not less than inchesin depth with the shorter flange not less than 2 inches and the longer flangenot less than 4% inches. The 4% -inch flange shall be bolted to the bottomrow of plates on not to exceed 18-inch centers. Anchors shall be attachedto the web of channel on approximately 18-inch centers.

If angles are used, they shall be not lighter than 3 inches by 3 inchesby inch, and the vertical leg shall be bolted to the bottom row of plateson not to exceed 18-inch centers. Angles shall be anchored to the foundation by %-inch bolts, not less than 8 inches in length, on not to exceed24-inch centers.

2. 23. 9.—Workmanship.

It is the essence of these specifications that in addition to compliancewith the details of construction the completed pipe shall show careful,finished workmanship in all particulars. Culvert pipe on which the speltercoating has been bruised or broken either in the shop or in shipping, orwhich shows defective workmanship, shall be rejected. The requirementapplies not only to the individual plates but to the shipment on any contract as a whole. Among others, the following defects are specified asconstituting poor workmanship and the presence of any or all of themin any individual culvert plate or in general in any shipment shall constitute sufficient cause for rejection:

1. Uneven laps.2. Elliptical shaping (unless specified).3. Variation from a straight center line.4. Ragged edges.5. Loose, unevenly lined or spaced bolts.6. Illegible brand.7. Bruised, scaled, or broken spelter coating.8. Dents or bends in the metal itself.

112 HIGHWAY BRIDGES

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CONSTRUCTION 113

2. 23. 10.—Method of Measurement.

The footage to be paid for shall be the actual number of linear feetof the pipe or arch, installed in place, completed and accepted. Themeasurement shall be as follows:

Pipes and arches with square and vertical ends, end to end of metal,on center line of structure.

Pipes with skewed and vertical ends, end to end, on center line.Pipes with square ends, beveled, average end to end at top and bottom

of pipe.Pipes with skewed ends, beveled, average end to end at top and bottom

of pipe, parallel to center line.Arches, with ends other than square and vertical, as noted on the plans.

2. 23. 11.—Basis of Payment.The footages, determined as above, shall be paid for at the contract unit

prices per linear foot bid for Sectional Plate Pipe or Arches of the severalsizes, as the case may be, which prices and payments shall constitute fullcompensation for furnishing, handling, erecting and installing the pipe orarches, and for all materials, labor, equipment, tools and incidentals, neces

sary to complete this item, but shall not constitute payment for concrete ormasonry headwalls and foundations or for excavation.

SECTION 24— Wearing Surfaces

Separate Concrete Wearing Surface2. 24. 1. —Description.

Separate concrete wearing surface shall consist of a concrete pavementplaced over other deck construction. It shall conform to details shown onthe plans. The concrete may be with or without reinforcement.

« The construction shall conform to that specified for Concrete Masonry,division II.

2. 24. 2.—Measurement and Payment.Payment for separate concrete wearing surface shall include the cost

of furnishing all materials, equipment, tools and labor necessary for thecompletion of the work. Unless otherwise specified, separately placed concrete wearing surfaces will be paid for on the basis of the number of squareyards of wearing surface complete in place.

Brick Wearing Surface


Brick wearing surfaces for concrete floors shall be placed only afterthe concrete floor has been thoroughly cured.

2. 24. 4.—MaterialsAll materials used in the construction of brick wearing surfaces shall

conform to the requirements of division IV. Sand for the sand-cementbedding course shall conform to the requirements for Sand for Mortar.

2. 24. 5.—Preparation of Subfloor.After the concrete slab has been properly cured, and immediately

before the bedding course is placed, the surface of the slab shall be

thoroughly hand-broomed with stiff wire or fiber brooms to remove all dustand loose or foreign materials adhering to the surface.

114 HIGHWAY BRIDGES

2. 24. 6 Sand-Cement Bed.

The sand-cement bedding course shall consist of sand and portlandcement, in the proportion of one part cement and four parts sand, mixeddry until the mass is of a uniform color. The mixing may be done in anapproved batch mixer or by hand on a clean, tight surface.

Immediately prior to placing the sand-cement bed, the surface of thefloor slab shall be dampened thoroughly. No more of the sand-cementbed shall be mixed or prepared than can be used within any continuousworking period, and any bed upon which the bricks are not laid and rolledduring any continuous working period shall be removed and replaced withnew materials when the work is resumed.

2. 24. 7.—Placing Bedding Course.

Upon the prepared floor slab, the bedding course shall be placed andshaped so that its finished depth shall be not less than % inch and notmore than 1 inch.

The bedding shall be shaped to a true surface parallel with the surfaceof the finished roadway by means of a template extending the entire widthof the roadway, drawn forward upon the curbs or other guide rails. Whenthe width of the roadway precludes the use of a template spanning theentire distance, the bedding shall be shaped in sections, using scantlingsadjusted to correct elevations as guides. The bedding course shall be

struck off at least twice with the template. Any irregularities discoveredshall be corrected and the bed struck off with the template to its correctelevation and contour. This operation shall be continued until perfectalignment is secured.

If directed by the engineer, in addition to shaping with a templatethe bedding course shall also be compacted with a hand roller. The beddingcourse shall be alternately struck off and rolled until perfect alignmentis secured. The roller shall be not less than 36 inches in diameter and 24

inches in width, and shall weigh not less than 10 pounds per inch of width.When the use of the template and guiderails is impracticable in finish

ing the bedding course, it shall be shaped to the surface required bymeans of hand lutes.

After final shaping, the bedding shall not be disturbed prior to layingthe brick.

2. 24. 8.—Laying the Brick.

Upon the bedding course as prepared, the brick shall be laid in successive courses with the better face or wire-cut side upward. They shallbe laid with the ends and sides in contact and lugs, if any, shall be turnedin one direction. Alternate courses of brick shall begin with one-half a

brick. Each course shall be completed by batting in at the end, if necessary, with fragments of brick at least 3 inches long, a portion of the nextadjoining brick being broken off if necessary to give the minimum 3-inchbat at the end of the course. The fractured end of cut or trimmed brickshall be turned toward the center of the roadway. Every course of brickshall be laid true and even and, except in special cases, perpendicular tothe curb line. No course shall deviate from a straight line more than2 inches in 30 feet. All brick laying shall take place over brick alreadylaid and shall follow the completion of the bedding within 50 feet.

Immediately after laying the brick, the surface of the roadway shallbe swept and inspected. Any inferior brick shall be lifted out and turnedover, or removed and replaced by acceptable brick.

CONSTRUCTION 116

2. 24. 9.—Rolling the Brick.Following the inspection and after the replacement of defective brick,

the surface shall be swept free of spalls and shall then be rolled by aself-propelled tandem roller weighing approximately 3 tons. The rollingshall be done as soon as possible after laying the brick so that it may becompleted before the bed has begun to set.

Rolling shall begin at the edge of the pavement, proceeding back andforth parallel to the sides until the center of the pavement is reached.The roller shall then pass to the other edge and repeat the operation tothe center. The rolling may then be done obliquely entirely across thepavement, after which the operation shall be repeated in the oppositedirection. Broken or otherwise injured brick shall be removed and replacedbefore final rolling takes place. Final rolling shall be parallel with thecenterline of the roadway. Portions of the surface not accessible tomechanical rolling shall be hand tamped.

2. 24. 10.—Testing the Surface.After final rolling, the pavement shall be tested with a template laid

transversely and a 10-foot straight edge, laid parallel with the side of thepavement, and any unevenness exceeding % inch shall be corrected and,if necessary, the entire surrounding surface again rolled.

2. 24. 11.—Applying Asphalt Filler.All joints shall be filled with hot asphalt filler and a surface dressing

applied on the day of laying the brick.Immediately before filling the joints, the surface of the brick shall be

swept clean and the brick shall be clean and dry when filler is applied.Filler shall not be applied if the bricks are wet, nor if air temperaturesare such that the filler will not flow freely into the joints.

The filler shall be heated to a temperature between 177* C. (350° F.)and 200° C. (392° F.). All filler heated beyond 232" C. (450° F.) shallbe rejected. The heater shall be so designed as to admit of an even heatingof the entire mass, with an efficient and positive control of the heat atall times, and shall be equipped with accurate thermometers capable ofregistering at all times the temperature of the filler.

The filler shall be removed from the heater and promptly applied tothe pavement before cooling. It shall be worked into the joints by meansof hot iron squeegees operated slowly backward and forward at an anglewith the joints. Squeegee irons shall be kept hot and squeegeeing shallcontinue until the joints appear full and a thin coating of asphalt remainsupon the surface of the brick.

2. 24. 12.—Surface Dressing.Immediately after the joints have been filled, and while the filler is

still soft and pliable, the pavement shall be covered with a thin layer ofdry sand, stone or slag screenings, or granulated slag. This top dressingshall be of such sizes that all will pass a 14 -inch sieve. As soon as thedressing is spread, the surface of the pavement shall be rolled thoroughlyto bed the dressing in the asphalt coating.

2. 24. 13.—Opening to Traffic.Traffic shall not be permitted on the pavement until the filler has

cooled to air temperature.

2. 24. 14.—Measurement and Payment.Payment for brick wearing surfaces shall include the cost of furnishing

116 HIGHWAY BRIDGES

all materials, equipment, tools and labor necessary for the satisfactorycompletion of the work. Payment will be made on the basis of the numberof square yards of wearing surface complete in place.

Asphalt Block Wearing Surface

2. 24. 15.—General Requirement.

Asphalt block wearing surfaces for concrete floors shall be placed onlyafter the concrete floor has been thoroughly cured.


All materials used in the construction of asphalt block wearing surfacesshall conform to the requirements of division IV. Sand for the mortarbed shall conform to the requirements for Sand for Mortar.

2. 24. 17.—Preparation of Sub floor.After the concrete floor slab has been properly cured, and immediately

before the mortar bed is placed, the surface of the slab shall be thoroughlyhand-broomed with stiff wire or fibre brooms to remove all dust or foreignmaterial adhering to the surface.

2. 24. 18.—Mortar Bed.

The mortar bed shall consist of sand and portland cement, in theproportion of one part cement to four parts sand, mixed with sufficientwater to thoroughly moisten the ingredients and to make a mortar of suchconsistency that it can easily be spread upon the foundation and struckwith a template to a smooth and even surface. It must not, however, be sosoft as to allow the blocks to sink into the mortar when they are placedthereon.

The mortar bed shall be spread on the foundation slab and evenlydistributed in a uniform layer % inch in thickness. The bed shall be struckto a true surface exactly parallel to the top of the finished pavement infollowing manner :

Wooden strips 4 inches wide by % inch thick, or strips of steel 4 incheswide by % to inch thick, of a convenient length for handling, shallbe carefully set from curb to curb to the exact crown of the pavement andembedded throughout their length in the mortar, so that the top surfaceof the strips shall be below the grade of the finished pavement by anamount equal to the thickness of the blocks and not less, on the average,than % inch above the concrete. An iron-shod straight edge or strikershall be drawn on two sets of these strips, set as above described, to strikethe mortar bed to a true and even surface. Fresh mortar shall be addedand struck off as many times as may be found necessary to produce auniformly dense bed, free from depressions or porous spots. Special careshall be exercised to produce a bed of uniform density. As soon as themortar bed has been struck off, one set of strips shall be taken up and thetrench carefully filled with mortar so that it will have the same heightand density as the adjacent mortar.

In the case of car tracks, a template to run on the rails shall be usedto strike the mortar bed to the required grade between the rails.

2. 24. 19.—Laying the Blocks.

Upon the mortar cushion prepared as described above, the blocks shallbe immediately laid with close joints and uniform top surface.

The blocks shall be laid by the pavers standing upon the blocks alreadylaid and not upon the bed of mortar, and shall be laid at right angles to

CONSTRUCTION 117

the axis of the pavement with such crown as is shown on the plans, andin such a manner that all longitudinal joints shall be broken by a lap ofapproximately 4 inches. The blocks shall be laid so as to make the lateraljoints as tight as possible, consistent with keeping a good alignment acrossthe pavement, and where possible the longitudinal joints shall be immediately closed by pressing each course in the direction of its length with alever.

After the blocks are laid, any irregularities in the surface of the pavement shall be corrected and the pavement immediately covered with clean,dry sand, all of which shall pass a 10-mesh sieve. The sand shall be spreadover the surface and swept into the joints and shall be allowed to remainon the pavement not less than 30 days, or until such time as the actionof the traffic on the pavement shall have thoroughly ground the sand intoall the joints.

The requirements for irregularities shall be the same as for brick asgiven in article 2. 24. 10.

2. 24. 20.—Opening to Traffic.After the pavement is laid and sanded it shall be protected from all

vehicle traffic for a period of at least 7 days and for a longer period ifdirected by the engineer.

2. 24. 21. —Measurement and Payment.Payment for asphalt block wearing surfaces shall include the cost

of furnishing all materials, equipment, tools and labor necessary for thesatisfactory completion of the work. Payment will be made on the basisof the number of square yards of wearing surface complete in place.

Bituminous Carpets

2. 24. 22.—General.No mix shall be laid when, in the opinion of the engineer, climatic

conditions are not satisfactory.


The bituminous materials used in the construction of bituminous carpets shall conform to the requirements of division IV.

The aggregate shall consist of gravel, crushed stone or crushed slag,which shall be clean, sound and hard, and thoroughly dry when applied.Material containing soft or partially disintegrated particles of stone or shalewill not be accepted. The aggregate shall be washed and screened to suchsize that all of it will pass a sieve having %-inch square openings, andnot more than 15 per cent shall pass a %-inch sieve.

2. 24. 24.—Preparation of Subfloor.

(a) Wood Subfloor.Before placing the carpet coat, all parts of the subfloor shall be securely

fastened to prevent vibration and, unless otherwise specified, all sharpcorners, projections or irregularities in the surface shall be removed. Woodwhich is worn or which contains defects which may be injurious to thebituminous carpet shall be removed and replaced with new material. Anyopenings in the floor shall be completely sealed by caulking with oakum,or by other suitable means. All dust, dirt, debris or foreign material onthe surface to be treated shall be removed by sweeping with stiff broomsand if necessary the surface may be flushed with water. If water is used,

118 HIGHWAY BRIDGES

the subfloor shall be allowed to become thoroughly dry and then swept withstiff brooms before applying the first coat.

(b) Concrete Subfloor.The requirements as to cleanliness, as specified above for wood sub-

floors, shall also apply to concrete subfloors. Irregularities in the surfacesuch as might project into or injure the bituminous carpet shall be removed.Immediately before applying the first coat the surface shall be swept cleanand no traffic permitted thereon until the carpet coat is placed.

2. 24. 25.—Construction of Tar Mat Surface.

(a) Prime Coat.After the subfloor has been prepared as hereinbefore specified and is

thoroughly dry, the entire surface shall be covered with a first coat of thetar specified in division IV for Tar for First or Prime Coat. The tar shallbe applied cold at the rate of M gallon per square yard. No traffic shallbe permitted to use the surface thus treated. The prime coat shall remainin place 12 hours before applying the second coat.

(b) Second Coat.The tar used for the second coat shall be that specified in division IV

for this purpose.The tar shall be heated in an open tank or kettle to a temperature

between 200" and 225° F. and applied evenly to the surface at the rate of% gallon per square yard. The methods and appliances used shall be suchas to insure a uniform distribution of the tar over the surface of the roadway. A suitable pressure spraying device, preferably, shall be employed.Immediately after the tar is sprayed or otherwise deposited upon the roadway surface, it shall be smoothed out to a uniform thickness by means ofsqueegees, mops or other suitable spreading device. Care shall be takennot to overheat the material, the proper temperature being obtained whenit will flow with reasonable freedom and remain fluid for a sufficient periodto permit the aggregate to become thoroughly incorporated in the mass.

Immediately after the application of this coat of tar the surface shallbe covered with the aggregate at the rate of approximately 0.4 cubic footper square yard. Accurate measuring or weighing devices shall be providedby the contractor to insure the proper quantity of aggregate being used.The aggregate shall be spread evenly over the surface by means of square-pointed shovels. As soon thereafter as practicable the surface shall be

hand tamped or rolled with a heavy hand roller.After rolling or tamping is completed, if successive applications of

the tar and aggregate are necessary to obtain the required thickness theyshall be applied in the same proportions and in the same manner as specifiedfor the first application. The entire surface shall then be rolled or handtamped as specified above.

Care shall be exercised to secure a smooth, even surface, free fromdepressions or irregularities, which when tested with a 10-foot straight-edgeshall not vary by more than % inch from the specified surface contour.

The total thickness of the tar mat coat shall be as specified but in nocase shall exceed % inch.

(c) Seal Coat.If a seal coat is required by the special provisions, or by the notes on

the plans, it shall be constructed as follows:Immediately after the second coat has been completed, it shall be given

a seal coat using tar of the same grade as that specified for the second coat.

CONSTRUCTION 119

The tar shall be heated to a temperature not in excess of 225° F., dependingupon the grade used, and shall be applied at the rate of M gallon per squareyard. The seal coat shall be immediately covered with a light dressingof clean dry sand, stone screenings or granulated slag.

2. 24. 26.—Construction of Asphalt Mat Surface (Mixed Method).(a) Prime Coat.

After the subfloor has been prepared as hereinbefore specified and isthoroughly dry, the entire surface to be covered with the mat shall be givena first or prime coat of asphalt of the type and grade set forth in article4. 22. 4. For application, these asphalts may be heated to a temperatureof not more than 120° F. and shall be applied to the floor surface at therate of from 0.15 to 0.25 gallon per square yard, depending upon thecondition of the surface. Caution shall be used in heating the asphalts tothe temperature of application. The treated surface shall be allowed tocure until it becomes tacky before applying the second coat. No traffic shallbe allowed on the primed surface.

(b) Second Coat.The asphalt used shall be as set forth in article 4. 22. 4. If asphalts

type RC are used, they shall be cautiously heated to a temperature between150" F. and 275° F. If it is deemed necessary to dry the aggregate usedwith asphalts type RC, it shall be heated to a temperature of 250° F. to300° F. and its temperature when mixed with the asphalt shall not begreater than 275° F. Asphaltic emulsions shall not be heated and, normally, the aggregates used with them need not be heated.

The asphalt and aggregate, prepared as hereinbefore specified, shallbe thoroughly mixed either by hand or with a machine (preferably the

latter) until all particles of aggregate are covered with the bitumen. Ifhand mixing is done, the contractor shall provide a suitable platform formixing. Concrete mixers are acceptable for machine mixing. The proportion of the asphalt and the aggregate shall be such that the finished mixcontains from 5 per cent to 10 per cent by weight of bitumen. Accurateweighing and measuring devices shall be provided to insure that the properquantities of, materials are being used.

The mixture shall then be spread on the surface to produce the required cross section when compacted. Preferably the upper surface of themat shall be crowned to provide transverse drainage. The entire surfaceof the mat shall then be rolled with either a heavy hand roller or a lightmechanical roller. The rolling shall be done longitudinally and from theedge to the center of the mat. For side support of the mat, it is preferableto use continuous retainer strips. The thickness shall be as noted on theplans or as specified in the supplemental specifications, but the total thickness shall not be less than 94 inch nor more than 2 inches.

The finished surface shall be smooth, free of depressions or irregularities, and when tested with a 10-foot straightedge placed parallel to thecenter line of the roadway it shall not be more than % inch distant fromthe working face of such straightedge.

(c) Seal Coat.Unless otherwise provided, a seal coat shall be applied over the entire

surface of the second coat. The seal coat shall not be applied until thesecond coat has cured sufficiently. This is indicated by the absence in themat of a noticeable odor of gasoline in the case of RC materials and bythe sufficient evaporation of water to complete the breaking down of theemulsion in the case of emulsified asphalts.

120 HIGHWAY BRIDGES

The seal coat shall consist of EC asphalts preferably of the heaviergrades. The asphalts may be heated to a temperature not exceeding 275° F.,depending upon the grade of asphalt used, and shall be applied at the rateof M gallon per square yard. Caution shall be used in heating the asphaltsto the temperature of application. Immediately after application of theasphalt to the surface, a light coating of coarse dry sand, stone screeningsor granulated slag shall be uniformly applied in sufficient quantity to blotthe excess asphalt.

2. 24. 27.—-Construction of Asphalt Mat Surface (Penetration Method).(a) Prime Coat.

The first or prime coat of asphalt shall be prepared and applied in thesame manner as specified in article 2. 24. 26 for the prime coat for a MixedAsphalt Mat.

(b) Second Coat.The asphalt used shall be of the type specified in article 4. 22. 4.

After the first or prime coat has set sufficiently to become sticky, thesurface to be treated shall be covered with a thin layer of the aggregateapplied over the surface by means of square-pointed shovels. For sidesupport of the mat, it is preferable to use continuous retainer strips.

When asphaltic emulsion is used it shall not be heated. The asphaltshall be applied over the surface covered with the aggregate at the rate ofapproximately % gallon per square yard. The methods and appliancesused for the application of the asphalt shall be such as to insure a uniformdistribution of the asphalt over the surface of the roadway. Preferably, apressure spraying device shall be employed. Care shall be taken to applythe asphalt in such a way that thorough penetration of the aggregate isobtained.

If successive application of aggregate and asphalt are necessary to

obtain the required thickness, they shall be applied immediately followingthe first application. Each application shall consist of a layer of aggregate applied in the manner specified above and an application of asphaltat the rate of *4 to % gallon per square yard. The thickness shall be as

noted on the plans or as specified in the special provisions, but the totalthickness shall not be less than 94 inch nor more than 2 inches.

Over the final coat of asphalt there shall be spread a layer of dry stonescreenings, coarse sand or granulated slag sufficiently thick to preventbleeding, and the entire surface shall then be rolled with a heavy handroller or a light mechanical roller. The finished surface shall conform tothe required cross section and, preferably, shall have sufficient crown toprovide transverse drainage.

The finished surface shall be smooth, free of depressions or irregularities and when tested with a 10-foot straightedge placed parallel to thecenter line of the roadway it shall not be more than Vi inch distant fromthe working face of such straightedge.

2. 24. 28.—Opening to Traffic.No traffic shall be allowed on the bituminous mat surface for a period

of 24 hours after it has been completed. Tar and mixed asphalt mats shallnot be considered as completed until after the application of the seal coat.


Payment for bituminous carpets shall include the cost of furnishingall materials, equipment, tools and labor necessary for the satisfactorycompletion of the work. Payment will be made on the basis of the numberof square yards of bituminous carpet complete in place.

DIVISION III

DesignDesign Analysis.

In any case where the specifications provide for an empirical formulaas a design convenience, a rational analysis based on a theory accepted by

the Bridge Committee of the American Association of State HighwayOfficials, with stresses in accordance with the specifications will be considered as compliance with the specifications.

SECTION I—General Features of Design

3. 1. 1.—Determination of Waterway Area.

For the determination of the waterway area to be provided by anydrainage structure, a careful study shall be made of local conditions, including flood height, flow and frequency, size and performance of otheropenings in the vicinity carrying the same stream, characteristics of thechannel and of the watershed area, climatic conditions, available rainfallrecords and any other information pertinent to the problem and likely toaffect the safety or economy of the structure.

For culverts and small bridges, waterway formulas or drainage tablesmay be used to assist in fixing the proper size of opening. The use of suchformulas or tables is justified only to the extent that they are known tofit local conditions. However, their use shall serve merely as a guide andshall not obviate the need for careful field observation and the exercise ofintelligent judgment.

In general, the waterway provided shall be sufficient to insure the discharge of flood waters without undue backwater head and at a velocity whichwill not increase the erosive action of the stream to such an extent as toendanger the structure.

3. 1. 2.—Restricted Waterways.

When it is necessary to restrict the waterway to such an extent thatthe stream will be discharged at erosive velocities, protection against damage due to scour shall be afforded by deep foundations, curtain or cut-offwalls, riprap, stream bed paving, bearing piles, sheet piles, or other suitablemeans. Likewise, embankment slopes adjacent to all structures subjectto erosion shall be adequately protected by riprap, brush mattresses, treeretards, wing dams, or other suitable construction.

3. 1. 3.—Channel Openings.

The channel openings shall, in general, conform in width, height andlocation to all Federal, State and local requirements. Particular attention is directed to the Federal laws governing the bridging of navigablewaters and to the fact that the U. S. War Department exercises controlover all the navigable waters of the United States.

In general the clear width of all openings and the clear vertical distance between the superstructure and the highest flood water of which thereare records or other authentic evidences shall be sufficient for the passage,without damage to the structure, of ice floes and the largest drift or debriswhich may be expected.

3. 1. 4.—Pier Spacing and Location.

Piers shall be located in such manner as to meet the above specifiedrequirements for channel openings. They shall be located so as to afford

121

122 HIGHWAY BRIDGES

the minimum restriction of the waterway, especially in the main streamchannel. In general, piers shall be placed as nearly parallel with thedirection of the stream current as is practicable, due consideration beinggiven to the velocity and direction of current at both ordinary and high-water stages, so as to avoid such deflections of the current as might provedestructive to the foundations of the structure or to the adjacent streambanks.

3. 1. 5—Size of Culvert Openings.

In general, culverts shall be proportioned to carry the maximum flooddischarge without head. If the maximum flood discharge occurs only atrare intervals, culverts may be designed to carry it under slight head, provided they are protected against undermining by means of adequate pavement and apron or cut-off walls and that adjacent embankments are protected from erosion by riprap or other suitable means.

3. 1. 6.—Length of Culverts.

The length of culverts shall be sufficient to provide the full requiredwidth of roadway or the required width of embankment at the top. Theassumed slope of the embankment shall be suitable for the particular fillingmaterial and shall be such as to eliminate any tendency for the embankmentslopes to slip or slide.

3. 1. 7.—Width of Roadway and Sidewalk.

The width of roadway shall be the clear width measured at right anglesto the longitudinal center line of the bridge between the bottoms of curbsor guard-timbers, or, in the case of multiple height curbs, between the bottoms of the lower risers.

The width of the sidewalk shall be the clear width, measured at rightangles to the longitudinal center line of the bridge, from the extreme insideportion of the handrail to top of the face of the curb or guard timber, exceptthat if there is a truss, girder, or parapet wall adjacent to the roadwaycurb, the width shall be measured to its extreme walk .side portion.

3. 1. 8.—Clearances.

The horizontal clearance shall be the clear width, and the verticalclearance the clear height, available for the passage of vehicular traffic,as shown on the clearance diagrams.

Unless otherwise provided, the several parts of the structure shall be

constructed to secure the following limiting dimensions or clearances fortraffic :

The clearances and width of roadway for 2-lane traffic shall be notless than those shown in figure 1. The roadway width shall be increasedat least 10 feet and preferably 12 feet for each additional lane of traffic.

3. 1. 9.—Curbs and Safety Curbs.

The face of the roadway curb is defined as the sloping or vertical surfaceon the roadway side of the curb. Horizontal measurements of roadwayand curb widths are given from the bottom of the face, or, in the case ofstepped back curbs, from the bottom of the lower face for roadway widths.

The face of the roadway curb shall be not less than 12 inches from thatportion of the structure above the elevation of the top of the curb andnearest the roadway except in those cases where the clear roadway widthis equal to or greater than the shoulder width but not less than the approach

DESIGN 123

pavement width plus 12 feet, in which case the 12-inch clearance may be

omitted, thus making the provision of a curb optional. The curb heightshall be not less than 9 inches above the adjacent finished surface of theroadway, when not otherwise determined or provided by law. That portionof a curb more than 10 inches above the roadway surface shall be steppedback or sloped back so that no part of a vehicle except the tires may comein contact with it.

Curbs widened to provide for occasional pedestrian traffic shall bedesignated "Safety Curbs." Safety curbs shall be not less than l'-6" wide.

CURB -12"MINIMUM

ROADWAY

CURB

NOT LESS THAN 26-0M BUTNOT LESS THAN 6'- d" GREATER

THAN APPROACH PAVEMENT WIDTHSEE FOOTNOTE

HORIZONTAL CLEARANCE

2Hr

CLEARANCE DIAGRAMTWO-WAY HIGHWAY TRAFFIC

FIGURE I

uoz<

<UJ_1V_l<u

ou

Footnote—For important roads, carrying or likely to carry fast and heavy traffic or largepercentages of trucks, roadway widths greater than the above minimums should be given consideration.

A reduction of two feet in the above minimum requirements shall be permitted if safetycurbs or contiguous sidewalks are used, or if traffic lane widths are in excess of 12 feet.If both conditions exist, a reduction of four feet shall be permitted.

In special cases where traffic is light and meeting of vehicles on the bridge likely tobe infrequent, or where the bridge exceeds 1,000 feet in length, a width of 24'-0" may bepermitted.

For all bridges under 50 feet in length it is preferable that the overall width shall conform as nearly as practicable to the full cross section of the highway (shoulder to shoulder).

124 HIGHWAY BRIDGES

3. 1. 10.—Railings.

Substantial railings along each side of the bridge shall be provided forto protection of traffic. Consideration shall be given to the architecturalfeatures of the railing to obtain proper proportioning of its various members and harmony with the structure as a whole. Consideration shall alsobe given to avoiding, as far as consistent with safety and appearance,obstruction of the view from passing vehicles.

In general, railings shall be of two classes, as follows :

(1) Roadway railings.(2) Sidewalk railings.

Roadway railings shall have a minimum height of 2 feet 6 inches abovethe roadway adjacent to the curb.

Sidewalk railings shall have a minimum height above the surface ofsidewalk of 3 feet less one-half the horizontal width of the top rail. Clearopenings shall be proportioned with due regard for safety of persons usingthe structure. When the top of a curb is more than 2 feet in width theprovisions for sidewalk railings shall apply.

Provision shall be made for the expansion and contraction of railingsconsistent with the design.

3. 1. 11.—Roadway Drainage.

The transverse drainage of roadways shall be secured by means of asuitable crown in the roadway surface and longitudinal drainage by camber or gradient. If necessary, longitudinal drainage shall be secured bymeans of scuppers, inlets or other suitable means, which shall be of sufficient size and number to drain the gutters adequately. If drainage fixturesand downspouts are required, the downspouts shall be of rigid, corrosiveresistant material not less than 4 inches in least dimension, provided withsuitable clean-out fixtures. The details of flood drains shall be such as toprevent the discharge of drainage water against any portion of the structure. Overhanging portions of concrete floors, preferably shall be providedwith drip beads.

3. 1. 12.—Superelevation.

The superelevation of the floor surface of a bridge on a horizontalcurve shall be provided in accordance with the standard practice of thecommission for the highway construction, except that the superelevationshall not exceed 0.10 foot per foot width of roadway.

3. 1. 13.—Floor Surfaces.

All bridge floors shall have non-skid characteristics.

3. 1. 14.—Blast Protection.

On bridges over steam railroad tracks, metal likely to be injured bylocomotive gases, and concrete surfaces less than 20 feet above the tracks,shall be protected by blast plates. The blast plate shall be placed laterally,so that the center is on a line normal to the plane of the two rails at thecenter line of the track, thus taking into account the direction of blast dueto superelevation. The plates shall be not less than 4 feet wide and shallconsist of wrought-iron, cast-iron, a corrosion and blast resisting alloyor asbestos-board shields, so supported that they may be readily replaced.

DESIGN 125

The thickness of plates and other parts in direct contact with locomotiveblast shall be not less than % inch for cast-iron, % inch for wrought-ironor alloy, % inch for plain asbestos-board and %e inch for corrugated asbestos-board. Bolts shall be not less than % inch in diameter. Pocketswhich may hold locomotive gases shall be avoided as far as practicable. Allfastenings shall be galvanized or of corrosive resistant material.

3. 1. 15.—Utilities.

Where required, provision shall be made for trolley wire supports andpoles, pillars for lights, electric conduits, telephone conduits, water pipesand gas pipes.

3. 1. 16.—Roadway Width, Curbs and Clearances for Tunnels. (See Fig. 2.)

(a) Roadway Width.

The clear width between curbs shall be not less than that specifiedfor bridges.

(b) Clearance Between Walls.

The minimum width between walls of two-lane tunnels shall be 30 feet.

1

VER

TIC

AL

CLE

AR

AN

CE

1

NOT LESS THAN 30 FT.

NO

TLE

SS

TH

AN

14

FT.

r-CURB IB" MINIMUM CURB -

\ I *—T^T

NOT LESS THAN SPECIFIED

1 r

r" FOR BRIDGES 3 S

U

CLEARANCE DIAGRAM FOR TUNNELSTWO-WAY HIGHWAY TRAFFIC

FIGURE 2

126 HIGHWAY BRIDGES

(c) Curbs.

The width of curbs shall be not less than 18 inches. The height of curbsshall be as specified for bridges.

(d) Vertical Clearance.

The vertical clearance, between curbs, shall be not less lihan 14 feet.

3.1.17. —Roadway Width, Curbs and Clearances for Depressed Roadways.

(a) Roadway Width.

The clear width between curbs should be not less than that specified forbridges.

(b) Clearance Between Walls.

The minimum width between walls for depressed roadways carryingtwo lanes of traffic shall be 30 feet.

(c) Curbs.

The width of curbs shall be not less than 18 inches. The height ofcurbs shall be as specified for bridges.

3. 1. 18.—Roadway Width, Curbs and Clearances, Underpasses (UndividedHighways). (See Figure 3.)

NOT LESS THAN 6 FT. WIDER THANAPPROACH PAVEMENT

MINIMUM 30 FT.

CURB 18 MINIMUM

NOT LESS THAN SPECIFIEDFOR BRIDGES

CLEARANCE DIAGRAM FOR

UNDERPASSES

TWO-WAY HIGHWAY TRAFFIC

FIGURE 3

DESIGN 127

(a) Widths.

The clear width between walls or columns shall be not less than 6 feetwider than the approach pavement, but in no case shall the width be lessthan 30 feet.

The clear width between curbs, if used, shall be not less than thatspecified for bridges.

(b) Vertical Clearance.

A vertical clearance of not less than 14 feet shall be provided betweencurbs, or if curbs are not used, over the entire width that is available fortraffic.

(c) Curbs.

Curbs shall be not less than 18 inches in width. The height of curbsshall be as specified for bridges.

SECTION 2—Loads

3. 2. 1.—Loads.

Structures shall be proportioned for the following loads and forces whenthey exist:

(1) Dead load.

(2) Live load.

(3) Impact or dynamic effect of the live load.(4) Wind loads.(5) Other forces, when they exist, as follows:

Longitudinal force, centrifugal force, thermal forces, earthpressure, buoyancy, shrinkage stresses, rib shortening, erectionstresses, ice and current pressure, and earthquake stresses.

Members shall be proportioned as specified under Stresses, section 4.

Upon the stress sheets a diagram or notation of the assumed live loadsshall be shown and the stresses due to the various loads shall be shownseparately.

3. 2. 2.—Dead Load.

The dead load shall consist of the weight of the structure complete,including the roadway, sidewalks, and car tracks, pipes, conduits, cables andother public utility services.

The snow and ice load is considered to be offset by an accompanyingdecrease in live load and impact and shall not be included except underspecial conditions.

If a separate wearing surface is to be placed when the bridge is constructed, or if placement of a separate wearing surface is anticipated inthe future by the commission, adequate allowance shall be made for itsweight in the design dead load. Otherwise provision for a future wearingsurface is not required.

Special consideration shall be given to the necessity for a separatewearing surface for those regions where the use of chains on tires isanticipated.

128 HIGHWAY BRIDGES

Where abrasion of concrete is not anticipated the traffic may beardirectly on the concrete slab. If considered desirable, Yi inch or more maybe added to the slab for a wearing surface.

The following weights are to be used in computing the dead load :

Weight per cubic footpounds

Steel or cast steel 490Cast iron 450Aluminum alloys 175Timber (treated or untreated) 50Concrete, plain or reinforced 150Compacted sand, earth, gravel or ballast 120Loose sand, earth and gravel 100Macadam or gravel, rolled 140Cinder filling 60Pavement, other than wood block 150Railway rails, guard rails, and fastenings (per

linear foot of track 200Stone masonry 170Asphalt plank, 1 inch thick 9 lbs. per square foot

(a) Loads on Culverts.

Earth pressures or load on culverts may be computed ordinarily as theweight of earth directly above the slab. In order to have the effect of increasing the allowable design dead load stresses 40 per cent more thanallowed for live load, the effective weight of earth backfill may be takenas 70 per cent of its actual weight.

(b) Rigid Culverts.

For definite conditions of bedding and backfill, the principles of soilmechanics may be applied. The following are recommended formulas forthese conditions:

(1) Culvert in trench on unyielding subgrade, or culvert untrenchedon yielding foundation.

P=WH

(2) *Culvert untrenched on unyielding foundation (such as rock orpiles).

P=W (1.92 H—0.87 B) for H>1.7 B

.385H

P = 2.59BW^e

B -

l^fo

r

H < 1 .7 B

where P=the unit pressure in pounds per square foot due to earth backfillB= width in feet of trench, or in case there is no trench, the overall width

of the culvertH = depth in feet of fill over culvertW= effective weight per cubic foot of fill material, which may be taken as

70 percent of actual weight in accordance with above stated provisions.

* Note : Formula ( 2 ) has been derived from Iowa Engineering Experiment Station Bulletin 96, "The Theory of External Loads on Closed Conduits in the Light of The Latest Experiments," by Anson Marston, Director, February 19, 1930.

3. 2. 3.—Live Load.

The live load shall consist of the weight of the applied moving loadof vehicles, cars and pedestrians.

DESIGN 129

3. 2. 4.—Overload Provision.

The following provision for overload shall apply to all loadings except

the H 20 and H 20-S 16 loadings.

Provision for infrequent heavy loads shall be made by applying in any

single lane an H or H-S truck as specified, increased 100 per cent, and

without concurrent loading of any other lanes. Combined dead, live andimpact stresses resulting from such loading shall not be greater than150 per cent of the allowable stresses allowed herein. The overload shallapply to all parts of the structure affected, including stringers, but excepting flooring.

3. 2. 5.—Highway Loadings.

(a) General.

The highway live loadings on the roadway of bridges or incidentalstructures shall consist of standard trucks or of lane loads which areequivalent to truck trains. Two systems of loading are provided, theH loadings and the H-S loadings, the corresponding H-S loadings beingheavier than the H loadings.

(b) H Loadings.

The H loadings are illustrated in Figures 4 and 5. They consist ofa two-axle truck or the corresponding lane loading. The H loadings aredesignated H followed by a number indicating the gross weight in tons ofthe standard truck.

(c) HS Loadings.

The H-S loadings are illustrated in figures 5 and 6. They consistof a tractor truck with semi-trailer or of the corresponding lane loading.The H-S loadings are designated by the letter H followed by a numberindicating the gross weight in tons of the tractor truck and the letter Sfollowed by the gross weight in tons of the single axle of the semi-trailer.The variable axle spacing has been introduced in order that the spacingof axles may approximate more closely the tractor trailers now in use.The variable spacing also provides a more satisfactory loading for continuous spans, in that heavy axle loads may be placed on adjoining spansto produce maximum negative moment.

(d) Classes of Loadings.

Highway loadings shall be of five classes: H 20, H 15, H 10, H 20-S 16and H 15-S 12. Loadings H 15 and H 10 are 75 per cent and 50 per cent,respectively, of loading H 20. Loading H 15-S 12 is 75 per cent of loadingH 20-S 16. If loadings of weights other than those designated are desired,they shall be obtained by proportionately changing the weights shown forboth the standard truck and the corresponding lane loads.

(e) Designation of Loadings.'The policy of affixing the year to loadings, to identify them, was

instituted with the publication of the 1944 edition in the following manner:H10 Loading, 1944 Edition shall be designated H10-44H15 Loading, 1944 Edition shall be designated H15-44H20 Loading, 1944 Edition shall be designated H20-44H15-S12 loading, 1944 Edition shall be designated H15-S12-44H20-S16 Loading, 1944 Edition shall be designated H20-S16-44

The affix remains unchanged until such time as the loading specification is revised. The same policy for identification shall be applied, for

130 HIGHWAY BRIDGES

future reference, to loadings previously adopted by the American Association of State Highway Officials.

C f ) Minimum Loading.

For trunk highways, or for other highways which carry, or which may

carry, heavy truck traffic, the minimum live load shall be the H15-S12designated herein.

Noth: In explanation of the derivation of the lane loadings, the H lane loading: approximates the truck train loading included in the 1935 A. A. S. H. O. Specifications given inAppendix C. The H15-S12-44 lane loading approximates the H 15 standard truck followedand preceded by 11^4-ton trucks spaced 30 feet apart (between axles). The H 20-S 16-44lane loading approximates the H 20 standard truck followed and preceded by 15-ton trucksspaced 30 feet apart (between axles).

3. 2. 6.—Traffic Lanes.

Where the spacing of main supporting members exceeds 6.5 feet for timber floors or 10.5 feet for concrete or steel grid floors, the lane loading orstandard trucks shall be assumed to occupy a width of 10 feet. These loads

Wcshall be placed in design traffic lanes having a width of W= —

N.

Where Wc=Roadway width between curbs exclusive of median strip.N = Number of design traffic lanes as shown in the following

table,and W= Width of design traffic lane

Wc (in feet) N20 to 30 inc 2

over 30 to 42 inc 3

over 42 to 54 inc 4over 54 to 66 inc 5

over 66 to 78 inc 6

over 78 to 90 inc 7

over 90 to 102 inc 8



The lane loadings or standard trucks shall be assumed to occupy anyposition within their individual design traffic lanes (W) which will producethe maximum stress.

3. 2.7. —Standard Trucks and Lane Loads.

The wheel spacing, weight distribution, and clearance of the standardH and H-S trucks shall be as shown in figures 4 and 6 and correspondinglane loads shall be as shown in figure 5.

Each lane loading shall consist of a uniform load per linear foot oftraffic lane combined with a single concentrated load (or two concentratedloads in the case of continuous spans —see 3.2.8 (c) ) , so placed on thespan as to produce maximum stress. The concentrated load and uniformload shall be considered as uniformly distributed over a 10-foot width ona line normal to the center line of the lane.

For the computation of moments and shears, different concentratedloads shall be used as indicated in figure 5. The lighter concentrated loadsshall be used when the stresses are primarily bending stresses and theheavier concentrated loads shall be used when the stresses are primarilyshearing stresses.

DESIGN 131

W = TOTAL WEIGHT OF TRUC K AND LOAO

I- IW j

H 20-44 8.000- LBSH 15-44 6,000 -LBS-H 10-44 4,000- LBS.

32,000-LBS. *24,000-LBS-16,000-LBS.

-14-0-

0.1 W-

-E

WIDTH OF EACH REAR TIRE EQUALS MNCH

PER TON OF TOTAL WEJGHT OF LOADED TRUCK-

0.1 W

lO-o'cLEARANCE&LOAD LAME WIDTH

2-0" 6'-0M

CURB->

STANDARD H TRUCKSFIGURE 4

* In the design of floors (concrete slabs, steel grid floors, and timber floors) for H-20 orH-20-S-16 loading, one axle load of 24,000 pounds or two axle loads of 16,000 pounds each,spaced 4 feet apart shall be used, whichever produces the greater stress, instead of the 32,000-pound axle shown.

132 HIGHWAY BRIDGES

3. 2. 8.—Application of Loadings.

(a) Traffic Lane Units.

In computing stresses, each 10-foot lane loading or single standardtruck shall be considered as a unit, and fractional load lane widths or fractional trucks shall not be used.

(b) Number and Position, Traffic Lane Units.

The number and position of the lane loadings or truck loading shall be

as specified in article 3. 2. 6 and whether lane loading or truck loading shallbe such as to produce maximum stress, subject to the reduction specifiedin article 3. 2. 9.

(c) Lane Loadings—Continuous Spans.

The lane loadings, shown in figure 5, shall be modified as follows forthe design of continuous spans: The lane loadings shall consist of the loads

18,000 FOR MOMENT *

1

H20-44 LOADINGH 20 -S 16-44 LOADING

L-CONCENTRATED LOAD

-G53,500 FOR MOMENT *

500 FOR SHEAR

♦ --UNIFORM LOAD 400.LBS. PER LINEAR FOOT OF LOAD LANE

H 15-44 LOADING

H I5-SI2-44 LOADING

-CONCENTRATED LOAD9,000 FOR MOMENT *

{9,000

F

13,000 F OR SHEAR

JiyUNIFORM LOAD 320.LBS. PER LINEAR FOOT OF LOAD LANE

HIO-44 LOADING

H LANE AND HS LANE LOADINGS

FIGURE 5

* Note : For the loading of continuous spans involving lane loading refer to article3.2.8 (c) which provides for an additional concentrated load.

DESIGN 133

shown in figure 5 and in addition thereto another concentrated load ofequal weight shall be placed in one other span in the series in such positionas to produce maximum negative moment.

Cd) Loading for Maximum Stress.The type of loading, whether lane loading or truck loading, to be used,

and whether the spans be simple or continuous, shall be the loading whichproduces the maximum stress. The moment and shear tables given in

H20-SI6 -44 8,000 -LBS.H 15-512 -44 6,000- LBS.

32,000 LBS:24,000 LBS.

32,000 LBS. *24,000 LBS.

-t0'|w—h

—|- oVw^j-

- WIDTH OF TIRES SHALL BE THE

SAME AS THE STANDARD H TRUCKS-

•0.4* - . 0.4VV-

W=COMBIN€D WEIGHT ON THE FIRST TWO AXLES WHICH IS THE SAME AS FOR THECORRESPONDING H TRUCK

V-VARIABLE SPACING - 14 FEET TO 30 FEET, I N C LUSI V E. SPACI NG TO B EUSED IS THAT WHICH PRODUCES MAXIMUM STRESSES.

lO-o'cLEARANCE 8c LOAD LANE WIDTH

2-0 t'-o" 2-0_

CURB-,

STANDARD H-S TRUCKS

FIGURE 6

* In the design of floors (concrete slabs, steel grid floors, and timber floors) for H-20 orH20-S16 loading, one axle load of 24,000 pounds or two axle loads of 16,000 pounds each,

spaced 4 feet apart shall be used, whichever produces the greater stress, instead of the 32,000-pound axle shown.

134 HIGHWAY BRIDGES

appendix A show which loading controls for simple spans. The axle spacingfor H-S trucks shall be varied between the specified limits to producemaximum stresses.

For continuous spans, the lane loading shall be continuous or discontinuous, as may be necessary to produce maximum stresses, and theconcentrated load or loads as specified in paragraph (c) shall be placed insuch position as to produce maximum stresses.

3. 2. 9.—Reduction in Load Intensity.Where maximum stresses are produced in any member by loading any

number of traffic lanes simultaneously, the following percentages of theresultant live load stresses shall be used in view of improbable coincidentmaximum loading:

The reduction in intensity of floor beam loads shall be determined as

in the case of main trusses or girders, using the width of roadway which ',

must be loaded to produce maximum stresses in the floor beam.

3. 2. 10.—Electric Railway Loading.If highway bridges carry electric railway traffic, the railway loading

shall be determined on the basis of the class of traffic which the bridge maybe expected to carry. The possibility that the bridge may be required tocarry the freight cars of steam railroads shall be given consideration.

3. 2. 11.—Sidewalk, Curb, Safety Curb and Railing, Loading.

(a) Sidewalk Loading.

Sidewalk floors, stringers, and their immediate supports, shall be de

signed for a live load of 85 pounds per square foot of sidewalk area.Girders, trusses, arches and other members shall be designed for thefollowing sidewalk live loads per square foot of sidewalk area:

P = live load per square foot (maximum, 60 lbs. per sq. ft.).L = loaded length of sidewalk in feet.W= width of sidewalks in feet.

In calculating stresses in structures which support cantilevered sidewalks, the sidewalk shall be considered as fully loaded on only one side ofthe structure if this condition produces maximum stress.

(b) Curb Loading.Curbs shall be designed to resist a lateral force of not less than 500

pounds per linear foot of curb, applied at the top of the curb, but at apoint not over 10 inches above the floor.

(c) Safety Curb Loading.

Safety curbs, or wide curbs provided for occasional use of pedestrians,shall be designed for loads specified in paragraph (a) if the curb is morethan 2 feet in width. If 2 feet or less in width, no live load shall be applied.

One or two lanes. .

Three lanesFour lanes or more

Percent100

9075

Spans 0 to 25 ft. in length 85 lbs.Spans 26 to 100 ft. in length 60 lbs.Spans over 100 ft. in length according to the formula

DESIGN 135

(d) Railing Loading.

(1) Roadway Railings.

Top members of roadway railings shall be designed to resist a

lateral horizontal force of 150 pounds per linear foot together with a

simultaneous vertical force of 100 pounds per linear foot applied atthe top of the railing. When curbs are 10 inches or less in height,lower rails shall be designed to resist a lateral horizontal force of 300pounds per linear foot; or if there is no lower rail, the web membersshall be designed to resist a horizontal force of 300 pounds per linearfoot applied not less than 21 inches above the roadway. For each inchof height of curb above 10 inches, this lateral horizontal force may be

reduced 15 pounds per linear' foot, but this force shall not be less than150* pounds per linear foot. The horizontal forces shall be appliedsimultaneously. Railings without webs and with single rails shall bedesigned for the forces specified above for lower rails.

(2) Sidewalk Railings.

Sidewalk •railings shall be designed to resist the same forces as

those specified for roadway railings, subject to the same restrictionsconcerning curb heights. Where through trusses, girders, or archesseparate the sidewalk and roadway or where sidewalks are protectedby curb railings, the sidewalk railings shall be designed only for theforces specified for the top rail.

3. 2. 12.—Impact.

Live load stresses produced by H or H-S loadings shall be increasedfor items in Group A by allowance at stated herein, for dynamic, vibratoryand impact effects. Impact shall not be applied to items in Group B.

(a) Group A.

(1) Superstructure, including steel or concrete supporting columns,steel towers, legs of rigid frames and generally those portions of thestructure which extend down to the main foundation.

(2) The portion above the ground line of concrete or steel piles whichare rigidly connected to the superstructure as in rigid frame or continuousdesigns.

(b) Group B.

(1) Abutments, retaining walls, piers and piling except Group (A)(2).

(2) Foundation pressures and footings.

(3) Timber structures.(4) Sidewalk loads.(5) Culverts and structures having cover of 3 feet or more.

(c) Impact Formula.

The amount of this allowance or increment is expressed as a fractionof live load stress, and shall be determined by the formula:

I=ETl25 in which

I=impact fraction (maximum 30 per cent).L=length in feet of the portion of the span which is loaded to produce

the maximum stress in the member.

136 HIGHWAY BRIDGES

For uniformity of application the loaded length "L" shall be especiallyconsidered as follows:

For roadway floors, use the design span length.For transverse members, such as floor beams, use span length of

member.For computing truck load moments use span length, except for canti

lever arms use the length from moment center to far end of truck.For shear due to truck loads use length of the loaded portion of span

from the point under consideration to the reaction, except for cantileverarms use 30 per cent.

For continuous spans use length of span under consideration for positive moment, and use average of two adjacent loaded spans for negativemoment.

For culverts with cover 0' to 1' 0" inc. 1=30%" l'l"to2' 0" inc. 1=20%" " " " 2' 1" to 2' 11" inc. 1=10%

3. 2. 13. —Longitudinal Forces.

Provision shall be made for the effect of a longitudinal force of 5 percent of the live load in all lanes, using lane loads, with concentrated loadfor moment, and no impact. The reductions in load intensity of article3. 2. 9. shall apply. This force shall be considered as acting 4 feet abovethe floor. The force assumed is based on all traffic headed in the samedirection.

The longitudinal force due to friction at expansion bearings shall alsobe provided for in the design.

3. 2. 14.—Wind Loads.

The following lateral forces shall be applied to all structures, exceptas otherwise provided, in respect to bracing requirements, in section 6,

Structural Steel Design. They shall be considered to act in any horizontaldirection.

(1) The wind force on the structure shall be assumed as a movinghorizontal load equal to 30 pounds per square foot on 1% times the areaof the structure as seen in elevation, including the floor system and railingsand on one-half the area of all trusses or girders in excess of two in the span.

(2) The lateral force due to the moving live load and the wind forceagainst this load shall be considered as acting 6 feet above the roadwayand shall be as follows:

Highway bridges, 200 pounds per linear foot.Reference is made to item (6).

(3) The total assumed wind force shall be not less than 300 poundsper linear foot in the plane of the loaded chord and 150 pounds per linearfoot in the plane of the unloaded chord on truss spans, and not less than300 pounds per linear foot on girder spans.

(4) In calculating the uplift, due to the foregoing lateral forces, inthe posts and anchorage of viaduct towers, highway viaducts shall be considered as loaded on the leeward traffic lane with a uniform load of 400

pounds per linear foot of lane. These loads shall be applied only in casethey increase the net uplift.

(5) A wind pressure of 50 pounds per square foot on the unloadedstructure, applied as specified above in paragraph (1), shall be used if it

DESIGN 137

produces greater stress than the combined wind and lateral forces ofparagraphs (1) and (2). This requirement shall not apply if the provisionof paragraph (6) is effective.

(6) A reinforced concrete floor slab effectively keyed to its support, ora steel grid floor adequately attached to its supports, may be assumed toresist within the superstructure the wind loads specified under item (2).

3. 2. 15.—Thermal Forces.

Provision shall be made for stresses or movements resulting fromvariations in temperature. The rise and fall in temperature shall be fixedfor the locality in which the structure is to be constructed and shall befigured from an assumed temperature at the time of erection. Due consideration shall be given to the lag between air temperature and the interiortemperature of massive concrete members or structures.

The range of temperature shall generally be as follows :

Metal StructuresModerate climate, from 0° to 120° F.Cold climate, from —30° to 120° F.

Concrete Structures Temperature Temperaturerise fall

Moderate climate 30° F. 40° F.Cold climate 35° F. 45° F.

3. 2. 16.—Force of Stream Current, Floating Ice and Drift.All piers and other portions of structures which are subject to the

force of flowing water, floating ice, or drift shall be designed to resist themaximum stresses induced thereby.

Pressure of ice on piers shall be calculated at 400 pounds per squareinch. The thickness of ice and height at which it applies shall be determinedby investigation at the site of the structure.

Effect of flowing water on pier :

P=KV2, whereP= pressure in pounds per square foot,V= velocity of water in feet per second,K=a constant, being 1% for square ends, % for angle ends where

the angle is 30 degrees or less, and % for circular piers.

3.2. 1 7.—Buoyancy.

Buoyancy shall be considered as it affects the design of either substructure, including piling, or of the superstructure.

3. 2. 18.—Earth Pressure.

Structures designed to retain fills shall be proportioned to withstandpressure as given by Rankine's formula; provided, however, that no structure shall be designed for less than an equivalent fluid pressure of 30 poundsper cubic foot.

When highway traffic can come within a distance from the top of thestructure equal to one-half of its height, the pressure shall have added to ita live load surcharge pressure equal to not less than 2 feet of earth.

Where an adequately designed reinforced concrete approach slab supported at one end by the bridge is provided, no live load surcharge need be

considered.

138 HIGHWAY BRIDGES

All designs shall provide for the thorough drainage of the back-fillingmaterial by means of weep holes and crushed rock, pipe drains or graveldrains, or by perforated drains.

SECTION 3—Distribution of Loads

3. 3. 1.—Distribution of Wheel Loads to Stringers and Floor Beams.

(a) Position of Loads for Shear.

In calculating end»shears and end reactions in transverse floor beamsand longitudinal beams and stringers, no lateral or longitudinal distributionof the wheel load shall be assumed for the wheel or axle load adjacent tothe end at which the stress is being determined. For loads in other positions on the span, the distribution for shear shall be determined by themethod prescribed for moment, except that the calculation of horizontalshear in rectangular beams shall be in accordance with article 3. 4. 14.

(b) Bending Movement in Stringers.

In calculating bending moment in longitudinal beams or stringers, nolongitudinal distribution of the wheel loads shall be assumed. The lateraldistribution shall be determined as follows :

v

(1) Interior Stringers.Interior stringers shall be designed for loads determined in accordance

with the following table :

One traffic lane,fraction of a wheel load to

each stringer

Two or more traffic lanes,fraction of a wheel load to

each stringerKind of floor

S Splank

4.0

S

8.75

S

Strip 4 inches in thickness,wood block on 4-inch planksubfloor or multi-thicknessplank more than 5 inches

4.5 4.0

Strip 6 inches or more in S S

5.0 4.25If S exceeds 5.0 ft.

see footnote*If S exceeds 6.5 ft.

see footnote*

S S



see footnote*

Steel grid (less than 4 inchesthick)

S S

4.5 4.0

Steel grid (4 inches or more)S S



see footnote*

S=average spacing of stringers in feet.Spline and dowled flooring shall have the same distribution as strip floors of equivalent

thickness.* In this case the load on each stringer shall be the reaction of the wheel loads, assuming

the flooring between stringers to act as a simple beam.

DESIGN 139

(2) Outside Stringers.The live load supported by outside stringers shall be the reaction of the

truck wheels, assuming the flooring to act as a simple beam betweenstringers.(3) Total Capacity of Stringers.

The combined load capacity of the beams in a panel shall not be lessthan the total live and dead load in the panel.

(c) Bending Moment in Floor Beams (Transverse).In calculating bending moments in floor beams no transverse distribu

tion of the wheel loads shall be assumed.If longitudinal stringers are omitted and the floor is supported directly

on floor beams, the beams shall be designed for loads determined in accordance with the following table :

Fraction of wheel load to eachfloor beamKind of floor

S

4

Strip 4 inches in thickness, wood block on 4-inch planksubfloor or multi-thickness plank more than 5 inches thick.

S

4.5

S*

5

S*

6

Steel grid ( less than 4 inches thick )S *

4.5

S *

6

S=spacing of beams in feet.Spline and doweled flooring shall have the same distribution as strip floors of equivalent

thickness.* If S exceeds denominator, the load on the beam shall be the reaction of the wheel loads

assuming the flooring between beams to act as a simple beam.

3, 3, 2. —Distribution of Loads and Design of Concrete Slabs,*

(a) Bending Moment,

Bending moment per foot width of slab shall be calculated accordingto methods given under Cases A, B and C.

In Cases A, B and C:

S=effective span length as defined under "Span Lengths"E=width of slab over which a wheel load is distributedN = maximum number of lanes of traffic permissible on bridge

* The slab distribution set forth herein is based, substantially, upon the "Westergaard"theory. The following references are furnished concerning the subject of slab design :

Public Roads, March, 1930, "Computation of Stresses in Bridge Slabs Due to WheelLooads," by H. M. Westergaard.

University of Illinois Bulletin No. 303, "Solutions for Certain Rectangular Slabs Continuous Over Flexible Supports," by Vernon P. Jensen ; Bulletin 304, "A DistributionProcedure for the Analysis of Slabs Continuous Over Flexible Beams," by Nathan M.Newmark ; and Bulletin 315, "Moments in Simple Span Bridge Slabs with Stiffened Edges,"by Vernon P. Jensen.

140 HIGHWAY BRIDGES

W= width of roadway between curbs on bridgesW—width of graded roadway across culvertsQ= uniform lane load per linear foot of laneP1 and P2=load on one wheelP1 = load on one wheel of single axleP2=load on one wheel of tandem axleP'= concentrated lane load per lane.

Case A—Main Reinforcement Perpendicular to Traffic

(See note under Case B)Formula for Moments

Distribution of Wheel Loads Freely supported ContinuousSingle Axle Spans Spans

Spans 2' to 7', E = .SS+2.5 +.25^S +.2^8

Spans over 7', E = .4S + 3.75 + .25— S ± .2—E 'E,

'1 andem Axles p., poSpans 2' to 7', E = .36S+2.58 +.25^?S +.2^rS

Spans over 7', E = .063S +4.65 + .23^S ±.2—S.

Note: In the design for H-20 or H20-S16 loads, the single 24,000 pound axle governsfor spans under 10.5 feet and the two 16,000 pound axles govern for spans of 10.5 feet or over.

Case B—Main Reinforcement Parallel to Traffic* Spans 2 to 12 Feet

Formula for moment

Freely supported Continuousspans spans

P PDistribution, E=. 175 S+3.2 +.25 — S +.2 — S

E — ENote:

The formulas for distribution and moment, Cases A and B, includethe effect of all wheel loads placed in positions to produce maximummoments. Continuous spans shall be designed in accordance with the aboveformula unless moments are calculated by more exact methods which maypermit a greater reduction.

Case C—Main Reinforcement Parallel to Traffic* Spans over 12 Feet

Distribution,10N+W P

(a) Wheel loads: E= Load per foot of slab =—4N E

(b) Lane loads:

* In the design for H20 and H20 S16 loads, the single 24,000-pound axle shall be used forspans under 18 feet in accordance with the formulas of cases B & C. For spans 18 feet andover the two 16,000-pound axles govern and the moments obtained from the formulas of CasesB & C using a single axle load of 24,000 pounds shall be increased by the percentage expressedby the formula 1.6 (S-18).

DESIGN 141

Uniform load= per square foot of slab0.5W+5N \

NP'Concentrated load= per foot width of slab

0.5 W+5 N

The moment for slabs over 12 feet shall be calculated as follows : Theloads per foot of slab shall be determined according to the method givenfor distribution of loads. The loads thus determined shall be placed on thespan or spans in position to cause maximum positive or negative moments.The moment shall be calculated in accordance with standard practice fordesign of simple and continuous spans.

(b) Edge Beams (Longitudinal)

Edge beams shall be provided for all slabs having main reinforcementparallel to traffic. The beam may consist of the curb section reinforced, ofa beam support or of additional slab width. It shall be designed to resista live load moment of 0.10 P S where P=the wheel load and

S=span length.

The moment as stated is for a freely supported span. It may be reduced20 per cent for continuous spans unless a greater reduction results from anexact analysis.

(c) Distribution Reinforcement.Reinforcement shall be placed in the bottom of all slabs normal to

the main steel to provide for lateral distribution of the loads. The amountshall be the percentage of the main reinforcing steel required for positivemoment as given by the following formula :

100Percentage = —

g Maximum 50%

where S equals the effective span of the slab in feet.

(d) Shear and Bond Stress in Slabs.

Slabs designed for bending moment in accordance with the foregoingshall be considered satisfactory in bond and shear.

(e) Unsupported Edges, Transverse.

The design assumptions of this article do not provide for the effect ofloads near unsupported edges. Therefore, at the ends of the bridge and atintermediate points where the continuity of the slab is broken, the edges shallbe supported by diaphrams or other suitable means. The diaphramsshall be designed to resist the full moment and shear produced by the wheelloads which can come on them.

(f) Cantilever Slabs.

Under the following formulas for distribution of loads on cantileverslabs, the slab is designed to support the load independent of edge supportalong the end of the cantilever. The distribution given includes the effectof wheels on parallel elements.

I. Reinforcement Perpendicular to Traffic

Each wheel on the element perpendicular to traffic shall be distributedaccording to the following formula:

142 HIGHWAY BRIDGES

E=.8X+3.75P

Moment per foot of slab =— X foot-pounds in which X= distance inE

feet from load to point of support.

2. Reinforcement Parallel to Traffic

The distribution for each wheel load on the element parallel to trafficshall be as follows :

WE=.35 X+3.2 but shall not exceed

2NP

Moment per foot of slab= — X foot-pounds.E

(g) Slabs Supported on Four Sides.

In the case of slabs supported along four edges and reinforced in both

directions, the proportion of the load carried by the short span of the slab

shall be assumed as given by the following equations:

b*For load uniformly distributed, p =

&* + b*b3

For load concentrated at center, p =a3 + W

where p = proportion of load carried by short span,a = length of short span of slab,b = length of long span of slab.

Where the length of the slab exceeds IV2 times its width, the entire loadshall be assumed to be carried by the transverse reinforcement.

The distribution width E for the load taken by either span shall be

determined as provided for other slabs. Moments obtained shall be usedin designing the center half of the short and long slabs. The reinforcingsteel in the outer quarters of both short and long spans may be reduced 50

per cent. In the design of the supporting beams, consideration shall be

given to the fact that the loads delivered to the supporting beams are notuniformly distributed along the beams.

(h) Edge Distance of Wheel Load.

In designing slabs the center line of wheel load shall be assumed to be

1 foot from the face of the curb.

(i) Span Lengths. (See also Article 3. 7. 4.)The following effective span lengths shall be used in calculating distri

bution and moment of slabs continuous over more than two supports.

Slabs monolithic with beam (without haunches) S = clear span.

Slabs supported on steel stringers S = distance between edges of flangesplus V2 of the stringer flange width.

Slabs supported on timber stringers S = clear span plus Vz thicknessof stringer.

For simple spans the span length shall be the distance center to centerof supports but not to exceed clear span plus thickness of slab.

DESIGN 143

3. 3. 3.—Distribution of Wheel Loads Through Earth Fills.

When the depth of fill is 2 feet or more, concentrated loads shall be considered as uniformly distributed over a square, the sides of which are equalto 1% times the depth of fill. When such areas from several concentrationsoverlap, the total load shall be considered as uniformly distributed over thearea defined by the outside limits of the individual areas, but the total widthof distribution shall not exceed the total width of the supporting slab. Forsingle spans, the effect of live load may be neglected when the depth of fillis more than 8 feet and exceeds the span length ; for multiple spans, it may be

neglected when the depth of fill exceeds the distance between faces of endsupports or abutments. When the depth of fill is less than 2 feet the wheelload shall be distributed as in slabs with concentrated loads. When the calculated live load and impact moment in concrete slabs based on distributionof the wheel load through fills as herein outlined exceeds the live load andimpact moment calculated according to article 3. 3. 2 then the latter momentshall be used.

3. 3. 4.—Distribution of Wheel Loads on Timber Flooring.

For the calculation of bending moments in timber flooring each wheelload shall be distributed as follows :

(a) Flooring Transverse.

In direction of span —over width of tire. (H 10 loading 10 inches;H 15 loading 15 inches; H 20 loading 20 inches.)

Normal to direction of span —plank floor, distribution = width of plank.Normal to direction of span — laminated floor, distribution = 15 inches.Spline, or doweled floor —not less than 5% inches thick, distribution = 4

times thickness.Span length = clear distance between stringers plus one-half the width

of one stringer but shall not exceed the clear span plus thickness of floor.

(b) Flooring Longitudinal.

In direction of span —point loading.Normal to direction of span— laminated floor, distribution = width of

wheel plus thickness of floor.Normal to direction of span —plank floor, distribution = width of plank.Spline, or doweled floor —not less than 5% inches thick, distribu

tion = width of wheel plus twice thickness.Span length = clear distance between floor beams plus one-half the

width of one beam but shall not exceed the clear span plus thickness of floor.

(c) Continuous Flooring.

If the flooring is continuous over more than two spans the maximumbending moment shall be assumed as being 80 per cent of that obtained fora simple span.

3. 3. 5.—Steel Grid Floors,

(a) General.

The grid floor shall be designed as continuous and moments reduced asprovided in article 3. 3. 2.

The formulas for distribution of loads provided herein are based uponthere being adequate transfer of the load normal to the main elements.Reinforcement for this purpose shall consist of transverse bars or shapeswelded to the main steel. The strength and details of the transverse reinforcement shall meet with the approval of the engineer.

144 HIGHWAY BRIDGES

(b) Floors Filled with Concrete.

The distribution and bending moment shall be as specified for concreteslabs, article 3. 3. 2. The following items specified in that article shall alsoapply to concrete filled steel grid floors:

Edge beams (longitudinal).Unsupported edges (transverse).Span lengths.

The strength of the composite steel and concrete slab shall be determinedby means of the "transformed area" method. The allowable stresses shallbe as set forth in section 4.

'c ) Open Floors.

A wheel load shall be distributed, normal to the main bars, over a widthof W plus twice the distance center to center of main bars, where W equals1 inch per ton of total weight of loaded truck. Bending moment shall be

calculated as specified in section 3 for concrete slabs. The strength of thesection shall be determined by the moment of inertia method. The allowable stresses shall be as set forth in section 4.

SECTION 4—Unit Stresses, Pile Loads and Bearing Power of Soils

3. 4. 1.—General.For the purpose of application of stresses and pile loads, the loads and

forces shall be divided into two groups:

(a) Group A.

Dead load BuoyancyLive load Earth pressureImpact

(b) Group B.

Longitudinal forces Erection stressesWind loads IceShrinkage stresses CurrentRib shortening EarthquakeCentrifugal force Thermal stressesBack-fill (to original ground line)

Structures designed for Group A loads shall be proportioned so thestresses and loads shall not exceed those set forth in this section.

Structures designed for Group A loads in combination with Group Bloads shall be proportioned for stresses and pile loads set forth herein increased 25 per cent; provided, however, that the resulting sections shall notbe less than required for Group A loading only.

Unit Stresses.

Unless otherwise noted the allowable unit stresses stipulated hereinare given in pounds per square inch.

Steel Structures

Unless otherwise specified or noted on the plans, it shall be assumedthat the steel is to be Structural Carbon Steel, A. S. T. M. A7-46 (Eyebars,A7-39). The modulus of elasticity for all grades of steel shall be assumedas 29,000,000 and the coefficient of expansion .0000065.

DESIGN 14S

3. 4. 2.—Structural Carbon Steel—A. S. T. M.—A 7-46 (Eyebars, A 7-39).

Rivet steel, A. A. S. H. 0.—M 97-39 (A. S. T. M.—A 141-39).Pins and rollers, A. S. T. M.—A 235-46 (Class CI).Axial tension, structural steel, net section 18,000Tension in extreme fibers of rolled shapes, girders and built

sections subject to bending 18,000Tension in bolts at root of thread 13,500Axial compression, gross section:

Stiffeners of plate girders 18,000

The permissible unit stress in concentrically loaded columns havingvalues of L/r not greater than 140 may be computed from the followingapproximate formulas, or from the more exact formulas given inAppendix B:

L2Riveted ends 15,000— hi-^r

Pin ends 15,000—^-;

L = length of member, in inches.r = least radius of gyration of member, in inches.

For compression members with values of L/r greater than 140, and forcompression members of known eccentricity, see appendix "B."

Compression in extreme fibers of rolled shapes, girdersand built sections subject to bending (for values of

L/b not greater than 30) 18,000— 5 ^_L = length, in inches, of unsupported flange be

tween lateral connections or knee braces,b = flange width in inches.

Allowable compression in splice material, gross section 18,000Stress in extreme fiber of pins 27,000Shear in girder webs, gross section 11,000Diagonal tension in webs of girders and rolled beams, at sections

where maximum shear and bending occur simultaneously 18,000Shear in power-driven rivets and pins 13,500Shear in turned bolts 11,000Bearing on pins not subject to rotation 24,000Bearing on power-driven rivets, milled stiffeners, and other steel

parts in contact 27,000

(Rivets driven by pneumatically or electricallyoperated hammers are considered power driven.)

Bearing on pins subject to rotation (not due to deflection) 12,000Bearing on turned bolts 20,000

Bearing on expansion rollers and rockers, pounds per linear inch:

p— 13,000Diameters up to 25 inches 600d

20,000

p— 13,000Diameters from 25 to 125 inches 3,000 Vd

20,000

d = diameter of roller or rocker, in inches.p = yield point in tension of steel in the roller or the

base which ever is the lesser. ,

146 HIGHWAY BRIDGES

In proportioning rivets the nominal diameter shall be used.

The effective bearing area of a pin, a bolt, or a rivet shall be itsdiameter multiplied by the thickness of the metal on which it bears.

In metal less than % inch thick countersunk rivets shall not be assumedto carry stress. In metal % inch thick and over, one-half the depth ofcountersink shall be omitted in calculating bearing area.

3. 4. 3.—High Strength Rivets.

High Strength Structural Rivet Steel, A. A. S. H. 0.—M 98-41 (A. S. T.M.— A 195-41).

Shear 20,000Bearing 40,000

3. 4. 4.—Wrought Iron.

°hapes and bars, A. A. S. H. O.—M 100-39 (A. S. T. M.— A 207-39).(A. S. T. M.— A 42-47).

Pipe (A. S T. M.— A 72-45).Tension 14,000Bending on extreme fiber 14,000

3. 4. 5.—Cast Steel and Cast Iron.

For cast steel the allowable unit stresses in compression and bearingshall be the same as those for structural steel. Other allowable unit stressesshall be three-fourths of those for structural steel.

For cast iron of the grades specified in division IV the following allowable unit stresses shall be used:

Bending on extreme fiber 3,000Shear 3,000Direct compression (short columns) 12,000

3. 4. 6.—Bronze or Copper Alloy.

Bearing on bronze or copper alloy bearing and expansion plates . . 2,000

3. 4. 7.—Structural low-Alloy Steel.

This steel is designated: Structural low-alloy steel, A. S. T. M.—A242-46.

The foregoing specifications shall apply to low-alloy steel parts ofbridges except as provided otherwise below and the nomenclature below isthe same unless otherwise defined.

% in. andunder50,000

over J£ in. to1 XA in. inch

45,000

over 1 14 in . to2 in. incl.

40,000

27,000 24,000 22.000

27,000 24,000 22,000

27,000 24,000 22,000

Yield Point, MinAxial tension, structural steel,

net sectionTension in extreme fibers of rolled

shapes, girders and built sections subject to bending

Axial compression, gross section:Stiffeners of plate girders

The permissible unit stress in concentrically loaded columns havingvalues of L/r not greater than 125 for low-alloy steel may be computed fromthe following approximate formulas or by the more exact method, using theformulas given in Appendix B.

DESIGN 147

Riveted ends 22,000-0.56^ 20,000-0.46^ 18,000-0.39^

Pin ends 22,000-0.73^ 20,000-0.61^ 18,000-0.48^

For compression members with values of L/r greater than 125 low-alloysteel, and for compression members of known eccentricity see Appendix B.

Compression in extreme fibers ofrolled shapes, girders and builtsections, subject to bending,gross section.

(Values of L/b not to exceed 25 tj t 2 j.2for low-* loy steel) 27,000-7.50g.2 24,000-6.67^ 22,000-6.11^

Compression, splice material grosssection

Stress in extreme fibers of pinShear in plate girder webs, gross

sectionsDiagonal tension in webs of girders

and rolled beams at sectionswhere maximum shear andbending occurs simultaneously.

Shear in pinsBearing on pins (not subject to

rotation)Bearing on milled stifleners and

other parts in contactBearing on pins subject to rota

tion (not due to deflection)Bearing on rollers and rockers:

Same formulas as in article 3.4.2.

27,00040,000

24,00036,000

22,00032,000

15,000 14,000 12,000

27,00020,000

24,00018,000

22,00016,000

36,000 32,000 28,000

40,000 36,000 32,000

18,000 16,000 14,000

NOTE : For determining the permissible stresses for low.alloy steel the thickness of bevelled flanges or plates shall be the average thickness. For built-up members the plate havingthe greatest thickness shall govern.

3. 4. 8.—Structural Nickel and Structural Silicon Steels.

These steels are designated: structural silicon steel (A. S. T. M.—A94-46) and structural nickel steel (A. S. T. M.— A 8-46).

The foregoing specifications shall apply to silicon or nickel steel partsof bridges except as provided otherwise below and the nomenclature below isthe same unless otherwise defined:

Silicon steel Nickel steelAxial tension, structural steel, net section 24,000 30,000Tension in extreme fibers of rolled shapes, girders

and built sections, subject to bending 24,000 30,000Axial compression, gross section:

Stiffeners of plate girders 24,000 30,000

The permissible unit stress in concentrically loaded columns havingvalues of L/r not greater than 130 for silicon steel or 120 for nickel steelmay be computed from the following approximate formulas or by the moreexact method, using formulas given in Appendix B.

Riveted ends 20,000—0.46^ 24,000— 0.66^

Pin ends 20,000—0.61 j2 24,000—0.86^

148 HIGHWAY BRIDGES

For compression on members with values of L/r greater than 130 forsilicon steel and 120 for nickel steel, and for compression members of knowneccentricity see appendix "B."

Silicon steel Nickel steelCompression in extreme fibers of rolled

shapes, girders and built sections, subjectto bending, gross section (for values ofL/b not greater than 25 for silicon steel, L2 L2or 20 for nickel steel 24,000— 6.67p- 30,000— 8.33

Compression, splice material, gross section . 24,000 30,000Stress in extreme fibers of pins 36,000 44,000Shear in plate girder webs, gross section . . 14,000 17,500Diagonal tension in webs of girders and

rolled beams at sections where maximumshear and bending occurs simultaneously 24,000 27,000

Shear in pins 18,000 22,000Bearing on pins (not subject to rotation) . . 32,000 40,000Bearing on milled stiffeners and other parts

in contact 36,000 44,000Bearing on pins subject to rotation (not

due to deflection) 16,000 18,000Bearing on rollers and rockers:

Same formulas as in article 3. 4. 2.

3. 4. 9.—Unit Stresses for Welding.

The allowable unit stresses in pounds per square inch of effective area ofweld shall be as given in the current specifications of the American WeldingSociety for Welded Highway and Railway Bridges.

3. 4. 10.—Bearing on Masonry.

Bearing on granite masonry 800Bearing on sandstone and limestone masonry 400

Bearing on concrete:Bridge seats, under hinged rockers and bolsters (not subjected

to high edge loading by a deflecting beam, girder, or truss) . . 1,000Bridge seats, under bearing plates or non-hinged shoes (sub

jected to high edge loading by the direct bearing, upon theplate or shoe, of a deflecting beam or birder), average 700

(The above bridge seat unit stresses will apply only where the edge ofbridge seat projects at least 3 inches (average) beyond edge of shoe or plate.Otherwise, the unit stresses permitted will be 75 per cent of the aboveamounts.)

Concrete Structures

3. 4. 11.—Concrete Stresses.

(a) Standard Notations and Assumptions.

L = unsupported length of column, in feet.D = least dimension of column, in feet.

(1) The full dimensions of the concrete section shall be used in thedesign of tied columns.

(2) The diameter of the outer circumference of the spiral hoopingshall be used for the computation of stresses in spiral columns.

(3) For battered columns "D" shall be measured at midheight.

DESIGN 149

fc = permissible extreme fiber stress in compression.f'c =unit ultimate compressive strength of concrete as determined by cylinder

tests at the age of 28 days,fe = permissible unit compressive stress in concrete in eccentrically loaded

columns.e = eccentricity of resultant load as measured from the gravity axis.c~ distance from gravity axis to the extreme fiber in compression, measured

parallel to the plane of bending.r = radius of gyration of gross transformed column section in the plane of

bending.K= ratio of the permissible unit concrete compressive stress for axial loading

to the permissible unit stress in the extreme fibers of the concrete beams.(See formula in appendix D.)

n = ratio of modulus of elasticity of steel to that of concrete. The value ofn, as a function of the ultimate cylinder strength of concrete, shall beassumed as follows:

f'c- 2000-2400 n = 15= 2500-2900 =12=3000-3900 =10= 4000-4900 = 8= 5000 or more = 6

p = ratio of cross-sectional area of longitudinal reinforcing bar to the grossarea of the concrete section,

p' = ratio of volume of spiral reinforcement to volume of the concrete core.

Coefficients:Thermal, .000006. Shrinkage, .0002.

f''c = permissible unit compressive stress in concrete when L/D is greaterthan 12.

(b) General.It shall be understood that concrete structures designed in accordance

with these specifications are designed on the basis of concrete having anultimate strength of 3,000 lbs. per square inch at 28 days; unless anotherultimate strength is stipulated on the plans, in which case the allowablestresses shall be noted on the plans.

The extreme upper limit of ultimate strength upon which allowablestresses are based shall be 4,500 pounds per square inch.

Allowable Stresses

(c) Flexure.Values iff'c =30 00

Extreme fiber in compression fc = }i f 'c 1000Extreme fiber in tension, plain concrete, primarily in foot

ings fc = .03 f'c 90Extreme fiber in tension, reinforced concrete None

(d) Shear.Beams without web reinforcement:

Longitudinal bars not anchored or plain concretefootings 02 f'c 60

Longitudinal bars anchored 03 f'c 90Beams with web reinforcement:

Longitudinal bars not anchored 046 f'c 140Longitudinal bars anchored 06 f'c 180

Punching shear 053 f'c 160

(e) Bond on Piles (in Seals).Timber, steel or concrete piles, 10 lbs. per square inch. (Providing the

pile has the resistance to pull thereby induced.)

150 HIGHWAY BRIDGES

(f) Bearing on Bridge Seats.

Refer to article 3. 4. 10.

(g) Columns —

Flexure and Direct StressValue if f'c=3000

CI) Axially loaded piers and pedestals with L/D equalto or less than 3. fc = .25f \> 750

( 2) Axially loaded columns with L/D from 3 to 12 inclusive, reinforced with longitudinal bars: r -i

With lateral ties fc = .25f'cl l + (n-l)p|

Spirally reinforced fc = (.25 +12p')f

'c[l + (n - l)p]

(3) Axially loaded columns with L/D greater than 12. f \ =(l.33 -3^5)^

(4) Eccentrically loaded columns

r2

With L/D equal to or less than 12 fe = fc

With L/D greater than 12 fe = f",1+SS

+r»

1+Kec

Values of fe,

when L/D is equal to or lessappendix D. For values of fe

,

when L/D is

fc/fo to the values given in the diagram.

3. 4. 12.—Reinforcement.

than 12, are given in the diagramgreater than 12, apply the factor

Structural Intermediate *Grade Grade

Steel reinforcement:Tension in flexural members 18,000 20,000Tension in web reinforcement 16,000 16,000Compression:

"n" times the compression in the surrounding concrete.

Bond:Bars not anchored .05 fo .05 f'c

(maximum 150) (maximum 150)Bars adequately anchored by hooks

or otherwise .075 f'c .075 f'c(maximum 225) (maximum 225)

NOTE: The above allowable bond stresses fhall be reduced for footings as provided underthe item "Reinforcement," Article 3.5.2 (f).

* According to article 4. 5. 1, it is required that the grade of reinforcing ateel shall

be either "Structural" or "Intermediate," unless otherwise stipulated. In the event allowablestresses for "Intermediate Grade" steel are used, it is necessary to modify article 4. 5. 1 byspecial provision, to require that "Intermediate Grade" steel be furnished. The grade required should also be noted on the plans.

DESIGN 151

Timber Structures

3. 4. 13.—Standard Stress Grades and Working Stresses.

The following are the allowable unit stresses for treated timber :

Grades and species Fiber stress Maximum Compression Modulusin bending horizontal perpendicular ofor tension shear to grain elasticity

1800#f Dense Douglas Fir(Coast and Inland) 1800 120 380 1,600,000

1800#f Dense Larch 1800 120 380 1,300,0001800 #f Dense Longleaf or

Dense Shortleaf South-1800 120 380 1,600,000

1600#f Close-grainedDouglas Fir (Coast) 1600 100 345 1,600,000

1600#f Close-grainedDouglas Fir (Inland)... 1600 80 335 1,500,000

1600#f Close-grained1600 100 345 1,300,000

1600#f Dense Longleaf orDense Shortleaf Southern Pine 1600 120 380 1,600,000

1600 #f Close-grained Red-1600 80 267 1,200,000

1400 #f Tidewater Red1400 120 300 1,200,000

1400 #f Oak 1400 120 500 1,500,000

1400#f Dense Longleaf1400 100 380 1,600,000

1400#f Close-grained Red-1400 80 267 1,200,000

1200#f Douglas Fir(Inland) 1200 80 315 1,500,000

1200#f Larch 1200 100 325 1,300,0001200 #f Dense Shortleaf

Southern Pine .... 1200 100 380 1,600,000

1200#f Close-grained Red-1200 70 267 1,200,000

1000 #f Western Red .

Cedar 1000 100 200 1,000,0001200#f Port Orford Cedar. 1200 100 250 1,500,0001200#f Douglas Fir

(Coast) ... 1200 100 325 1,600,0001100#f Port Orford Cedar. 1100 80 250 1,500,0001100#f Tidewater Red

1100 100 300 1,200,000

1100#f Oak 1100 100 500 1,500,000

Compression Parallel to Grain,Grades and Species

Short Columns

1200 #c Tidewater red cypress 12001200# - Close-grained Douglas fir (coast) .

1200#c Close-grained Douglas fir (inland)1200#c Close-grained larch1200#c Dense longleaf or dense shortleaf southern pine

1^001200#c Close-grained redwood1^001100#c Douglas fir (coast) "J™1100#c Douglas fir (inland)

1100#c Larch1100#cOak n00

152 HIGHWAY BRIDGES

Compression Parallel to Grain, Short Columns

Grades and Species

1100#c Close-grained redwood 1100

1100#c Port Orford cedar 1100

1000#c Tidewater red cypress 1000

1000#c Oak 1000

1000#c Dense longleaf southern pine 1000

1000#c Close-grained redwood .' 1000

800#c Western red cedar 800

For untreated timber, except for temporary use, the stresses given inthe above table shall be reduced to the following percentages:

Kind of stress Per centExtreme fiber in bending 87%Compression perpendicular to grain 70Compression parallel to grain 92Horizontal shear 100Modulus of elasticity 100

3. 4. 14.—Formulas for the Computation of Stresses in Timber,

(a) Horizontal Shear in Rectangular Beams.

Horizontal shear in beams shall be computed from the maximum shearoccurring at a distance from the support equal to three times the depthof the beam, or at the quarter point whichever be the lesser distance fromthe support. The live load to be used in computing horizontal shear in eachbeam shall be one-half the sum of the wheel load and the live load used incomputing the maximum moment.

The shear shall be calculated according to the following formula:

3 Vs~2 bd

Wheres= maximum unit shear per square inchb = width of beam in inchesd = depth of beam in inchesV=end shear in pounds

(h) Axial Compression in Rectangular Columns. (Hinged ends assumed.)

P = total load in poundsA = area of cross section in square inchesC =safe stress in compression parallel to grain for short columnsL = unsupported length in inchesD — least dimension in inchesE = modulus of elasticity

for any grade, for factor of safety of 3.

Short columns. g not over 11

Intermediate columns, g between 11 and K.

DESIGN 163

Long columns. g equal to or greater than K, but not to exceed 50

P .274 E

(c) Axial Compression on Connector-Joined Spaced Columns. (Hinged endsassumed).

Timber connectors shall include devices used in the contact surfaces oftimber joints to increase the strength or shear resistance over that ofbolted joints.

^Xl.25 for unstayed portion of individual members shall not exceed 50

^of individual members of spaced columns shall not exceed 80

g for entire column shall not exceed 50

Spacer blocks. A single spacer block shall be within 5 per cent of Lfrom center of column. If more than one spacer block is used, the distancebetween any two blocks shall not exceed one-half the distance betweencenters of connectors in the end blocks. Connectors of the same size as

used in the end block shall be used for spacer blocks under these conditions.Spacer blocks shall be in contact with the full width of sides of the maintimbers. Laminated columns and spaced columns with less than full widthspacer pieces shall not be permitted.

Intermediate columns.

Condition A. When connectors are within ^ from the ends of the column —

K2 = 1.5811 K

Condition B. When connectors are placed from ^ to ^ from the end and long

blocks are used.

K3 = 1.732 KPA

Long columns.

P .274 EX2.5

X'(fe)'P .274 EX3

for condition A

for condition B

(d) Safe Load on Round Columns.

The safe load on a round column shall not exceed that permitted for asquare column of the same cross-section area. The diameter of a tapered

154 HIGHWAY BRIDGES

column shall be measured at a point one-third the length from the smallend and in no case shall it be assumed as more than 1% times the leastdiameter at its small end. The compressive stress at the small end of atapered column shall not exceed the allowable stress for a short column.

(e) Notched Beams.Beams notched upward in the bearing face on supports shall be limited

to maximum end load R as determined by the formula.

D 2bd2 HR

3h~

R = maximum end loadH = maximum permissible stress in shearb = breadth of beamd = depth of beam above the notchh = total depth of beam

(f) Bearing on Inclined Surfaces.

N- PQPsin2 e+Q cos2 e

N =unit bearing on an inclined surfaceP=unit stress in compression parallel to the grainQ =unit stress in compression perpendicular to the grain0= angle in degrees between the direction of load and the direction

of grain

(g) Timber Connectors.Timber connectors shall consist of devices to be used at surfaces of

contact in bolted timber joints, to increase the strength or shear resistanceof wood-to-wood or wood-to-steel connections.

Allowable loads, spacing of connectors, edge and end distance, boltand washer sizes and other details of design shall be those recommended orapproved by the United States Forest Products Laboratory, or the allowable loads may be determined by actual tests of full sized joints for eachcondition of connector use in accordance with their procedure.

Miscellaneous

3. 4. 15.—Bearing Power of Foundation Soils. Determination of BearingPower.*

When required by the engineer, the bearing power of the soil in excavated foundation pits shall be determined by loading tests.

The following tabulation of the bearing power of broad basic groupsof materials may be used as an aid to the judgment in the absence of moredefinite information:

Safe bearing powerTons per square foot

Material Min. Max.Alluvial soils V2 1

Clays 1 4

Sand, confined 1 4

Gravel 2 4

Cemented sand and gravel 5 10

Rock 5

* For laboratory methods of determining the consolidation characteristics of foundationsoils, see PUBIC Roads, March, 1937, "The Theory of Soil Consolidation and Testing ofFoundation Soils," by L. A. Palmer and E. S. Barber.

DESIGN 155

3. 4. 16.—Angles of Repose.

Earth, Loam 30° to 45°25 to 3530 to 4515 to 3025 to 4535 to 40

Gravel .

Cinders30° to 40°25 to 4030 to 4525 to 35

Dry Sand. .

Miost SandWet Sand. .Clay

CokeCoal.

Compact earth

In the absence of exact data which has been determined by field investigation and soil analysis, the angle of repose of the material shall be

assumed to be the minimum given in the table.

3. 4. 17.—Bearing Value of Piling.

(a) General.

The design loads for pile3 shall not be greater than the minimum valuewhich shall be determined for Case A, Case B and Case C; where Case A isthe capacity of the pile as a structural member, Case B is the capacity of thepile to transfer its load to the ground and Case C is the capacity of theground to support the load delivered to it by the pile or piles. The valuesassignable to each of the three cases shall be determined by making subsurface investigations or tests of sufficient extent to justify the assumed designvalues used for the particular condition of support under consideration.

In determining the bearing value of piles for use in designing, consideration shall be given to all information available relative to the subsurfaceconditions. Consideration shall also be given to :

(1) The difference between the supporting capacity of a single pile anda group of piles.

(2) The capacity of the underlying strata to support the load of thepile group.

(3) The effect of driving additional piles and the effect of their loads onadjacent structures.

(4) Possibility of scour and its effect.

(b) Case A. Capacity of Pile as a Structural Member.

(1) Piles shall be designed as structural columns. Timber piles shallbe designed in accordance with article 3.4.14, concrete piles in accordancewith article 3.4.11, steel piles in accordance with article 3.4.2, and concrete-filled pipe piles in accordance with article 3.4.11, except that the allowableunit stresses may be increased 20% provided the shell thickness is not lessthan % inch. The area of the shell shall be included in determining the valueof P=percentage of reinforcement. Where corrosion may be expected Meinch shall be deducted from the shell thickness to allow for reduction in section by corrosion. The allowable stresses of articles 3.4.2, 3.4.11 and 3.4.14may be used in all cases where all of the stresses to which the piles may besubjected have been included. These stresses may be increased in accordancewith article 3.4.1. For trestle piles or other piles without lateral support designed for dead load and live load only and where temperature, traction,water pressure and other forces are not considered, the allowable unitstresses specified in articles 3.4.2, 3.4.11 and 3.4.14 shall be decreased 20%.

(2) Required Subsurface Investigations:

Subsurface investigations shall be made which will determine the probable depth of scour or flotation of material and the condition of lateral support of the pik. A pile shall be considered fully supported laterally except

156 HIGHWAY BRIDGES

that portion which is or may be, as a result of scour, in air, water, muck, peat,thin mud or other very plastic or fluid material.

(c) Case B. Capacity of Pile to Transfer Load to the Ground.

(1) Point-bearing Piles. A pile shall be considered to be a point-bearingpile when placed or driven on or into a material which is capable of developing the pile load by direct bearing at the point with reasonable factor ofsafety.

The allowable load at the tip of the pile shall not exceed the following:

(a) For timber piles, 80% of allowable compression parallel to grain,short columns, in accordance with article 3.4.13.

(b) For concrete piles, 0.33f'c in accordance with article 3.4.11.

*(c) For concrete-filled pipe piles, 0.40f'c in accordance with article3.4.11, applied to the total actual area of the concrete and steel.

* (d) For steel piles, 6,000 pounds per sq. in. over the cross sectionalarea of the pile tip.

(2) Friction piles. A pile shall be considered to be a friction pile if itspoint does not rest on or in a material which is capable of developing thepile load by direct bearing at the point.

The load-carrying capacity of friction piles shall be determined by oneor more of the following methods :

(a) Driving and loading test piles. The safe allowable load shall be asdefined by article 2.3.6 (a).

(b) Pile-driving experience in the vicinity. When piles are designed onthe basis of experience in the vicinity, due consideration will be

given to the variation in pile types and lengths, and in the variation of the soil strata. Where possible, the complete driving recordsof all piles in the vicinity shall be examined and compared to thedriving records of the project piles.

(c) Adequate tests of the soil strata through which the pile is to bedriven. These tests should be projected and compared, if possible,to tests of similar material through which piles of known capacityhave been driven.


(a) Point-bearing piles. Sufficient borings shall be made to determinethe presence, position, and thickness of the material which is capable of developing point bearing, and the log of borings shall showthe nature of the overlying strata in order that the extent of lateralsupport may be determined. If the point-bearing stratum is ofdoubtful thickness and quality, the borings shall be made to sufficient depth below this stratum such that the capacity of a frictionpile may be determined.

(b) Friction piles. Borings shall be made to an elevation well belowthe expected elevation of the pile tips and accurate logs of theseborings shall be made. In those cases where the piles are to bedesigned on the basis of soil tests, undisturbed samples shall betaken on all strata which will have Appreciable influence on thecapacity of the pile.

(c) Combination point-bearing and friction pilss. Piles shall be classified as either (1) point-bearing or (2) friction. Those cases

*NOTE: The limitation in (c) and (d) govern except where the toint bearing capacityof the piles is determined by loading test piles.

DESIGN 157

where adequate strength is developed by both point bearing andfriction may be designed under either of these classifications.

(d) Case C. Capacity of the Ground to Support the Load Delivered by thePile.

(1) The capacity of the ground to support the load delivered by the pileshall be determined from the results of the required subsurface investigations.


(a) Point-bearing pile3. Sufficient borings shall be made to determinethe thickness and quality of the stratum in which the point bearingis developed. If the material in which point bearing is developed is ofsufficient thickness and is underlain by a firm material, no reductionwill be made for group action of piles. In general, piles should notrest on a thin stratum of hard material which is underlain by athick stratum of soft or yielding material, but where this conditioncannot be avoided, group action should be considered and the designloads reduced accordingly.

(b) Friction piles. Borings shall be made well below the tips of thepiles in order to determine the characteristics of the underlyingmaterial. In most cases a study of those borings will suffice todetermine whether or not the underlying soil will support the loadsdelivered to it, but in doubtful or special cases, especially largefoundation areas and important footings the material should beinvestigated more thoroughly by soil mechanics methods.A single row of piles shall not be considered as a group providedthat they are not spaced closer center to center than 2% times thenominal diameter or dimension. In those cases where piles aredriven in groups into plastic material, the design load shall bedetermined by the loading of a group of piles or definite allowanceshall be made for the difference between the supporting capacity ofa single pile and a group of piles. (Refer to (g).)

(e) Maximum Design Loads for Piles.

In those cases where it is not feasible to make the required subsurfaceinvestigations or test loads the maximum assumed design load for piles shallbe as given in the table below. These values may be increased 25 per centfor certain combinations of loads as specified in article 3. 4. 1.

The assumed pile loads shall be substantiatedby determining the allowable load by formula, when the piles are driven, asprovided in article 2. 3. 6. (b).

Types of Piles

Size or Diameter Timber Concrete Steel Steelat Butt*, Inches Tons Tons (Friction) Tons Point Bearing

8 1610 18 20 20 6000 pounds per12 20 24

' ~ '24 sq. in. of point

14 24 28 28 area.16 28 3220 .. 4024 50 E? • .

* Timber piles, diameter to be measured 3 feet from butt.

158 HIGHWAY BRIDGES

(f) Uplift.

Friction piles may be considered to resist an intermittent but not sustained uplift equivalent to 40 per cent of the above loads providing properprovision is made for the anchorage at top and sufficient skin friction isdeveloped and in no case shall it exceed the weight of material (buoyancy

considered) surrounding the embedded portion of the pile.

(g) Group Pile Loading.

Where the capacity of a group of piles driven into plastic material isnot determined by test loading, the following Converse-Labarre formula issuggested to determine the reduction of a single pile load for a group pileload:

„ n ,(n-l)m+(m-l)n

WhereE =the efficiency or the decimal fraction of the single pile value to b

used for each pile in the group,n = the number of piles in each row.

m=the number of rows in each group,d = the diameter of the pile,s = center to center spacing of piles

Tan <*, = d/s

<j,

is numerically equal to the angle expressed in degrees.

3. 4. 18.—Moments, Shears and Reactions.

Maximum moments, shears, and reactions are given in tables, appendixA, for H 15, H 20, H 15— S 12 and H 20— S 16 loadings. They are calculated for the standard truck or the lane loading applied to a single laneon the basis of freely supported spans. It is indicated in the table whetherthe standard truck or the lane loading produces the maximum stress.

SECTION 5—Substructures and Retaining Walls

3. 5. 1.—Piles.

(a) General.

In general, piling shall be used when footings cannot, at a reasonableexpense, be founded on rock or other solid foundation material. At locations where unusual erosion may occur and the soil conditions permit thedriving of piles, they, preferably, shall be used as a protection againstscour, even though the safe bearing resistance of the natural soil is sufficientto support the structure without piling.

In general, the penetration for any pile shall be not less than 10 feetin hard material and not less than % the length of the pile nor less than20 feet in soft material.

For foundation work, no piling shall be used to penetrate a very softupper stratum overlying a hard stratum unless the piles penetrate the hardmaterial a sufficient distance to rigidly fix the ends.

(b) Limitation of Use.

Untreated timber piles may be used for temporary construction, revetments, fenders and similar work, and in permanent construction under thefollowing conditions:

(1) For foundation piling when the cutoff is below permanent ground

water level.

DESIGN 159

(b) For trestle construction when it is economical to do so, thoughtreated piles are preferable.

(3) They shall not be used where they will, or may be, exposed to marineborers.

The limitations of use of treated timber piles are given in division II,section 21.

(c) Design Loads.The design loads for piles shall be according to article 3. 4. 17.

Piles shall be designed to carry the entire superimposed load, no allowance being made for the supporting value of the material between the piles.

The supporting power of piles shall be determined by the applicationof test loads or by the use of formulas as specified in division II.

(d) Spacing, Clearances and Embedment.Footing areas shall be so proportioned that pile spacing shall be not

less than 2 feet 6 inches center to center. When the tops of foundationpiles are incorporated in a concrete footing, the distance from the sideof any pile to the nearest edge of the footing shall be not less than 9 inches.

The tops of piling in general shall project not less than 12 inches intothe concrete after all damaged material has been removed, but in specialcases it may be reduced to 6 inches.

(e) Batter Piles.When the lateral resistance of the soil surrounding the piles is inade

quate to counteract the horizontal forces transmitted to the foundation or

when increased rigidity of the entire structure is required, batter piles shallbe used in the foundation.

(f) Buoyancy.

The effect of hydrostatic; pressure shall be considered in the design as

provided in article 3. 2. 17.

(g) Concrete Piles (Precast).Precast concrete piles shall be of approved size and shape. If a square

section is employed, the corners shall be chamfered at least one inch. Piles,

preferably, shall be cast with a driving point and for hard driving, preferably, shall be shod with a metal shoe of approved pattern. Piling may be

either of uniform section or tapered. In general, tapered piling shall not

be used for trestle construction except for that portion of the pile whichlies below the ground line; nor shall tapered piles be used in any location

where the piles are to act as columns. In general, concrete piles shallhave a cross sectional area, measured above the taper, of not less than 140

square inches and when they are to be used in salt water they shall have

a cross sectional area of not less than 220 square inches.

The diameter of tapered piles measured 2 feet from the point shallbe not less than 8 inches. In all cases the diameter shall be considered as

the least dimension through the center. The point in all cases, where

steel points are not used, shall be not less than 6 inches in diameter and

the pile shall be beveled, tapered or sloped uniformly from the point to

2 feet from the point.Vertical reinforcement shall be provided consisting of not less than

four bars spaced uniformly around the perimeter of the pile. The verticalreinforcement shall be not less than 1 V2 per cent of the total cross section

measured above the taper, except that if more than four bars are used,

the number may be reduced to four in the bottom 4 feet of the pile.

160 HIGHWAY BRIDGES

The vertical steel shall be enclosed with spiral reinforcement for alength of 4 feet at each end of the pile and with either spiral reinforcement or hoops for the intervening portion. In lieu of spiral reinforcementequivalent hoops may be used in the ends of the pile.

The spiral reinforcing at the ends of the pile shall have a pitch of 3

inches, and gage of not less than No. 5 (Birmingham). In addition thetop 6 inches of pile shall have five turns of spiral winding at one-inch pitch.

For the remainder of the pile the vertical steel shall be enclosed withspiral reinforcing No. 5 gage (Birmingham), with not more than 6-inchpitch, or with %-inch round hoops spaced not more than 6-inch centers.

The reinforcement shall be placed at a clear distance from the face ofthe pile of not less than 2 inches and when the piles are for use in saltwater or alkali soils this clear distance shall be not less than 3 inches.

Stresses due to handling shall be considered in the design of the

reinforcement of long piles and extra reinforcement shall be added, ifnecessary. The stress in the steel shall note exceed 12,000 pounds per squareinch, allowing 100 per cent of the calculated load for impact and shock.

(h) Concrete Piles (Cast-in-Place).Cast-in-place concrete piles shall be, in general, cast in metal shells

which shall remain permanenty in place. However, other types of cast-in-place concrete piles, plain or reinforced, cased or uncased, may be usedif, in the opinion of the engineer, the soil conditions permit their use andif their design and the method of placing are satisfactory to him.

Cast-in-place concrete piles may be of either uniform section or tapered,or a combination thereof. The minimum size, measured at the butt, orabove the taper, and embedment of reinforcing shall be as specified forprecast piles, except that foundation piles may have a minimum butt cross-section area of 100 square inches. The minimum diameter at tip ofpile shall be 8 inches.

Cast-in-place piling shall be reinforced as prescribed for precast concrete piling to at least 10 feet below the plane at which the soil may be

considered firm. Where the encasement is in excess of .12 inches in thickness it may be considered as reinforcement subject to the deduction of Mg

inch for corrosion.Sufficient reinforcement shall be provided at the junction of the pile

with the superstructure to make a suitable connection.The metal shall be of sufficient thickness and strength so that the

shell will hold its original form and show no harmful distortion after itand adjacent shells have been driven and the driving core, if any, has been

withdrawn. The design of the shell shall be approved by the engineerbefore any driving is done.

(i) Steel Piles.

(1) Thickness of metal. Steel piles shall have a minimum thicknessof web of .400 inch. Splice plates shall be not less than % inch thick.

(2) Splices. Piles shall be spliced to develop the net section of pile.The flanges and web shall be either spliced by butt welding or with plates,welded, riveted or bolted. The bolted splices shall only be used on projectswhere a small number of piling are required and where facilities forriveting or welding are not available.

Splices shall be detailed on the contract plans.

(3) Caps. In general, caps are not required for steel piles embeddedin concrete. Reference is made to Research Report No. 1, 'Investigation

DESIGN 161

of the Strength of the Connection between a Concrete Cap and the Embedded end of the Steel H-Pile"—Department of Highways, State of Ohio,for a discussion of this subject and for the results of tests pertinent to it.

(4) If heavy scour is anticipated, consideration shall be given to design

of the portion of the pile which would be exposed, as a column.

(5) Lugs, scabs, and core-stoppers.

These devices may be used to increase the bearing power of the pilewhere necessary. They may consist of structural shapes, welded, rivetedor bolted, of plates welded between the flanges, or of timber or concreteblocks securely fastened.

(j) Steel Pile and Steel Pile Shell Protection.

Where conditions of exposure warrant, concrete encasement shall be

used on steel piles and steel pile shells. The encasement shall extendbetween an elevation 2 feet below the ground or low water surface andnot less than two feet above the ground or ordinary water level.

3. 5. 2.—Footings.

(a) Depth.The depths of footings shall be determined with respect to the character

of the foundation materials and the possibility of undermining. Exceptwhere solid rock is encountered or in other special cases, the footings of allstructures, other than culverts, which are exposed to the erosive action ofstream currents, preferably, shall be founded at a depth of not less than

4 feet below the permanent bed of the stream. Stream piers and archabutments, preferably, shall be founded at a depth of not less than 6 feetbelow stream bed. The above preferred minimum depths shall be increasedas conditions may require.

Footings not exposed to the action of stream currents shall be foundedon a firm foundation and below frost.

Footings for culverts shall be carried to an elevation sufficient to securea firm foundation, or a heavy reinforced floor shall be used to distributethe pressure over the entire horizontal area of the structure. In any

location liable to erosion, aprons or cut-off walls shall be used at both ends

of the culvert and, where necessary, the entire floor area between the

wing walls shall be paved. Baffle walls or struts across the unpaved bottomof a culvert barrel shall not be used where the stream bed is subject to

erosion. When conditions require, culvert footings shall be reinforcedlongitudinally.

(b) Anchorage.Footings on inclined smooth solid rock surfaces which are not restrained

by an overburden of resistant material, shall be effectively anchored by

means of anchor bolts, dowels, keys or other suitable means.

(c) Distribution of Pressure.

All footings shall be designed to keep the maximum soil pressures

within safe bearing values. In order to prevent unequal settlement, footingsshall be designed to keep the pressure as nearly uniform as practicable.

In footings having unequal pressures and requiring piling, the spacing of

the piles shall be such as to secure as nearly equal loads on each pile as

may be practicable.

162 HIGHWAY BRIDGES

fd) Spread Footings.Spread footings which act as cantilevers may be decreased in thickness

from the junction of the footing slab with column or wall toward the edge

of the footing, provided sufficient section is maintained at all points toprovide the necessary resistance to diagonal tension and bending stresses.This decrease in section may be accomplished by sloping the upper surfaceof the footing or by means of vertical steps. Stepped footings shall becast monolithically.

Except in small structures, no footing shall have a thickness at theedge of less than 2 feet. When piles are used, the footing shall have anedge thickness of not less than 18 inches above the tops of the piles.

(e) Internal Stresses in Spread Footings.

Spread footings shall be considered as under the action of downwardforces, due to the superimposed loads, resisted by an upward pressureexerted by the foundation materials and distributed over the area of thefootings as determined by the eccentricity of the resultant of the downwardforces. Where piles are used under footings, the upward reaction of thefoundation shall be considered as a series of concentrated loads applied atthe pile centers, each pile being assumed to carry its computed proportionof the total footing load.

When a single spread footing supports a column, pier or wall, thisfooting shall be assumed to act as a cantilever. When two or more piersor columns are placed upon a common footing, the footing slab shall bedesigned for the actual conditions of continuity and restraint.

Footings shall be designed for the bending stress, diagonal tensionstress and bond at the critical section designated herein.

The critical section for bending shall be taken at the face of the column,pedestal or wall. In the case of columns other than square or rectangular,the critical section shall be taken at the side of the concentric square ofequivalent area. For footings under masonry walls, where bond betweenthe wall and footing is reduced to friction value, the critical section shallbe taken as midway between the middle and the face of the wall. For footings under metallic column bases, the critical section shall be taken asmidway between the face of the column and the edge of the metallic base.The load shall be considered as uniformly distributed over the column,pedestal or wall, or metallic column base.

The critical section for bond shall be taken at the same plane as forbending, and the shear used for computing bond shall be based on the sameloading and section as for bending. Bond should also be investigated atplanes where changes of section or of reinforcement occur.

The critical section for diagonal tension in footings on soil or rockshall be considered as the concentric vertical section through the footingat a distance d from each face of the column, pedestal, or wall; d beingequal to the depth from the top of the section to the centroid of the longitudinal tension reinforcement.

The critical section for diagonal tension in footings supported on pilesshall be considered as the concentric vertical section through the footingat a distance d/2 from each face of the column, pedestal or wall, and anypiles considered in computing the diagonal tension.

In sloped or stepped footings, stresses should be investigated at sec

tions where the depth changes outside the critical section as defined above.Bending need not be considered unless the projection of the footing is

more than two-thirds of the depth.

DESIGN 168

In plain concrete footings, the stresses shall be computed on the basisof a monolithic section having a depth measured from the top of the footingto a plane 2 inches above the bottom of the footing. The maximum fibrestress due to bending shall not exceed that specified in article 3. 4. 11 andthe average shearing stress on a concentric vertical section through thefooting at a distance (d minus 2 inches) from each face of the column,pedestal or wall, shall not exceed the shearing stresses specified in article3. 4. 11 for beams without web reinforcement and with longitudinal barsnot anchored.

(f) Reinforcement.Footing slabs shall be reinforced for bending stresses and, where

necessary, for diagonal tension. All bars shall be effectively anchored todevelop in bond the computed stress in the bar.

The reinforcement for square footings shall consist of two or morebands of bars. The reinforcement necessary to resist the bending momentin each direction in the footing shall be determined as for a reinforcedconcrete beam; the effective depth of the footing shall be the depth fromthe top to the plane of the reinforcement. The required reinforcementshall be spaced uniformly across the footing, unless the footing width isgreater than the side of the column or pedestal plus twice the effectivedepth of the footing, in which case the width over which the reinforcementis spread may equal the width of the column or pedestal plus twice theeffective depth of the footing plus one-half the remaining width of thefooting. In order that no considerable area of the footing shall remainunreinforced, additional bars shall be placed outside of the width specified,but such bars shall not be considered as effective in resisting the calculatedbending moment. For the extra bars a spacing double that used for thereinforcement within the effective belt may be used. When reinforcementis used in more than one direction the allowable unit bond stresses shallbe reduced as follows :

For two-way reinforcement . .

For each additional direction

(g) Transfer of Stress from Vertical Reinforcement.The stresses in the vertical reinforcement of columns or walls shall be

transferred to the footings by extending the reinforcement into them a

sufficient distance to develop the strength of the bars in bond, or by meansof dowels anchored in the footings and overlapping or fastened to thevertical bars in such manner as to develop their strength. If the dimensionsof the footings are not sufficient to permit the use of straight bars, thebars may be hooked or otherwise mechanically anchored in the footings.

3. S. 3.—Abutments,

(a) General.

Abutments shall be designed to withstand earth pressure as specifiedin article 3. 2. 18, the weight of abutment and superstructure, live load overany portion of the superstructure or approach fill, wind forces, longitudinalforce when the bearings are fixed, and longitudinal forces due to frictionalbearings. The design shall be investigated for any combination of theseforces which may produce the most severe condition of loading.

Abutments shall be designed to be safe against overturning about thetoe of the footing, against sliding on the footing base and against crushing

2o per cent10 per cent

164 HIGHWAY BRIDGES

of foundation material or overloading of piles at the point of maximumpressure.

In computing stresses in abutments, the weight of filling materialdirectly over an inclined or stepped rear face, or over a reinforced concretespread footing extending back from the face wall, may be considered as

part of the effective weight of the abutment. In the case of a spreadfooting, the rear projection shall be designed as a cantilever supported atthe abutment stem and loaded with the full weight of the superimposedmaterial, unless a more exact method is used.

The cross section of stone masonry or plain concrete abutments shall be

proportioned to avoid the introduction of tensile stress in the material.

(b) Reinforcement for Temperature.

Except in gravity abutments, not less than % square inch of horizontalreinforcement per foot of height shall be provided near exposed surfacesnot otherwise reinforced, to resist the formation of temperature and shrinkage cracks.

(c) Wing Walls.

Wing walls shall be of sufficient length to retain the roadway embankment to the required extent and to furnish protection against erosion.For ordinary materials, in the absence of accurate data, the slope of thefill shall be assumed as 1% horizontal to one vertical and wing lengthscomputed on this basis.

Reinforcing rods or other suitable rolled sections, preferably, shallbe spaced across the junction between all wing walls and abutments tothoroughly tie them together. Such bars shall extend into the masonry oneach side of the joint far enough to develop the strength of the bar as

specified for bar reinforcement, and shall vary in length so as to avoidplanes of weakness in the concrete at their ends. If bars are not used, an

expansion joint shall be provided at this point in which the wings shall be

mortised into the body of the abutment.

(d) Drainage.

The filling material behind abutments shall be effectively drained byweep holes with French drains, placed at suitable intervals.

3. 5. 4.—Retaining Walls.

(a) General.

Retaining walls shall be designed to withstand earth pressure, including any live load surcharge, and the weight of the wall, in accordancewith the general principles specified above for abutments.

Stone masonry and plain concrete walls shall be of the gravity type.Reinforced concrete walls may be of either the cantilever, counterforted,buttressed, or cellular types.

(b) Base or Footing Slabs.

The rear projection or heel of base slabs shall be designed to supportthe entire weight of the superimposed materials, unless a more exactmethod is used.

The base slabs of cantilever walls shall be designed as cantileverssupported by the wall.

The base slabs of counterforted and buttressed walls shall be designed

DESIGN 165

as fixed or continuous beams of spans equal to the distance between counterforts or buttresses.

(c) Vertical Walls.

The vertical stems of cantilever walls shall be designed as cantileverssupported at the base.

The vertical or face walls of counterforted and buttressed walls shallbe designed as fixed or continuous beams. The face walls shall be securelyanchored to the supporting counterforts or buttresses by means of adequatereinforcement.

(d) Counterforts and Buttresses.

Counterforts shall be designed as T-beams. Buttresses shall be designed as rectangular beams. In connection with the main tension reinforcement of counterforts there shall be a system of horizontal and verticalbars or stirrups to effectively anchor the face walls and base slab. Thesestirrups shall be anchored as near the outside faces of the face walls, andas near the bottom of the base slab as practicable.

(e) Reinforcement for Temperature.Except in gravity walls, not less than % square inch of horizontal

reinforcement per foot of height shall be provided near exposed surfacesnot otherwise reinforced, to resist the formation of temperature andshrinkage cracks.

(f) Expansion and Contraction Joints.Contraction joints shall be provided at intervals not exceeding 30 feet

and expansion joints at intervals not exceeding 90 feet, for gravity or reinforced concrete walls.

(g) Drainage.

The filling material behind all retaining walls shall be effectivelydrained by weep holes with French drains, placed at suitable intervals. Incounterforted walls there shall be at least one drain for each pocket formedby the counterforts.

3. 5. 5.—Piers.

(a) General.Piers shall be designed to withstand the dead and live loads super-

Imposed thereon; wind pressures acting on the pier and superstructure;the forces due to stream current, floating ice and drift; and longitudinalforces at the fixed ends of spans.

Where necessary, piers shall be protected against abrasion by facingthem with granite, vitrified brick, timber or other suitable material withinthe limits of damage by floating ice or debris.

(b) Pier Nose.In streams carrying ice or drift, the pier nose shall be designed as

an ice breaker. When a steel angle or other metal nosing is used it shallbe effectively secured to the masonry by means of suitable anchors.

3. 5. 6.—Tubular Steel Piers,

(a) Use.Preferably, tubular steel piers shall not be used and they shall never

be used in locations where they will be subjected to lateral earth pressure.

166 HIGHWAY BRIDGES

In special cases their use may be permitted, in which cases the followingrequirements shall apply:

(b) Depth.

The general requirements governing the depths of foundations as aboveset forth shall govern in the case of tubular steel piers except that steeltubes resting upon gravel foundation without piling shall in no case be

carried to a depth less than 8 feet below the permanent bed of the streamand to such additional depth as may be necessary to eliminate all dangerof undermining.

(c) Piling.

Piles used in connection with tubular piers shall extend into theconcrete filling a sufficient distance to thoroughly brace the tubes. Ingeneral, these piles shall extend not less than 6 to 8 feet above the bottomof the concrete.

(d) Dimensions of Shell.

The minimum thickness of the metal in the shells of tubular piers shallbe %e inch. This thickness shall be increased where necessary to securestrength and rigidity for placing the shell. In all cases the pier shall be

designed for safe pile or soil bearing values as specified herein, but whenthe diameter required by these values is greater than that required for thesuperstructure bearing, the diameter may be reduced at any splice point.The minimum diameter of steel cylinders used for piers shall be 42 inches.

(e) Splices and Joints.All horizontal joints shall be butt joints. Vertical joints may be

lapped if the corners of the plates are properly scarfed. When fieldsplicing is necessary the lower section of the tube shall extend at least 2 feetabove the water line when in position.

(f) Bracing.Adequate bracing connecting the tubes of cylinder piers shall be pro

vided. In general, this bracing shall consist of a steel or concrete girderdiaphragm effectively secured to the tubes. The depth of this diaphragmshall be as great as conditions will permit.

SECTION 6—Structural Steel Design

3. 6. 1.—Number of Trusses or Girders.

Preferably, through spans shall have only two trusses, arches or girders.

3. 6. 2.—Spacing of Trusses and Girders.

Main trusses, arches and girders shall be spaced a sufficient distanceapart center to center, to be secure against overturning by the assumedlateral forces.

3. 6. 3.—Effective Span.

For the calculation of stresses, span lengths shall be assumed asfollows :

Beams and girders, distance between centers of bearings.Trusses, distance between centers of end pins or of bearings.Floorbeams, distance between centers of trusses or girders.Stringers, distance between centers of floorbeams.

DESIGN 16?

3. 6. 4.—Effective Depth.

For the calculation of stresses, effective depths shall be assumed asfollows:

Riveted trusses, distance between centers of gravity of the chords.Pin-connected trusses, distance between centers of chord pins.

Plate girders, distance between centers of gravity of the flanges, butnot to exceed the distance back to back of flange angles.

3. 6. S.—Alternating Stresses.

Members subject to alternating stresses of tension and compression,due to the combination of dead, live, impact and centrifugal stresses, shallbe proportioned for the kind of stress requiring the larger section.

If the alternating stresses occur in succession during one passage ofthe live load, each shall be increased by 5,0 per cent of the smaller. Theconnections of such members shall be proportioned for the sum of the netalternating stresses not so increased.

If the live load and dead load stresses are of opposite sign, only 70 percent of the dead load stress shall be considered as effective in counteractingthe live load stress.

3. 6. 6.—Combined Stresses.

All members subject to combined bending and direct stresses shall beproportioned for the maximum unit stress specified in appendix "B." Whenbending stresses are induced by the component of externally applied loadsacting perpendicular to the axis of the member, a shall be assumed equalto + 1.

3. 6. 7.—Secondary Stresses.

The design and details shall be such that secondary stresses will be

as small as practicable. Secondary stresses due to truss distortion or floor-beam deflection usually need not be considered in any member the widthof which, measured parallel to the plane of distortion, is less than one-tenthof its length. If the secondary stress exceeds 4,000 pounds per squareinch for tension members and 3,000 for compression members, the excessshall be treated as a primary stress.

3. 6. 8.—Rolled Beams.

Rolled beams shall be proportioned by the moments of inertia method oftheir net sections.

Suitable stiffeners shall be provided to stiffen the webs of rolled beamsat bearings, when the unit shear in the web adjacent to the bearing exceeds75 per cent of the allowable shear for girder webs.

The compression flanges of rolled beams or stringers supporting timberfloors shall not be considered to be laterally supported by the flooring unlessthe floor and fastenings are specially designed to provide adequate support.

3. 6. 9.—Limiting Lengths of Members.

For compression members, the greatest ratio of unsupported length toradius of gyration shall not exceed 120 for main members, or those inwhich the major stresses result from dead or live load, or both; and shallnot exceed 140 for secondary members, or those whose primary purpose isto brace the structure against lateral or longitudinal forces, or to brace orreduce the unsupported length of other members, main or secondary.

168 HIGHWAY BRIDGES

In determining the radius of gyration, the area of any portion of amember may be neglected, provided that the area thus neglected shall notbe used in calculating the strength of the member. For members resistingcalculated compressive stress, all of the specified requirements for minimumthickness of component parts to resist bucking shall apply to materialcomprising any area thus neglected.

The radius of gyration and the effective area for carrying stress of a

member containing perforated cover plates shall be computed for a transverse section through the maximum width of perforation. When perforations are staggered in opposite cover plates the cross-sectional area of themember shall be considered the same as for a section having perforations inthe same transverse plane.

Unsupported length shall be assumed as follows: For the top chordsof half -through trusses, the length between panel points laterally supportedas required under 3. 6. 70 ; for other main members, the length betweenpanel point intersections or centers of braced points or centers of endconnections; for secondary members, the length between the centers of theend connections of such member or centers of braced points.

For tension members, except rods, eyebars, cables, and plates, thegreatest ratio of unsupported length to radius of gyration shall not exceed

200 for main members, and shall not exceed 240 for bracing members.

3. 6. 10.—Deflection.

The term "deflection" as used herein shall be the deflection computedin accordance with the assumptions made for loading when computing thestress in the member.

Steel beams or girders having simple or continuous spans shall bedesigned so that the deflection due to live load plus impact shall not exceed

%oo of the span, the span length being considered the distance center tocenter of bearings.

The deflection of cantilever arms due to live load plus impact shall be

limited to ^oo of the cantilever arm.

When bridges have cross bracing or diaphragms sufficient in depthand strength to insure lateral distribution of loads, the deflection may be

computed for the standard loading, considering all beams or girders asacting together and having equal deflection.

Sidewalk live load may be neglected in computing deflection.

The moment of inertia of the gross cross-sectional area shall be usedfor computing the deflections of beams and girders.

The gross area of each member shall be used in computing the deflectionsof trusses. When perforated cover plates are used in truss members, theeffective area shall be the net volume divided by the length from centerto center of perforations.

3. 6. 11.—Depth Ratios.

The ratio of the depth to the length of spans, preferably shall be notless than the following:

For trusses 1/10For plate girders and rolled beams used as girders 1/25For continuous spans, the span length shall be considered

as the distance between dead load points of contraflexure.

DESIGN 169

If depths less than these are used, the sections shall be so increasedthat the maximum deflection will be not greater than if these ratios had notbeen exceeded.

3. 6. 12.—Symmetrical Sections.

Main members shall be proportioned so that their gravity axes willbe as nearly as practicable in the center of the section.

3. 6. 13.—Effective Area of Angles in Tension.

The effective area of a single angle tension member, or of each angleof a double tension member in which the angles are connected back to backon the same side of a gusset plate, shall be assumed as the net area of theconnected leg plus one-half of the area of the unconnected leg.

If a double angle tension member is connected with the angles back toback on opposite sides of a gusset plate, the full net area of the anglesshall be considered as effective. If the angles connect the separate gussetplates, as in the case of a double-webbed truss, and the angles are connectedby stay plates located as near the gussets as practicable, or by othereffective means, the full net area of the angles shall be considered aseffective. If the angles are not so connected, only 80 per cent of the netarea shall be considered as effective.

Lug angles may be considered as effective in transmitting stress,provided they are connected with at least one-third more rivets than requiredby the stress to be carried by the lug angle.

3. 6. 14.—Thickness of Metal.

Gusset plates for main members shall not be less than % inch inthickness. Other structural steel, except for webs of rolled shapes, fillers,and in railings, shall be not less than inch in thickness. The web thickness of rolled shapes shall not be less than 0.23 inch. Silicon steel platesshall be not more than 1% inches thick, low-alloy steel plates not morethan 1% inches thick and nickel steel plates not more than 1 inch in thickness.

Metal exposed to marked corrosive influences shall be increased inthickness or specially protected against corrosion.

3. 6. 15.—Compression Members.

Compression members shall be so designed that the main elements ofthe section will be connected directly to the gusset plates, pins, or othermembers.

The center of gravity of a built-up section shall coincide as nearly as

practicable with the center of the section. Preferably the segments shallbe connected by solid webs.

In members consisting of segments connected by cover plates or lacing,or segments connected by webs, the thickness of the webs of the segmentsshall be not less than %2 of the unsupported distance between the nearestrivet lines or the roots of flanges of rolled segments for carbon steel,

for silicon steel, %e for low-alloy steel or ^5 for nickel steel.

The thickness of cover plates or webs connecting the segments shall be

not less than y±o of the unsupported distance between the nearest lines oftheir connecting rivets or the roots of their rolled flanges for carbon steel, %efor silicon steel, %4 for low-alloy steel or Vs2 for nickel steel.

170 HIGHWAY BRIDGES

3. 6. 16 Web Plates of Solid Rib Arches.

The thickness of web plates in solid rib arches shall not be less than thefollowing fractions of the depth as defined in article 3. 6. 15, except thatwhen the web is reinforced along its axis with a longitudinal rib of amplecross-sectional area and rigidity, the thickness shall not be less than one-halfof these amounts:

Vtto for carbon steel.%o for silicon steel.Vi8 for low-alloy steel.Vis for nickel steel.

3. 6. 17.—Outstanding Legs of Angles and Bearing Sliffeners.The widths of outstanding legs of angles in compression (except where

reinforced by plates) shall not exceed the following:In girder flanges and bearing stiffeners, 12 times the thickness.In main members carrying axial stress, 12 times the thickness.In bracing and other secondary members, 16 times the thickness.

3. 6. 18 Size of Pins.

Pins shall be proportioned for the maximum shears and bending moments produced by the stresses in the members connected. If there areeyebars among the parts connected, the diameter of the pin shall be notless than 0.8 of the width of the widest bar.

Details of Design

3. 6. 19.—Size of Rivets.

Rivets shall be of the size shown on the drawings, but generally shallbe % inch or % inch in diameter. Rivets % inch in diameter shall not be

used in members carrying calculated stress except in 2% -inch legs of anglesand in flanges of sections requiring % rivets.

The diameter of rivets in angles carrying calculated stress shall notexceed one-fourth of the width of the leg in which they are driven.

In angles whose size is not determined by calculated stress, %-inchrivets may be used in 2-inch legs, %-inch rivets in 2 %-inch legs, %-inchrivets in 3-inch legs, and 1-inch rivets in 3 %-inch legs.

Structural shapes which do not admit the use of %-inch diameter rivetsshall not be used except in handrails.

3. 6. 20.—Pitch of Rivets.

The minimum distance between centers of rivets shall be three timesthe diameter of the rivet but, preferably, shall be not less than thefollowing:

For 1-inch rivets, 3% inches.For %-inch rivets, 3 inches.For %-inch rivets, 2% inches.For %-inch rivets, 2% inches.

3. 6. 21.—Pitch in Ends of Compression Members.

In the ends of compression members the pitch of rivets connecting thecomponent parts of the member shall not exceed four times the diameter ofthe rivet for a length equal to 1% times the maximum width of the member.Beyond this point the pitch shall be increased gradually for a length equal

DESIGN 171

to \V» times the maximum width ef the member until the maximum pitchis reached.

3. 6. 22.—Maximum Pitch.

The maximum pitch in the line of stress shall not exceed 6 inches or16 times the thickness of the thinnest outside plate or angle connected,except that in angles having two gauge lines with the rivets staggered,the pitch in each line may be twice that given by these rules, with amaximum of 10 inches.

3. 6. 23.—Stitch Riveu.

If two or more plates or shapes are in contact, they shall be heldtogether by stitch rivets. In compression members, the stitch rivets shallbe spaced on a gage line, in the direction perpendicular to the line of stressnot more than 24 times the thickness of the thinnest plate, and, in the lineof stress, not more than 12 times the thickness of the thinnest outer plate.In tension members and girders, the stitch rivets shall be spaced, on apitch, not more than 24 times the thickness of the thinnest outer plate. Intension members composed of two angles in contact, the angles shall be heldtogether by stitch rivets having a maximum pitch of 12 inches.

3. 6. 24.—Edge Distance of Rivets.

The minimum distance from the center of any rivet to a sheared edgeshall be:

For 1-inch rivets, 1 % inches.For %-inch rivets, 1% inches.For %-inch rivets, 1% inches.For %-inch rivets, 1% inches.

The minimum distance from a rolled or planed edge, except in flangesof beams and channels, shall be:

For 1-inch rivets, 1% inches.For %-inch rivets, 1% inches.For %-inch rivets, 1% inches.For %-inch rivets, 1 inch.

The maximum distance from any edge shall be eight times the thickness of the thinnest outside plate, but shall not exceed 5 inches.

3. 6. 25.—Long Rivets.

Rivets subjected to calculated stress and having a grip in excess of4% diameters shall be increased in number at least 1 per cent for eachadditional Me inch of grip. If the grip exceeds six times the diameter ofthe rivet, specially designed rivets shall be used.

3. 6. 26.—Rivets in Tension.

Rivets in direct tension shall, in general, not be used, but if so usedtheir value shall be one-half that permitted for rivets in shear. Countersunk rivets shall not be used in tension.

3. 6. 27.—Parts Accessible.

The accessibility of all parts of a structure for inspection, cleaningand painting shall be secured by the proper proportioning of members andthe design of their details.

172 HIGHWAY BRIDGES

3. 6. 28.—Closed Sections and Pockets.

Closed sections, and pockets or depressions which will retain water,shall be avoided so far as practicable. Pockets shall be provided witheffective drain holes or be filled with waterproofing material.

Details shall be so arranged that the retention of dirt, leaves, andother foreign matter will be reduced to a minimum. Wherever angles areused, either singly or in pairs, preferably they shall be placed with thevertical legs extending downward.

3. 6. 29.—Eccentric Connections.

Members, including bracing, shall be so connected that their gravityaxes will intersect in a point. Eccentric connections shall be avoided ifpracticable, but if unavoidable the members shall be so proportioned thatthe combined fiber stresses will not exceed the allowed axial stress.

3. 6. 30.—Strength of Connections.

Except as otherwise provided herein, connections shall be designed forthe average of the calculated stress and the strength of the member, butthey shall be designed for not less than 75 per cent of the strength of themember.

Connections shall be made symmetrical about the axes of the membersin so far as practicable. Connections, except for lacing bars and handrails, shall contain not less than three rivets.

3. 6. 31.—Splices.

Compression members, such as chords and trestle columns, in rivetedstructures shall have milled ends and full contact bearing at the splices.

Splices, whether in tension, compression, bending or shear, shall bedesigned for the average of the calculated stress and the strength of themember, or section, but they shall be designed to transmit through the splicematerial not less than 75 per cent of the strength of the member. The spliceshall be as near a panel point as practicable.

Splices in riveted columns and chord members shall be located as closeto panel points as possible and, usually, shall be on that side of the panelpoint where the smaller stress occurs.

The arrangement of the plates, angles and other splice elements shallbe such as to make proper provision for the stresses, both axial and bendingsin the component parts of the members spliced.

3. 6. 32.—Indirect Splices.

If splice plates are not in direct contact with the parts which theyconnect, the number of rivets on each side of the joint shall be in excessof the number required for a direct-contact splice to the extent of twoextra transverse lines of rivets for each intervening plate.

3. 6. 33 FUler:

(a) Welding.When welding is called for on the plans it shall be designed according

to specifications of the American Welding Society, "Welded Highway andRailway Bridges."

(b) Riveting.If rivets carrying stress pass through fillers, the fillers, preferably shall

be extended beyond the connected member, and the extension secured by

DESIGN 173

enough additional rivets to average the total stress in the member over thecombined area of the member plus the fillers. As an alternate, the additionalrivets may be passed through the connected members without extending thefiller.

If the filler is less than %-inch thick it shall not be extended beyondthe splicing material and additional rivets are not required. Fillers %-inchor more in thickness shall consist of not more than two plates, unless specialpermission is given by the engineer.

3. 6. 34.—Gusset Plates.Gusset or connecting plates shall be used for connecting main members,

except when they are pin-connected. The rivets connecting each membershall be symmetrical with the axis of the member, so far as practicable,and the full development of the elements of the member shall be givenconsideration. The gusset plates shall be of ample thickness to resist shear,direct stress, and flexure, acting on the weakest or critical section ofmaximum stress.

Re-entrant cuts, except curves made for appearance, shall be avoidedas far as practicable.

If the unsupported edge of a gusset plate exceeds the following numberof times its thickness, the edge shall be stiffened:

60 for carbon steel.50 for silicon steel.48 for low-alloy steel.45 for nickel steel.

3. 6. 35.—Stay Plates.The open sides of compression members shall be provided with lacing

bars and shall have stay plates as near each end as practicable. Stayplates shall be provided at intermediate points where the lacing is interrupted. In main members, the length of the end stay plates between endrivets shall be not less than 1% times the distance between the inner linesof rivets connecting them to the flanges; and the length of intermediatestay plates between end rivets, not less than % of that distance. In lateralstruts and other secondary members, the over-all length of end and intermediate stay plates shall be not less than % of the distance between theinner lines of rivets connecting them to the flanges.

The separate segments of tension members composed of shapes may beconnected by stay plates or end stay plates and lacing. End stay platesshall have the same minimum length as specified for end stay plates onmain compression members and intermediate stay plates shall have a

minimum length of % of that specified for intermediate stay plates on maincompression members. The clear distance between stay plates on tensionmembers shall not exceed 3 feet.

The thickness of stay plates shall be not less than Yso of the distancebetween the inner lines of rivets connecting them to the flanges for mainmembers, or Yeo of that distance for bracing members. Stay plates shallbe connected by not less than three rivets on each side, and in membershaving lacing bars the last rivet in the stay plate, preferably shall alsopass through the end of the adjacent bar.

When perforated cover plates are used instead of lacing bars and stayplates, refer to article 3. 6. 36, item "Perforated Cover Plates."

3. 6. 36. —Lacing and Perforated Cover Plates.

Lacing bars of compression members shall be so spaced that the slender-ness ratio of the portion of the flange included between the lacing bar

174 HIGHWAY BR1DGES

connections will be not more than 40 nor more than two-thirds of theslenderness ratio of the member.

In compression members, the shearing stress normal to the member inthe plane of the lacing or perforations shall be that obtained by the following formulas : /

V = normal shearing stress in pounds.P = allowable compressive axial load on members.L = length of member in inches.r = radius of gyration of section about the axis perpendicular to

plane of lacing in inches.

To the shear so determined shall be added any shear due to the weightof the member or to other forces, and the lacing proportioned for thecombined shear.

The shear shall be considered as divided equally among all parallelplanes in which there are shear-resisting elements, whether continuousplates or lacing. The section of the lacing bars shall be determined by theformula for axial compression in which L is taken as the distance alongthe bar between its connections to the main segments for single lacing and70 per cent of that distance for double lacing.

If the distance across the member between the rivet lines in the flangesis more than 15 inches and a bar with a single rivet in the connection isused, the lacing shall be double and riveted at the intersections.

The angle between the lacing bars and the aiis of the member shall be

approximately 45 degrees for double lacing and^0

degrees for single lacing.Lacing bars may be shapes or flat bars. For main members the

minimum thickness of flat bars shall be ViO of the distance along the barbetween its connections for single lacing and %o for double lacing. Forbracing members the limits shall be %o for single lacing and Vis for doublelacing.

The diameter of rivets in lacing bars shall not exceed one-third of thewidth of the bar. There shall be at least two rivets in each end of lacingbars riveted to flanges more than 5 inches in width.

Perforated Cover Plates.

When perforated cover plates are used instead of lacing bars and stayplates, the following provisions shall govern their design:

For structural carbon steel,

For structural

DESIGN 175

(1) The thickness of cover plate shall not be less than vaa of the unsupported distance between the nearest lines of connecting rivets for carbonsteel, Va for silicon steel, %2 for low-alloy steel and Vio for nickel steel.

(2) The transverse distance from the perforation to the nearest line ofconnecting rivets or point of support shall not exceed twelve (12) timesthe thickness of plate when measured at the centerline of perforation.

(3) The ratio of length (in the direction of stress) to width of perforation shall not exceed two.

(4) The clear distance between perforations, in the direction of stress,shall not be less than the unsupported distance between the nearest linesof connecting rivets.

(5) The clear distance between the end perforation and the end of thecover plate shall not be less than 1.25 times the unsupported distance betweenthe nearest lines of connecting rivets in the cover plate.

(6) The periphery of the perforation at all points shall have a minimum radius of 1% inches.

3. 6. 37.—Net Section at Pin Holes.

In pin-connected tension members the net section across the pin holeshall be not less than 140 per cent and the net section back of the pin hole notless than 100 per cent of the net section of the body of the member. Theratio of the net width (through the pin hole transverse to the axis of the

member) to the thickness of the segment shall not be more than 8.

3. 6. 38.—Net Section of Riveted Tension Members.

The net section of a riveted tension member is the sum of the netsections of its component parts. The net section of a part is the productof the thickness of the part multiplied by its least net width.

The net width for any chain of holes extending progressively acrossthe part shall be obtained by deducting from the gross width the sum ofthe diameters of all the holes in the chain and adding, for each gage spacein the chain, the quantity:

J!4g

where S = pitch of any two successive holes in the chaing = gage of the same holes.

The net section of the part is obtained from the chain which give?the least net width.

For angles, the gross width shall be the sum of the widths of the legsless the thickness. The gage for holes in opposite legs shall be the sumof gages from back of angle less the thickness.

For splice members, the thickness shall be only that part of the thickness of the member which has been developed by rivets beyond the sectionconsidered.

The diameter of the hole shall be taken as % inch greater than thenominal diameter of the rivet.

3. 6. 39.—Location of Pins.

Pins shall be so located with respect to the gravity axes of the membersas to reduce to a minimum stresses due to bending.

176 HIGHWAY BRIDGES

3. 6. 40.—Pin Plates.

When necessary for the required section or bearing area, the sectionat the pin holes shall be increased on each segment by plates so arrangedas to reduce to a minimum the eccentricity of the segment. One plate oneach side shall be as wide as the outstanding flanges will allow. At leastone full width plate on each segment shall extend to the far edge of thestay plate and the others not less than 6 inches beyond the near edge.

These plates shall be connected by enough rivets to transmit the bearingpressure and so arranged as to distribute it uniformly over the full section.

3. 6. 41.—Forked Ends.

Forked ends will be permitted only where unavoidable. There shall beenough pin plates on forked ends to make the section of each jaw equal tothat of the member. The pin plates shall be long enough to develop thepin plate beyond the near edge of the stay plate, but not less than thelength required by article 3. 6. 40.

3. 6. 42.—Pins and Pin Nuts.

Pins shall be of sufficient length to secure a full bearing of all partsconnected upon the turned body of the pin. They shall be secured inposition by hexagonal recessed nuts or by hexagonal solid nuts with washers.If the pins are bored, through rods with cap washers may be used. Pinnuts shall be malleable castings or steel. They shall be secured by cotterpins in the screw ends or else the screw ends shall be long enough to

permit burring the threads.

Members shall be held against lateral movement on the pins.

3. 6. 43.—Bolts.

Bolted connections shall not be used unless specifically authorized.Bolts shall be unfinished; turned as specified and meeting the requirementsof division IV ; or an approved form of ribbed bolt.

Bolts in tension shall have single self-locking nuts or double nuts.

3. 6. 44.—Upset Ends.

Bars and rods with screw ends shall be upset to provide a section atthe root of the thread, which will exceed the net section of the body of themember by at least 15 per cent.

3. 6. 45.—Sleeve Nuts.

Sleeve nuts shall not be used.

3. 6. 46.—Expansion and Contraction.

The design shall be such as to allow for expansion and contraction atthe rate of 1% inches in 100 feet. Provision shall be made for changes inlength of span resulting from live load stresses. In spans more than 300

feet long, allowance shall be made for expansion and contraction in thefloor. The expansion end shall be secured against lateral movement.

3. 6. 47.—Expansion Bearings.

Spans of less than 70 feet may be arranged to slide upon metal plateswith smooth surfaces. Spans of 70 feet and greater shall be provided withrollers or rockers.

DESIGN 177

3. 6. 48.—Bronze or Copper Alloy Sliding Expansion Bearings.

Bronze or copper alloy sliding plates shall be chamfered at the ends.They shall be held securely in position, usually by being inset into the metalof the pedestals and sole plates. Provision shall be made against anyaccumulation of dirt which will obstruct free movement of the span.

3. 6. 49.—Fixed Bearings.

Fixed ends shall be firmly anchored.

3. 6. 50.—Pedestals and Shoes.

Pedestals and shoes, preferably, shall be made of cast steel or structural steel. The difference in width between the top and bottom bearingsurfaces shall not exceed twice the distance between them. For hingedbearings, this distance shall be measured from the center of the pin. Inbuilt pedestals and shoes, the web plates and angles connecting them tothe base plate shall be not less than % inch thick. If the size of thepedestal permits, the webs shall be rigidly connected transversely. Theminimum thickness of the metal in cast steel pedestal shall be 1 inch.Pedestals and shoes shall be so designed that the load will be distributeduniformly over the entire bearing. Spans of 70 feet and greater shall havehinged or pin bearings at both ends.

3. 6. 51.—Rollers.

Expansion rollers shall be not less than 6 inches in diameter. Theyshall be connected by substantial side bars and shall be guided by gearingor other effectual means to prevent lateral movement, skewing and creeping. The rollers and bearing plates shall be protected from dirt and wateras far as practicable, and the design shall be such that water will not be

retained and that the roller nests may be inspected and cleaned easily.

3. 6. 52.—Inclined Bearings.

For spans on an inclined grade and without hinged bearings, the soleplates shall be beveled so that the masonry surfaces and the slidingsurfaces will be level.

3. 6. 53.—Anchor Bolts.

Trusses, girders and I-beam spans shall be securely anchored to thesubstructure. Anchor bolts shall be swedged or threaded to secure a satisfactory grip upon the material used to embed them in the holes.

The following are the minimum requirements for each bearing:

For I-beam spans the outer beams shall be anchored at each endwith 2 bolts, 1 inch in diameter, set 10 inches in the masonry.

For trusses and girders:Spans 50 feet in length or less, 2 bolts, 1 inch in diameter, set

10 inches in the masonry.Spans 51 to 100 feet, 2 bolts, \\i inches in diameter, set 12

inches in the masonry.Spans 101 to 150 feet, 2 bolts, 1)4 inches in diameter, set 15

inches in the masonry.Spans greater than 150 feet, 4 bolts, 1 }4 inches in diameter, set

15 inches in the masonry.

Anchor bolts subject to tension shall be designed to engage a mass ofmasonry which will provide a resistance equal to 1% times the calculateduplift.

178 HIGHWAY BRIDGES

3. 6. 54.—Name Plates.

Unless otherwise specified, there shall be a name plate, showing inraised letters and figures the name of the manufacturer and the year ofconstruction, bolted to the bridge near each end, at a point convenient forinspection.

Welding3. 6. 55.—Welding—General.

All welding shall conform to the current Specifications for WeldedHighway and Railway Bridges, Design, Construction, and Repair, of theAmerican Welding Society.

This specification provides for welding (and gas cutting) of base metalconsisting of structural carbon steel (article 4. 6. 2.), or similar low carbonsteel or wrought iron approved by the engineer. Wrought iron shall con

form to the requirements of division IV, section 7.Welding of the following items is permissible under these specifications

but shall be done only if called for on the plans or in the special provisions :

1. Floor expansion devices.2. Railings.3. Built-up shoes, pedestals or expansion rockers.4. Diaphragm connection to beams or other members.5. Stiffeners except that welding transversely across the tension flanges

of beams or girders, which have a flange stress of more than75 per cent of their capacity, will not be permitted.

6. Filler plates.7. Stay plate and lacing connections to members.8. Connections and details of bracing.9. Caps and base plates for trestle columns except where caps sup

porting stringers are welded to the sides of the pile.10. Splicing of steel piling.11. Sidewalk brackets except main tension connection.12. Fastening of cover plates to rolled beams.13. Other incidental parts of the structure.Where a definite amount of riveting is specified as a minimum for

connections, the welded connection shall develop an equivalent strength.

Floor System

3. 6. 56.—r.Stiffness of Floor Members.Floor members shall be designed with special reference to stiffness by

making them as deep as economy or the limiting under clearances willpermit.

3. 6. 57.—Stringers.Stringers, preferably shall be riveted between the floor beams or be

continuous over two or more panels.

3. 6. 58.— Cross Frames.In bridges with wooden floors and steel stringers, intermediate cross

frames (or diaphragms) shall be placed between stringers more than 20feet long.

3. 6. 59.—Floorbeams.Floorbeams, preferably shall be at right angles to the trusses or main

girders and shall be rigidly connected thereto. Usually floorbeam connections shall be located above the bottom chord and, in riveted work, thebottom lateral system shall engage both the bottom chord and the floor-beam. In pin-connected trusses, if the floorbeams are located below the

DESIGN 179

bottom chord pins, the vertical posts shall be extended below the pins tomake a rigid connection to the floorbeam.

3. 6. 60.—End Floorbeams.

There shall be end floorbeams in all square-ended truss and girderspans and, preferably in skew spans. End floorbeams for truss spans,preferably shall be designed to permit the use of jacks for lifting thesuperstructure. For this case the allowable stresses may be increased50 per cent.

End floorbeams shall be arranged to permit painting of the side of thebeam adjacent to the abutment backwall.

3. 6. 61.—End Panels of Skew Bridges.

In skew bridges without end floorbeams, the end panel stringers shallbe secured in correct position by end struts connected to the stringers andto the main trusses or girders. The end panel lateral bracing shall beattached to the main trusses or girders and also to the end struts. Adequate provision shall be made for the expansion movement of stringers.

3. 6. 62.—End Connection of Floorbeams and Stringers.

The end connection shall be designed for the loads specified. The end

connection angles of floorbeams and stringers shall be not less than % inchin finished thickness. Except in cases of special end floorbeam details,each end connection for floorbeams and stringers shall be made with twoangles. The length of these angles shall be as great as the flanges willpermit. Bracket or shelf angles which may be used to furnish supportduring erection shall not be considered in determining the number of rivetsrequired to transmit end shear.

End connection details shall be designed with special care to provideclearance for the driving of field connection rivets.

Where timber stringers frame into floorbeams, shelf angles with stiffen-ers shall be provided to carry the whole reaction. Shelf angles shall be

not less than %6 inch thick.Any type of floorbeam hanger which will permit the rotation or the

longitudinal motion of the floorbeam shall not be used.

3. 6. 63.—Sidewalk Brackets.

Sidewalk brackets shall be connected in such a way that the bendingstresses will be transferred directly to the floorbeams.

3. 6. 64.—Expansion Joints.To provide for expansion and contraction movement, floor expansion

joints shall be provided at the expansion ends of all spans and at otherpoints where they may be necessary.

Apron plates, when used, shall be designed to bridge the joint and to

prevent, so far as practicable, the accumulation of roadway debris uponthe bridge seats. Preferably, they shall be connected rigidly to the end

floorbeam.

Bracing3. 6. 65.—General.

Bracing shall be composed of angles or other shapes.If a double system of bracing is used, both systems may be considered

effective simultaneously if the members meet the requirements both as

tension and compression members. The members shall be connected at theirintersections.

180 HIGHWAY BRIDGES

3. 6. 66.—Minimum Size of Angles.The smallest angle used in bracing shall be 3 by 2% inches. There

shall be not less than three rivets in each end connection of the angles.

3. 6. 67.—Lateral Bracing.Through truss spans, deck truss spans and spandrel braced arches

shall have top and bottom lateral bracing.Lateral bracing is not required for deck plate girder or beam spans

of less than 125 feet which have a steel or concrete floor keyed or attachedto the supporting members and which are supported laterally by substantialcross frames or diaphragms.

Deck plate girder or beam spans more than 40 feet in length whichhave a timber floor shall have at least one system of lateral bracing incombination with substantial cross frames or diaphragms.

The spacing of cross frames or diaphragms shall not exceed 25 feet.Adequate temporary bracing shall be placed, if necessary during construction.

The lateral bracing of compression chords, preferably shall be as deep

as the chords and effectively connected to both flanges.

3. 6. 68.—Portal and Sway Bracing.Through truss spans shall have portal bracing, preferably, of the

2-plane or box type, rigidly connected to the end post and the top chordflanges, and as deep as the clearance will allow. If a single-plane portalis used, it shall be located, preferably, in the central transverse plane ofthe end posts, with diaphragms between the webs of the posts to providefor a distribution of the portal stresses. The portal bracing shall be

designed to take the full end reaction of the top chord lateral system andthe end posts shall be designed to transfer this reaction to the truss bearings.

Deck truss spans shall have sway bracing in the plane of the endposts and at all intermediate panel points. This bracing shall extend thefull depth of the trusses below the floor system. The end sway bracingshall be proportioned to carry the entire upper lateral stress to the supportsthrough the end posts of the truss.

Through truss spans shall have sway bracing 5 feet or more deep ateach intermediate panel point. Top lateral struts shall be at least as deep

as the top chord.

3. 6. 69.—Deck Plate Girder Spans.

Deck plate girder spans shall be provided with cross frames at eachend, proportioned to resist the lateral forces, and shall have intermediatecross frames at intervals not exceeding 25 feet. Cross frames shall be

connected to the outstanding legs of the stiffener angles and to the girderflanges.

3. 6. 70.—Half-through Truss Spans.

The vertical truss members and the floorbeams and their connectionsin half-through truss spans shall be proportioned to resist a lateral force ofnot less than 300 pounds per linear foot, applied at the top chord panelpoints of each truss.

The top chord shall be considered as a column with elastic lateral supports at the panel points. The critical buckling force of the column, so determined, shall exceed the maximum force from dead load, live load and impact in any panel of the top chord by not less than 50 per cent.*

* For a discussion of columns with elastic lateral supports, refer to Timoshenko, "Theoryof Elastic Stability," Mc-Graw-Hill Book Co., first edition, page 122.

DESIGN 181

3. 6. 71.—Through Plate Girder Spans.Through plate girder spans shall be stiffened against lateral deforma

tion by means of gusset plates, or knee braces with solid webs, attached tothe stiffener angles and floorbeams. These braces generally shall extend tothe clearance line. If the unsupported length of the inclined edge of thegusset plate exceeds 60 times its thickness, the gusset plate shall have 1 or2 stiffening angles riveted along its edge.

3. 6. 72.—Bracing of Long Columns.

The bracing of long columns shall be designed to fix the column inboth the lateral and the longitudinal directions, at or near the same point.

Plate Girders3. 6. 73.—General.

Plate girders shall be proportioned by the moment of inertia method.In calculating the net moment of inertia, the gravity axis of the grosssection shall be used and the moment of inertia of all holes each side of theaxis shall be deducted. The tensile stress shall be computed from the momentof inertia of the entire net section and the compressive stress from the moment of inertia of the entire gross section.

The compression flanges of plate girders supporting timber floors shallnot be considered to be laterally supported by the flooring unless the floorand fastenings are specially designed to provide adequate support.

3. 6. 74.—Flange Sections.

The flange angle shall form as large a part of the area of the flangeas practicable. Side plates shall not be used except where flange anglesexceeding % inch in thickness otherwise would be required. The area ofcover plates shall not exceed 50 per cent of the total flange area (includingone-eighth of web) except when the heaviest flange angles are used, inwhich case it shall not exceed 60 per cent.

The gross area of the compression flange shall be not less than thegross area of the tension flange.

Flange plates shall be of equal thickness, or shall decrease in thickness from the flange angles outward. No plate shall have a thicknessgreater than that of the flange angles.

If flange plates are used, at least one plate of the top flange shallextend the full length of the girder, except where the flange is to be coveredwith concrete. Any additional flange plates shall extend at least 1 footbeyond the theoretical end but shall be not less than 2d+3 feet in length,and there shall be a sufficient number of rivets at each end of each plateto develop its full stress value before the end of the next outside plate is

reached. The term "d" equals the depth of girder.

3. 6. 75.—Thickness of Web Plates.

The thickness of web plates, except those to be encased in concrete or

those properly stiffened longitudinally, shall be not less than Vi70 D forcarbon steel, not less than ^45 D for silicon steel, not less than ^40 D forlow-alloy steel and not less than Vi30 D for nickel steel, in which "D" is

the clear distance in inches between flanges (including side plates).When one longitudinal stiffener is used, properly located with respect

to the toe of the compression flange and of adequate rigidity, both as provided in article 3. 6. 81, the thickness of web plates shall be not less than

%70 D for carbon steel, not less than ^30 D for silicon steel, not less than

182 HIGHWAY BRIDGES

Mao D for low-alloy steel and not less than %io D for nickel steel, in which"D" is the clear distance in inches between flanges (including side plates).

3. 6. 76.—Flange Rivets.

The number of rivets connecting the flange angles to the web plateshall be sufficient to develop the increment of flange stress transmitted tothe flange angles, combined with any load that is applied directly to theflange.

Legs of angles 5 inches or greater in width, connected to either webplates or cover plates, shall have two lines of rivets. Cover plates over14 inches wide shall have four lines of rivets.

3.6.77.—Flange Splices.

Splices in flange parts shall not be used except by special permissionof the engineer. In general, not more than one part shall be spliced at thesame cross section. If practicable, splices shall be located at points wherethere is an excess of section. The strength of the splice shall be asspecified in article 3. 6. 31. Flange angle splices shall consist of two angles,one at each side of the girder.

3. 6. 78.—Web Splices.

Web plates shall be splicea symmetrically by plates on each side. Thestrength of the splice for shear and moment shall be as specified in article3. 6. 31. The splice plates for shear shall extend the full depth of thegirder between flanges. In the splice there shall be not less than two rowsof rivets on each side of the joint.

3. 6. 79.—Transverse End Stiffeners.

Over the end bearings of plate girders there shall be stiffener angles,the outstanding legs of which shall extend as nearly as practicable to theouter edge of the flange angles. End stiffeners shall be proportioned forbearing on the outstanding legs of the flange angles, no allowance beingmade for the portions of the legs fitted to the fillets of the flange angles.End stiffeners shall be arranged, and there shall be a sufficient number ofrivets in their connection to the web, to transmit the entire end reactionto the bearings. They shall not be crimped.

3. 6. 80.—Transverse Intermediate Stiffeners.

The webs of plate girders shall be stiffened at intervals not greaterthan:

(1) 6 feet, or the clear unsupported depth of the web(2) The distance given by the formula

9000 td — in which

vrd = the clear distance between stiffeners in inches,

t = the thickness of web plates in inches.s = the average unit shearing stress, gross section in the web at

the point considered.

Intermediate transverse stiffeners may be omitted if the depth of theweb between the flange angles, or between the side plates, if there are sideplates, is less than 60 times the thickness of web for carbon steel, 55 timesfor silicon steel, 52 times for low-alloy steel, or 50 times for nickel steel.

Intermediate stiffener angles shall be placed at points of concentrated

DESIGN 183

loading and shall be so designed as to transmit the reactions to the girderweb. Such stiffeners shall not be crimped.

Intermediate stiffener angles generally shall be riveted in pairs to theweb of the girder. The width of the outstanding leg shall not be more than16 times its thickness, and not less than 2 inches plus %o of the depth ofthe girder.

3. 6. 81.—Longitudinal Stiffeners.

The gage line of the longitudinal stiffener shall be % D from the toeof the compression flange. The longitudinal stiffener shall be proportionedso that:

IE = Minimum moment of inertia of longitudinal stiffener aboutthe edge in contact with web plate.

D = Clear distance between flanges,t = Thickness of web plate.d = Clear distance between transverse stiffeners.

Longitudinal stiffeners do not need to be continuous and may be cut attheir intersection with transverse stiffeners.

3. 6. 82.—Ends of Through Girders.

The upper corners of through plate girders, where exposed, shall berounded to a radius consistent with the size of the flange angles and thevertical height of the girder above the roadway. The first flange plate, ora plate of the same width, shall be bent around the curve and continued tothe bottom of the girder. In a bridge consisting of 2 or more spans, onlythe corners at the extreme ends of the bridge need be so rounded unless thespans have girders of different heights. In such a case the higher girdersshall have their top flanges curved down at the ends to meet the top cornersof the girders in the adjacent spans.

3. 6. 83.—Sole Plates.

Sole plates of plate girders shall have a thickness of not less than %inch and not less than the thickness of the flange angles plus % inch.Preferably, they shall not be longer than 18 inches.

3. 6. 84.—Masonry Bearings.

Ends of girders on masonry shall be so supported on metal pedestalsthat the bottom flanges will be above the bridge seat, preferably not lessthan 6 inches.

3. 6. 85.—Camber.

In general, camber will not be required in plate girders except for longspans or special conditions. When required, it shall be in the amountspecified by the engineer.

3. 6. 86.—General.

Preference will be given to trusses with single intersection web systems. Members shall be symmetrical about the central plane of the truss.

Trusses, preferably shall have inclined end posts. Laterally unsupported hip joints shall be avoided.

Where

Trusses

184 HIGHWAY BRIDGES

3. 6. 87. —Top Chords and End Posts.

Top chords and end posts usually shall be made of two side segmentswith one cover plate, and with stay plates and lacing on the open side.

If the shape of the truss permits, compression chords shall be continuous. The splice shall be as near the panel point as practicable and, preferably on the side of the panel point where the smaller stress occurs.

3. 6. 88 Bottom Chords.

The bottom chords of riveted trusses generally shall be spliced nearpanel points and on the side of the panel points where the smaller stressoccurs.

In bottom chords composed of angles the vertical legs of the anglesshall preferably extend downward.

3. 6. 89.—Working Lines and Gravity Axes.

In compression members of unsymmetrical section, such as chord sec

tions formed of side segments and a cover plate, the gravity axis of thesection shall coincide as nearly as practicable with the working line, exceptthat eccentricity may be introduced to counteract dead load bending. In2-angle bottom chord or diagonal members, the working line may be takenas the gage line nearest the back of the angle.

3. 6. 90.—Camber.

The length of the truss members shall be such that the camber will be

equal to or greater than the deflection produced by the dead load.

3. 6. 91.—Riveted Tension Members in Pin-Connected Trusses.

In pin-connected trusses the hip verticals and members performingsimilar functions, and the bottom chords in the first two panels at each end,shall be riveted members.

3. 6. 92.— Counters.

If web members are subject to reversal of stress, their end connectionshall be riveted. Counters, preferably shall be rigid. Adjustable counters,if used, shall have open turnbuckles, and in the design of these members anallowance of 10,000 pounds shall be made for initial stress. Only one setof diagonals in any panel shall be adjustable. Sleeve nuts and loop barsshall not be used.

3. 6. 93 Eyebars.

The thickness of eyebars shall be not less than % of the width, norless than % inch, and not greater than 2 inches. The section of the headthrough the center of the pin hole shall exceed that of the body of thebar by at least 35 per cent. The form of the head shall be submitted to theengineer for approval before the bars are made. The diameter of the pinshall be not less than 0.8 of the width of the widest bar through which itpasses.

3. 6. 94.—Packing of Eyebars.

The eyebars of a set shall be symmetrical about the central plane ofthe truss and as nearly parallel as practicable. The inclination of any barto the plane of the truss shall not exceed Me inch to a foot. Bars shall be

as close together as practicable and held against lateral movement, but theyshall be so arranged that adjacent bars in the same panel will be separatedby at least % inch.

DESIGN 185

Intersecting diagonal bars not far enough apart to clear each otherat all times shall be clamped together at the intersection.

Steel filling rings shall be provided, if needed, to prevent lateral movement of eyebars or other members connected on the pin.

3. 6. 95.—Diaphragms.

There shall be diaphragms in the trusses at the end connections offloorbeams.

The gusset plates engaging the pedestal pin at the end of the trussshall be connected by a diaphragm. Similarly, the webs of the pedestalshall, if practicable, be connected by a diaphragm.

There shall be a diaphragm between gusset plates engaging mainmembers if the end tie plate is 4 feet or more from the point of intersectionof the members.

3. 6. 96.—Sole Plates.

Sole plates of trusses shall be not less than % inch thick.

3. 6. 97.—Masonry Bearings.

Trusses on masonry shall be so supported on metal plates or pedestalsthat the bottom chords will be above the bridge seat, preferably not lessthan 6 inches.

Viaducts3. 6. 98.—Type.

Viaducts shall consist of rolled beam sections, plate girders or rivetedtrusses supported on bents, and usually arranged in alternate tower spansand free spans.

3. 6. 99.—Bents and Towers.

Bents, preferably shall be composed of two supporting columns, andthe bents usually shall be united in pairs to form towers.

3. 6. 100 Batter.

Bents, preferably shall have a sufficient spread at the base to preventuplift under the assumed lateral loadings. In general, the width of a bentat its base shall be not less than one-third of its height.

3. 6. 101.—Single Bents.

Single bents shall have hinged ends or else shall be designed to resistbending.

3. 6. 102. —Bracing.

Towers shall be braced, both transversely and longitudinally, with stiffmembers having riveted connections. The sections of members of longitudinal bracing in each panel shall not be less than those of the membersin corresponding panels of the transverse bracing.

Column splices shall be above and close to the panel points of thebracing.

Horizontal diagonal bracing shall be placed in all towers having morethan two vertical panels, at alternate intermediate panel points.

3. 6. 103.—Bottom Struts.

The bottom struts of viaduct towers shall be strong enough to slide themovable shoes with the structure unloaded, the coefficient of friction beingassumed as 0.25. Provision for expansion of the tower bracing shall be

made in the column bearings.

186 HIGHWAY BRIDGES

3. 6. 104. —Depth of Girders.

The depth of girders in viaducts, preferably shall be uniform.

3. 6. 105. —Girder Connections and Bracing.Girders of tower spans shall be fastened at each end of the tops of

the columns or to the cross girders. Preferably, there shall be a line ofgirders resting directly over the columns. One end of the girders betweentowers shall be riveted to the support, and there shall be an effective expansion bearing at the other end. No bracing or sway frame shall be commonto abutting spans.

If girders are not supported directly on the column, provision shall bemade for the transmission of the longitudinal forces to the tower bracing.

3. 6. 106. —Sole and Masonry Plates.

Sole plates, masonry plates, and cap plates shall be not less than %inch thick.

SECTION 7—Concrete Design

3. 7. 1.—General Assumptions.

The design of reinforced concrete members under these specificationsshall be based on the following assumptions:

(1) Calculations are made with reference to unit working stresses andsafe loads, as elsewhere specified herein, rather than with reference toultimate strength and ultimate loads.

(2) A plane section before bending remains plane after bending.

(3) The modulus of elasticity of concrete in compression is constantwithin the limits of working stresses; the distribution of compressive stressin flexure is, therefore, rectilinear.

(4) The ratio "n" shall be assumed as follows:

Values of n=|rEc

Ultimate strength of concrete, For computations For computationsLbs. per sq. in. of strength of deflection

2,000 to 2,400 15 \2,500 to 2,900 12 j3,000 to 3,900 10 > 8

4,000 to 4,900 8 i5,000 or more 6 >

In computing the ultimate deflection of slabs and beams, the value ofthe modulus of elasticity of concrete should be assumed as one-twelfth thatof steel in order to allow for the effect of plastic flow.

(5) Concrete shall be assumed as offering no tensile resistance.

(6) The bond between concrete and metal reinforcement is assumed toremain unbroken throughout the range of working stresses. Under compression the two materials are therefore stressed in proportion to theirmoduli of elasticity.

(7) Initial stress in the reinforcement, due to contraction or expansionof the concrete, is neglected, except in the design of reinforced concretecolumns.

(8) For the determination of external reactions, moments, shears, anddeflections, moments of inertia of rigid frame and continuous structuresshall be computed for the gross concrete sections, neglecting the effect ofsteel reinforcing, except that the transformed area of the steel shall be included for columns, arches or other compressive members.

DESIGN 181

(9) The moment of inertia of the entire superstructure sections, exceptrailings or any curbs or sidewalks not placed monolithically with the superstructure before the falsework is released, and the moment of inertia ofthe full cross section of the pier or bent shall be used to determine theelastic properties of the various spans and supports.

(10) The depth of girder or slab to be used in computing moment ofinertia at the centerline of support shall be obtained by extending the slopeof the intrados of the member to the centerline.

(11) Rigid frames shall be considered free to sway longitudinally dueto the application of vertical dead loads and vertically applied live loads,except when the structure is restrained from movement by external forces.

(12) The assumption of no moment restraint at the base of column shallbe used in the analysis of rigid frames (superstructures) unless the base isknown to be fully fixed. When a pinned end condition is assumed for theanalysis of the superstructure, the base of column, footing and piling shallbe designed to resist the moment resulting from an assumed restraint varying from zero to full fixity. The degree of restraint shall be determinedby the type of footing and the character of the foundation material.

(13) Piers or bents constructed integrally with footings placed on a

skew exceeding 10° shall be considered fixed at the top of footing.

3. 7. 2.—Standard Notations.

(a) Rectangular Beams.

fs= tensile unit stress in longitudinal reinforcement.fc = compressive unit stress in extreme fiber of concrete.

Ea= modulus of elasticity of steel.Ec= modulus of elasticity of concrete.

M = bending moment, or moment of resistance in general.As = effective cross sectional area of tension reinforcement,

b = width of beamd = effective depth, or depth from compression surface of beam to center

of tension reinforcement.k=ratio of depth of neutral axis to effective depth, d.j = ratio of lever arm of resisting couple to depth, d.

jd=d— z=arm of resisting couple.p= ratio of effective area of tension reinforcement to effective area of

concrete in beam =bd

z = depth from compression surface of beam to resultant of compressivestresses.

(b) T-Beams.b = width of flange,

b' = width of stem.t= thickness of flange.

(c) Beams Reinforced for Compression.

A' = area of compressive steel.p'= ratio of effective area of compression reinforcement to effective area

A'of concrete in beam ■■=(—r

bd

f '« ••compressive unit stress in longitudinal reinforcement.C — total compressive stress in concrete.

188 HIGHWAY BRIDGES

C'= total compressive stress in steel.d' = depth from compression surface of beam to center of compression

reinforcement.z = depth from compression surface of beam to resultant of compressive

stresses.

(d) Shear, Bond and Web Reinforcement.V= total shear.V' = external shear on any section after deducting that carried by the

concrete,

v = shearing unit stress.u = bond stress per unit of area of surface of bar.o = perimeter of bar.

So = sum of perimeters of bars in one set.a = spacing of web reinforcement bars, measured perpendicular to their

direction.s= spacing of web reinforcement bars, measured at the neutral axis and

in the direction of the longitudinal axis of the beam.Av = total area of web reinforcement in tension within a distance, a, of the

total area of all bars bent up in any one plane,o = angle between web bars and longitudinal bars.

fv= tensile unit stress in web reinforcement.

3. 7. 3.—Design Formulas.

(a) Flexure of Rectangular Reinforced Concrete Beams and Slabs.Computations of flexure in rectangular reinforced concrete beams and

slabs shall be based on the following formulas:(1) Reinforced for tension only : (See figure 7)

Position of neutral axis,

k = V2pn + (pn)2 - pn.

Arm of resisting couple,

3-1-3Compressive unit stress in extreme fiber of concrete

. 2M 2pf8IC =7

jkbd2 k

Tensile unit stress in longitudinal reinforcement

fM . - M

8Asjd^pjbd2'

Steel ratio for balanced reinforcement

1V=V2

fcUfc )Note —For approximate computations, the following assumptions may be

made:

A"VsUd

, 6Mfc=bd2

(2) Reinforced for both tension and compression: (See figure 8)

DESIGN 189

Jt>,


k =|/2n(p+p'jj-')+n2(p+p')2-n(p+p').

Position of resultant compression,

Kk3d+2p'nd'(k-^).

k*+2p'n(k-j)Arm of resisting couple,

jd = d— z.Compressive unit stress in extreme fiber of concrete.

6M

''"C*-^k-f) K)]Tensile stress in longitudinal reinforcement,

Mfs

'pjbd^-

Compressive stress in longitudinal reinforcement,

f'.-nf.^k~H-^.

(b) Flexure of Reinforced Concrete T-Beams: (See figure 9)Computations of flexure in reinforced concrete T-beams shall be based on th

following formulas:

(a) Neutral axis in the flange:Use the formulas for rectangular beams and slabs.

(b) Neutral axis below the flange:The following formulas neglect the compression in the stem :

Position of neutral axis,'

, 2ndAi+bt»2nAs+2bt

'

Position of resultant compression, , ;

=/3kd-2t\t <

.;

z-^2kd-t h' V

Arm of resisting couple,jd = d— z.

Compressive unit stress in extreme fiber of concrete,

=Mkd U k \,

0 bt(kd-}^t)jd nU-kjTensile unit stress in longitudinal reinforcement,

f,

M

8

Asjd

[For approximate results, the formulas for rectangular beams may be used).

190 HIGHWAY BRIDGES

The following formulas take into account the compression in the stem :

they are recommended where the flange is small compared with the stem:


/2ndA.+(b-b')t* , ^ nA. + (b-b')t'V nA.+(b-b')txa-y p +\ b' ) b'

Position of resultant compression,

(kdt2 - %t»)b+[(kd-t)»(t+M(kd-t))]b>Z=t(2kd-t)b+(kd-t)2b'

Arm of resisting couple,jd = d— z.

Compressive unit stress in extreme fiber of concrete

2Mkd*

[(2kd -t)bt+(kd -t)*b'] jd

Tensile unit stress in longitudinal reinforcement,

fs Aljd

(c) Shear, Bond and Web Reinforcement:Diagonal tension and shear in reinforced concrete beams shall be calcu

lated by the following formulas:

Shearing unit stress,

Vbjd

Stress in vertical web reinforcement.

f - V'sT Avjd

When a series of web bars or bent-up longitudinal bars is used, theweb reinforcement shall be designed in accordance with the formula:

^ _ V'a V's sin a

T_fvjd= fvjd

When the web reinforcement consists of bars bent up in a single planeso as to reinforce all sections of the beam which require it, the bent-up barsshall be designed in accordance with the formula:

fv sin a

The bond between concrete and reinforcement bars in reinforced concrete beams and slabs shall be computed by the formula:

VjdZo

(For approximate results "j," in the above formulas, may be taken as %.)

As regards shear and bond stress for tensile steel, the above formulasapply also to beams reinforced for compression.

DESIGN 191

FIGURE 9

192 HIGHWAY BRIDGES

(d) Columns with Lateral Ties.

The safe load for short and long columns shall he determined accordingto formulas given in article 3. 4. 11.

(e) Spiral Columns.

The safe load for spiral columns shall he determined according toformulas given in article 3. 4. 11.

3. 7. 4.—Span Lengths.

The effective span lengths of slabs shall be as specified in article 3. 3. 2.

The effective span length of freely supported beams shall not exceed

the clear span plus the depth of beam.

For the analysis of all rigid frames, the span lengths shall be takenas the distance between the centers of bearings at the top of the footings.

The span length of continuous or restrained floor slabs and beams shallbe the clear distance between faces of support. Where fillets making anangle of 45 degrees or more with the axis of a continuous or restrained slabare built monolithic with the slab and support, the span shall be measuredfrom the section where the combined depth of the slab and fillet is at leastone and one-half times the thickness of slab. Maximum negative momentsare to be considered as existing at the ends of the span, as above defined.No portion of the fillet shall be considered as adding to the effective depthof the slab.

3. 7. 5.—Expansion.

In general, provision for temperature changes shall be made in allsimple spans having a clear length in excess of 40 feet.

In continuous bridges, provision shall be made in the design to resistthermal stresses induced or means shall be provided for movement causedby temperature changes.

Expansion not otherwise provided for shall be provided by means ofhinged columns, rockers, sliding plates or other devices.

3. 7. 6.—T-Beams.

(a) Effective Flange Width.

In beam and slab construction, effective and adequate bond and shearresistance shall be provided at the junction of the beam and slab. The slabmay then be considered an integral part of the beam, but its assumedeffective width as a T-beam flange shall not exceed the following:

(1) One-fourth of the span length of the beam.

(2) The distance center to center of beams.

(3) Twelve times the least thickness of the slab plus the width of thegirder stem.

For beams having a flange on one side only, the effective overhangingflange width shall not exceed one-twelfth of the span length of the beam,nor six times the thickness of the slab, nor one-half the clear distance tothe next beam.

(b) Shear.

The flange shall not be considered as effective in computing the shearand diagonal tension resistance of T-beams.

DESIGN 193

(c) Isolated Beams.

Isolated beams, in which the T-form is used only for the purpose ofproviding additional compression area, shall have a flange thickness of notless than one-half the width of the web, and a total flange width of notmore than 4 times the width of web.

(d) Diaphragms.

For T-beam spans over 40 feet in length diaphragms or spreaders shallbe placed between the beams at the middle or at the third points.

3. 7. 7.—Reinforcement.

(a) Spacing.

The minimum spacing center to center of parallel bars shall be 2% timesthe diameter of round or 3 times the side dimensions of square bars, but inno case shall the clear distance between the bars be less than 1% times themaximum size of the coarse aggregate.

(b) Covering.

The minimum covering, measured from the surface of the concrete tothe face of any reinforcing bar, shall be not less than 2 inches except inslabs where the minimum covering shall be 1 inch. In the footings ofabutments and retaining walls and in piers the minimum covering shal'be 3 inches. In work exposed to the action of sea water the minimumcovering shall be 4 inches except in precast concrete piles, where a minimumof 3 inches may be used.

(c) Splicing.

Tensile reinforcement shall not be spliced at points of maximum stress.When reinforcement is spliced, the spliced bars shall lap sufficiently todevelop the full strength in bond.

(d) Allowable Capacity of End Anchorage —Hooks.

End anchorage shall be designed to develop a stress of 10,000 poundsper square inch in the bars. End anchorage may be an extension of thebar or a hook. In either case the additional length of bar should provide theneeded anchorage by normal bond stress, assumed to be uniformly distributed over the additional embedded surface. A properly dimensionedhook is one in which the bar is bent in a full semicircle, with a radius ofbend not less than 3 diameters, plus an extension at the free end of atleast 4 bar diameters. Right angles or other abrupt bends, which do notengage a structural steel member, are not to be considered as anchorageunless the radius of the bend is at least 4 bar diameters and the total lengthfrom beginning of bend to the free end of the bar is at least 16 bardiameters.

(e) Extension of Reinforcement.

(1) To provide for contingencies arising from unanticipated distribution of loads, yielding of supports, shifting of points of inflection, orother lack of agreement with assumed conditions governing the design ofelastic structures, the reinforcement shall be extended at the supports andat other points between the supports as indicated in (2) to (5) below.These paragraphs relate to ordinary anchorage and are the minimum re

194 HIGHWAY BRIDGES

quirements under which normal working stresses for bond or shear arepermitted.

(2) Negative tensile reinforcement at the supported end of a restrainedor cantilever beam or member of a rigid frame shall be extended in orthrough the supporting member in such a manner as to develop the maximumtension in the bar with a bond stress not exceeding the normal .workingstress provided in article 3. 4. 12.

(3) Between the supports of continuous or simple beams, every reinforcing bar shall be extended at least 15 diameters but not less than %oof the span length, beyond the point at which computations indicate it isno longer needed to resist stress.

(4) In simple beams and freely supported ends of continuous beams, atleast Va of the positive reinforcement shall extend beyond the face of thesupports a distance sufficient to develop V2 the allowable stress in the bars.

(5) In restrained or continuous beams at least % of the positive reinforcement shall extend beyond the face of the supports and the remaindertreated as provided in (3).

(f) Maximum Sizes.

The maximum size of bar reinforcement shall be 1% inches square orequivalent, unless the particular conditions warrant the adoption of specialreinforcement design. When structural steel shapes are used for reinforcement, no section having a surface area per foot of length of more than 150

square inches shall be used as a reinforcing member unless mechanical bondis provided by means of lugs, bars or other details which will effectivelybond the member to the surrounding concrete mass.

3. 7. 8. —Compression Reinforcement in Beams.

Compression reinforcement in girders and beams shall be securedagainst buckling by ties or stirrups adequately anchored in the concrete,and spaced not more than 16 bar diameters apart. Where compression reinforcement is used, its effectiveness in resisting bending may be taken as

twice the value indicated from the calculations assuming a straight-linerelation between stress and strain and the modular relation of stress in steelto stress in concrete given in article 3. 7. 1. (4). However, in no case shoulda stress in compression reinforcement greater than 16,000 pounds persquare inch be allowed.

3. 7. 9.—Web Reinforcement,

(a) General.

When the allowable unit shearing stress for concrete is exceeded, webreinforcement shall be provided by one of the following methods:

(1) Longitudinal bars bent up in series or in a single plane.

(2) Vertical stirrups.(3) Combination of bent-up bars and vertical stirrups.

When any of the above methods of reinforcement are used, the concretemay be assumed to carry external vertical shear not to exceed 60 pounds persquare inch for bars not anchored nor 90 pounds per square inch for barsanchored, the remainder of the shear being carried by the webreinforcement.

The webs of T-beams shall be reinforced with vertical stirrups in allcases.

DESIGN 195

(b) Bent-up Bars.

Bent-up bars used as web reinforcement may be bent at any anglebetween 20 and 45 degrees with the longitudinal reinforcement. The radiusof bend shall not be less than 4 diameters of the bar.

The spacing of bent-up bars shall be measured at the neutral axis andin the direction of the longitudinal axis of the beam. This spacing shallmeet the requirements of article 3. 7. 3 (c) and shall not exceed three-fourths the effective depth of the beam. The first bar from the supportshall cross the mid-depth of the beam at a distance from the face of thesupport, measured parallel to the longitudinal axis of the beam, not greaterthan one-half the effective depth.

(c) Vertical Stirrups.

The spacing of vertical stirrups shall not exceed three-fourths of theeffective depth of the beam. The first stirrup shall be placed at a distancefrom the face of the support not greater than one-fourth of the effectivedepth of the beam. Stirrups shall surround three sides of the tensilereinforcement.

(d) Anchorage.

(1) The stress in a stirrup or other web reinforcement shall not exceed

the capacity of its anchorage in the upper or lower one-half of the effectivedepth of the beam.

(2) Web reinforcement which is provided by bending into an inclinedposition one or more bars of the main tensile reinforcement where notrequired for resistance to positive or negative bending, may be consideredcompletely anchored by continuity with the main tensile reinforcement, orby embedment of the requisite length in the upper or lower half of the beam,provided at least one-half of such embedment is as close to the upper orlower surface of the beam as the requirements of fire and rust protectionallow. A hook placed close to the upper or lower surface of the beam maybe substituted for a portion of such embedment.

(3) Stirrups shall be anchored at both ends by one of the followingmethods, or by a combination thereof:

(a) Rigid attachment, as by welding, to the main longitudinal reinforcement.

(b) Bending around and closely in contact with a bar of the longitudinal reinforcement, in the form of a U-stirrup or hook.

(c) A hook placed as close to the upper or lower surface of the beamas the requirements of fire and rust protection will allow. In estimating the capacity of this anchorage the stress developed by bondbetween midheight of the beam and the center of bending of thehook may be added to the capacity of the hook.

(d) An adequate length of embedment in the upper or lower one-halfof the effective depth of the beam, whether straight or bent.Anchorage of this type alone should not be relied on for stirrups incases where the shearing stress in the web exceeds that recommended for beams without end anchorage of the reinforcement.

(See article 3.4. 12.)

3. 7. 10.—Columns,

fa) General.

The ratio of unsupported length of plain concrete piers and pedestals

196 HIGHWAY BRIDGES

to their least dimension shall not exceed 3. The minimum dimension of anycolumn shall be 15 inches.

For the design of short and long columns see article 3. 4. 11.

(b) Columns icith Lateral Ties.

The reinforcement of columns shall consist of at least 4 longitudinalbars tied together with laterial ties or hoops enclosing the longitudinal reinforcement.

The longitudinal reinforcement shall be of bars not less than %-inch indiameter and shall have a total cross sectional area of not less than 1.0

per cent of the total cross sectional area of the column except that thispercentage may be reduced in the case of columns or pier shafts which, forarchitectural reasons, have a larger cross section than required by con

siderations of loading.

Reinforcement in excess of 4 per cent of the cross sectional area of thecolumn shall not be considered in computing compressive stresses. Thelateral ties or hoops shall be not less than inch in diameter and spacednot farther apart than 12 inches.

(c) Spiral Columns.

(1) The longitudinal reinforcement shall consist of at least six bars ofminimum diameter of % inch and of an effective cross sectional area notless than 1 per cent nor more than 6 per cent of that of the core. Thenumber of bars concentrated in the ring at the periphery of the core shall begoverned by the spacing requirements for parallel bars in beams and incase all the bars cannot be placed at the periphery of the core, the barswithin shall be stayed at intervals of 24 inches and shall not be nearer tothe outer ring than %o times the core diameter.

(2) The ratio of the spiral reinforcement shall be not less than one-fourth the ratio of the longitudinal reinforcement. Spiral reinforcementshall consist of evenly spaced continuous spirals held firmly in place andtrue to line by at least three vertical spacer bars. At the ends of all spiralsand at points of splice the outside diameter shall be maintained.

The center to center spacing of the spirals shall not be greater thanone-sixth of the diameter of the core and the clear distance between spiralsshall not exceed 3 inches nor be less than 1 % inches or 1 Vi times the maximum size of the coarse aggregate.

(3) Reinforcement shall be protected everywhere by a covering of concrete cast monolithic with the core having a minimum thickness of 1% inches.

(d) Flexure and Direct Stress.

( 1 ) General.

When columns are subjected to bending stresses due to eccentric loads,monolithic construction or lateral forces, they shall be so proportioned thatthe combined direct and bending stresses shall not exceed the allowable unitcompressive stresses herein specified.

(2) Special Cases.

When the plane of bending does not lie on a principal axis of the columnsection or within the core radius, the position and direction of the neutralaxis shall be determined by a solution of the following formula :

DESIGN 197

P =load parallel to the axis of column, in lbs.A = transformed area of cracked section in sq. in.

Mi = component of moment parallel to X axis.My = component of moment parallel to Y axis.Xo = coordinate distance from center of gravity of the cracked section

parallel to the X axis, in inches.Y0 = coordinate distance from center of gravity parallel to Y axis, in inches.Ii=the amount of inertia of "A" along the X axis about the centroidal

axis Y, in inches4.Iy=the moment of inertia along the axis Y, in inches.4

Ixy= product of inertia of "A" about the axes X and Y through thecentroid.

In solving the above formula it is necessary to assume a value foreither Xo or Yq.

Formulas for Stresses

With the position and the direction of the neutral axis determined, themaximum unit stress in the concrete shall be computed with the formula,

, Myv , Mjv . , . ,f = T^.in or f =^-Xd , in whichly Ix.

Yn = distance from the neutral axis to the extreme fiber in compressionparallel to the Y axis.

Xn = distance to extreme fiber parallel to the X axis.

Note:

The above formulas are based on a study by Professor Hardy Cross on"Column Analogy."* For the procedure and methods employed in the application of the formulas reference is made to an article by William G. S.Saville.t "Analyzing Non-Homogeneous Sections Subjected to Bending andDirect Stress."

(3) Columns in Earth Fills.

Columns placed in earth fills, as in the case of "pedestals" or "buried"abutments, shall be designed to withstand the earth pressure from the rear,disregarding the effect of the fill in front.

3. 7. 11.—Concrete Arches.

(a) Shape of Arch Ring.

Arch rings shall be selected as to shape in such manner that the axisof the ring shall conform, as nearly as practicable, to either the equilibriumpolygon for full dead load or to the equilibrium polygon for full dead plusone-half live load over the full span, whichever produces the smallest bending stresses under combined loads.

* Engineering Experiment Station, University of Illinois, Bulletin No. 215, October14, 1930.

t Civil Engineering, Volume No. 10, March 1940.

198 HIGHWAY BRIDGES

(b) Spandrel Walls.

When the spandrel walls of filled spandrel arches exceed 8 feet in heightabove the extrados they shall be designed as vertical slabs supported bytransverse diaphragm walls or deep counterforts. Vertical cantilever wallsover 8 feet in height, or counterforts having a back slope of less than 45

degrees with the vertical, shall not be used, on account of the excessiveand indeterminate stresses set up in the arch ring by torsion.

(c) Expansion Joints.Vertical expansion joints shall be placed in the spandrel walls of arches

to provide for movement due to temperature change and arch deflection.These joints shall be placed at the ends of spans and at intermediate points,generally not more than 50 feet apart.

(d) Reinforcement.Arch ribs in reinforced concrete construction shall be reinforced with

a complete double line of longitudinal reinforcement consisting of an intra-dosal system and an extradosal system connected by a series of stirrupsor tie-rods.

For barrel arches, a system of transverse reinforcement, thoroughlyanchored to the longitudinal reinforcement, shall be used in both intradosand extrados. The transverse reinforcement shall be proportioned to resistthe bending stresses due to any overturning action of the spandrel wall.

For rib arches, hoops or tie bars shall be used in connection with thelongitudinal rib reinforcement, as in the case of reinforced concrete columns.

(e) Waterproofing.

Preferably, the top of the arch ring and the interior faces of thespandrel walls of all filled spandrel arches shall be waterproofed with a

membrane waterproofing constructed in accordance with the requirementsspecified in division II.

(f) Drainage of Spandrel Fill.The fills of filled spandrel arches shall be effectively drained by a

system of tile drains or French drains laid along the intersection of thespandrel walls and arch rings and discharging through suitable outlets inthe piers and abutments. The location and details of the drainage outletsshall be such as to eliminate, as far as possible, the discoloration by drainagewater of the exposed masonry faces.

3. 7. 12.—Viaduct Bents and Towers.

When concrete columns are used in viaduct construction, bents andtowers shall be effectively braced by means of longitudinal and transversestruts. For height greater than 40 feet, both longitudinal and transversecross or diagonal bracing, preferably, shall be used and the footings for thecolumns forming a single bent shall be thoroughly tied together.

SECTION 8—Timber Structures

3. 8. 1.—Bolts.

Bolts of diameters not exceeding 1 inch, preferably shall be spaced notcloser than 6 inches center to center, not less than 6 inches from the centerof the bolt to the end of any timber, and not less than 2% inches from the

DESIGN 199

center of the bolt to the side of any timber. These distances, preferablyshall be increased for bolts larger than 1 inch in diameter. Inclined boltsthrough timber, preferably, shall be provided with beveled cast washers toeliminate the cutting of inclined daps in the timber.

3. 8. 2 Washers.

A washer shall be used under all bolt heads and nuts which wouldotherwise come in contact with wood. Either cast or plate washers may be

used and they shall be designed to prevent excessive crushing of the woodwhen the bolts are tightened. For bolts in important locations, such as

joints and splices, and for rods, the washers shall be designed to develop thebolt or rod in tension, at the unit-bearing stresses specified for compressionperpendicular to the grain of timber.

A standard circular washer shall be used under the heads of all lagscrews.

3. 8. 3.—Hardware for Seacoast Structures.

The hardware for structures on the seacoast shall be galvanized orcadmium plated.

3. 8. 4.—Columns and Posts.

No column shall have an unsupported length greater than 50 times itsleast dimension.

The strength of built-up columns composed of two or more sticks boltedtogether, either with or without packing blocks, shall be considered as equalto the combined strength of the single sticks each considered as an independent column.

The strength of connector-joined spaced columns shall be determinedas provided in article 3. 4. 14.

3. 8. 5.—Pile and Framed Bents.

(a) Pile Bents.

Pile bents generally shall not exceed 40 feet in height. Pile bents over10 feet high shall be sway-braced transversely with diagonal braces on eachside of the bent, and shall be adequately braced longitudinally. In general,pile bents shall contain not less than four piles each and the outside piles,preferably, shall be battered. The piles shall be designed for safe bearingand for column action.

(b) Framed Bents.

Framed bents may be supported on piles, concrete pedestals or mudsills. All bents shall be sway-braced transversely and adequate provisionshall be made for longitudinal bracing. In general, framed bents shallcontain not less than four posts each and the outside posts of the bent shallbe battered. The posts shall be designed as columns.

(c) Sills and Mud Sills.

Mud sills, and all sills which are to be located in close proximity to theground surface, preferably, shall be given a preservative treatment. Whenpossible, sills shall be located clear of all earth so that there may be a freecirculation of air around them. Sills shall be fastened to mud sills or pileswith drift bolts of not less than %-inch diameter and extending into themud sills or piles at least 6 inches. Sills shall be fastened to pedestals with

9

200 HIGHWAY BRIDGES

dowels of not less than 94 -inch diameter, set in the pedestals and extendinginto the sills at least 6 inches.

Posts shall be fastened to sills by dowels of not less than %-inchdiameter, extending at least 6 inches into the posts and sills, or by driftbolts of not less than %-inch diameter driven diagonally through the baseof the posts and extending at least 9 inches into the sill. Posts shall befastened to pedestals with dowels of not less than %-inch diameter andextending into the posts at least 6 inches.

(d) Caps.

Timber caps shall be not less in size than 10 by 10 inches. They shallbe fastened with drift bolts of not less than %-inch diameter, extending atleast 9 inches into the piles or posts.

(e) Bracing.

Single-story bracing shall not exceed 20 feet in height. The minimumsize of transverse sway braces shall be 3 by 8 inches. All bracing shall be

bolted through the piles, posts or caps at the ends; at intermediate intersections it may be bolted or spiked. In all cases, spikes shall be providedin addition to bolts. The bolts used shall be of not less than %-inch diameter.

(f) Pile Bent Abutments.Pile bent abutments shall be adequately braced or anchored to resist

earth pressure. Bulkhead plank shall be not less than 3 inches thick and,preferably, shall be treated. It shall be fastened to the piles with spikes,the length of which shall be at least 3 inches greater than the thickness ofthe plank.

3. 8. 6.—Trusses.

(a)—Joints and Splices.

Joints shall be detailed to shed water to the maximum degree practicable. Joints and splices shall be designed to develop the computed stressesin the members connected and, preferably, to develop the full strength ofthe members. Posts or struts bearing against the sides of timber members,preferably, shall be provided with metal end bearings. Joints involvingend bearing on inclined surfaces shall be avoided, preference being given tosquare-cut ends of timbers bearing against blocks.

Bearing surfaces of castings connecting timber members shall be milledto provide smooth, even surfaces permitting accurate fitting and completecontact of the wood and metal bearing surfaces. Rolled plates, bars andshapes used in chord splice plates, or other parts bearing upon wood surfaces, shall be true and even. The wood surfaces taking bearing upon metalparts shall be not less than % inch in width. Bolts engaging castings andstructural parts shall hold them rigidly in position so that bending on theparts in contact will be reduced to a minimum. The joint details at trusspanel points shall provide definite lines of action and shall be simple andas susceptible as possible of definite strength analysis. When inclined boltsare used to connect end posts or web members with chord members, theyshall be placed approximately at an angle of not more than 60 degrees withthe latter and when used in conjunction with joint castings, the holes in oneof the connected members shall be bored % inch larger than the nominaldiameter of the bolts. No daps in chords for butt blocks shall be less than% inch deep.

t

DESIGN 201

Splices fox tension members shall be designed to reduce to a minimumthe effects of cross shrinkage of the timber. Neither steel splice plates ofthe batten type nor shear pin splices shall be used when the timbers to be

spliced are more than 8 inches thick, since the shrinkage will permit thejoint to become loose. Shear pin points shall be used only with fully sea

soned timber.

(b) Floor Beams.

Floor beams shall be sized at bearing points. In floor beams composedof two or more timbers, the timbers shall be separated by at least 2 inchesfor air circulation. Floor beams shall be connected to the main truss members by means of rods or structural shapes.

(c) Hangers.

Hangers generally shall be rods having upset ends with a suitablydesigned washer or bearing plate at each end. Upset ends shall conformto the requirements specified for Structural Steel Design, division III.

(d) Eyebars and Counters.

The requirements specified for Structural Steel Design, division III, forcounters, eyebars and eyebar packing shall apply to such members whenused in timber trusses.

(e) Bracing.

Timber trusses shall be provided with a rigid system of laterals in theplane of the loaded chord. When the details will permit, this lateral bracingshall be securely fastened to all longitudinal stringers. Lateral bracing,preferably rigid, in the plane of the unloaded chord, and rigid portal andsway-bracing shall be provided in all trusses having sufficient headroom.Outrigger brackets connected to extensions of the floor beams shall be usedfor bracing through trusses having headroom insufficient for a top lateralsystem.

(f) Camber.

Camber, in addition to that required to provide for dead load andshrinkage, shall be provided in timber trusses in sufficient amount to givethe structure a good appearance.

3. 8. 7.—Floors and Railings.

(a) Stringers.

Stringers shall be of sufficient length to take bearing over the full widthof caps or floor beams, except outside stringers which may have butt joints.Preferably, they shall be of two panel lengths placed with staggered joints.The lapped ends of untreated stringers shall be separated at least % inchfor air circulation. Stringers shall be secured to caps or floor beams.

(b) Bridging.

Stringers shall be braced by cross bridging in each panel. The bridgingshall be not less in size than 2 by 4 inches.

(c) Nailing Strips.When timber floors are supported by steel joists, the joists shall be

provided with nailing strips which shall be bolted either to the top flangesor the webs.

202 HIGHWAY BRIDGES

When nailing strips are bolted to the flanges, they shall be used on alljoists. They shall be not less than 4 inches deep and shall be wider thanthe supporting flange. They shall be secured with %-inch bolts throughthe flanges, spaced not more than 4 feet apart and not more than 18 inchesfrom the ends of the strips.

Nailing strips bolted to the webs shall be not less than 4 inches thickand shall be fastened with bolts spaced not farther apart than 5 feet. Theyshall be held clear of the flanges by blocks between the web and strip, andbolted through the web with %-inch bolts spaced not more than 4 feet apartand not more than 18 inches from the ends of the strips.

(&) Flooring.

Roadway floor plank shall have a nominal thickness of not less than 3

inches. Sidewalk floor plank shall have a nominal thickness of not less than2 inches.

The minimum size of material used for laminated or strip floors shallbe 2 by 4 inches.

(e) Retaining Pieces.

Retaining pieces, where required, shall be not less than 6 inches in width.In general, they shall be secured in place by %-inch bolts at 3-foot intervalsand spiked at 1-foot intervals.

(f) Wheel Guards.

Wheel guards having a cross section of not less than 4 by 6 inches shallbe provided on each side of the roadway. The guard timbers shall be inlengths of not less than 12 feet. They shall be secured with %-inch boltsat the ends and at intermediate points not more than 4 feet apart.

In strip floors or cambered floors, not provided with retaining pieces,the wheel guards shall be placed directly on the flooring with scupper holesat suitable intervals. In other floors the wheel guards shall be supportedby scupper blocks not less than 4 inches thick and 1 foot long, held in placeby spikes and a bolt through the wheel guard and flooring, and spaced notmore than 4 feet center to center.

(g) Drainage.

Adequate provision shall be made for the proper drainage of timberfloors.

(h) Railings.

Wood railings shall consist of not less than 2 horizontal lines of rails.Rails shall have a cross-section not less than 2 by 6 inches.

Rail posts shall have a cross-section not less than 4 by 6 inches andshall be spaced not more than 8 feet apart.

Preferably, rails shall be surfaced 4 sides (S4S) and painted.

3. 8. 8 Fire Stops.

To check the spread of fire lengthwise of the structure, timber floorsor trestles of any considerable length, preferably, shall be provided withfire stops.

In timber floors these fire stops should be provided at intervals of notover 75 feet. They may consist of diaphragms of wood or fire-resistant material at least as thick as the flooring, located over caps or floorbeam andcompletely filling the openings between the joists.

In timber trestle bridges, in addition to the fire stops in the floor, fire

DESIGN 203

curtains should be provided at intervals of 100 feet or more. These curtains may consist of plank or asbestos-covered metal spiked to the bents.They should extend downward from the bottom of the joists at least 5 feetand horizontally at least to the ends of the caps. A fire stop between thejoists should be located over each curtain.

SECTION 9—Composite Beams

3. 9. 1.—General Assumptions:

Specifications pertaining to the design of concrete, steel, and timberstructures shall govern the design of composite beams where such specifications are applicable.

Composite beams shall be proportioned by the moment of inertia methodof the net composite sections.

3. 9. 2.—Effective Flange Width.

In composite beam construction the assumed effective width of the slabas a T-beam flange shall not exceed the following:

(1) One-fourth of the span length of the beam.(2) The distance center to center of beams.

(3) Twelve times the least thickness of the slab.

For beams having a flange on one side only, the effective flange widthshall not exceed one-twelfth of the span length of the beam, nor six timesthe thickness of the slab, nor one-half the distance center to center of thenext beam.

Composite beam type construction shall not be used for isolated beams.

3. 9. 3.—Stresses.

Maximum compressive and tensile stresses in beams, which are notprovided with temporary supports during placing of the permanent deadload, shall be the sum of the stresses produced by the dead loads acting onthe beam before the concrete slab has set and the stresses produced by thesuperimposed loads acting on the composite beam. Where beams are provided with temporary intermediate supports during the placing of thepermanent dead load, the stresses shall be computed on the basis of thecomposite section.

3. 9. 4.—Shear.

Resistance to horizontal shear shall be provided by mechanical meansat the junction of the slab and the beam or girder.

Shear shall be computed by the following formula:

I

in which S = the horizontal shear per linear inch at the junction of theslab and beam at the point of the beam in question.

V = total shear due to superimposed load after concrete in slab hasset.

Q = statical moment (product of the compressive area of slab andthe distance from its center to the neutral axis of the composite section).

I = moment of inertia of composite section.

Spacing of the shear devices shall be determined by dividing the re-

204 HIGHWAY BRIDGES

sistance value of the individual shear device by the shear per linear inch"S," with a maximum spacing of two feet.

The flange of the composite beam shall not be considered effective incomputing the resistance to vertical shear and diagonal tension. Theseforces shall be assumed to be resisted entirely by the beam or girder web.

3. 9. 5.—Deflection.The requirements relative to live load deflection in article 3. 6. 10 shall

govern in the design of composite beams. Where the beams are not provided with falsework or support during the placing of the concrete slab,the deflection due to the slab and other permanent dead loads added beforethe slab concrete sets, shall be computed without composite beam action.

3. 9. 6.—Shear Devices.Mechanical means which are used at the junction of beam and slab for

the purpose of furnishing the shear resistance necessary to produce com

posite beam action shall conform to the specifications of the respectivematerials as provided in division 4. The shear devices shall be of suchconstruction as will permit a thorough compaction of the concrete mass andwill insure entire surfaces of shear devices being in contact with surroundingconcrete.

The nature of the shear devices shall be such as to prevent a verticalseparation of the slab and beams or else additional means shall be providedfor this purpose.

SECTION 10—Sectional Plate Pipe

3. 10. 1.—General.The material for sectional plate pipe shall conform to division IV, and

the construction shall conform to division II. The minimum gage shall beaccording to the following tables or as otherwise specified herein. The pipeshall be according to table 1, if strutted, or table 2, if unstrutted. Unlessunstrutted pipe is called for on the plans or by special provisions, thestrutted pipe shall be used.

3. 10. 2.—Gage of Side and Top Plates.

(For live load not to exceed H20 or H20-S16)

Sectional Plate Pipe

Strutted Pipe

TABLE I

Height of Cover in Feet Diameter of Pipe, in Inches

60 75 90 105 120 135 150 165 180

2 to 5. inclusive 10 10 10 8 8 7 7 5 56 to 10, inclusive 10 10 10 8 8 7 5 5 3

11 to 15, inclusive 10 10 8 8 7 5 5 3 316 to 20, inclusive 10 10 8 7 5 5 3 3 121 to 25, inclusive-. 10 10 8 7 5 3 3 126 to SO, inclusive 10 8 8 5 S 3 1 131 to 35, inclusive 10 8 7 5 3 3 136 to 40, inclusive 10 8 7 5 341 to 45, Inclusive 8 7 5 346 to 50, inclusive 8 7 5 351 to 55, Inclusive . 8 5 356 to 60, Inclusive 7 561 to 70, inclusive 5 371 to 80, Inclusive 3

DESIGN 206

UnstruttedTABLE 2

Height of Cover in Feet

2 to 5f inclusive6 to 10, inclusive

11 to 15, inclusive16 to 20, inclusive21 to 25, inclusive26 to 80, inclusive31 to 85, inclusive36 to 40, inclusive41 to 45, inclusive46 to 50, inclusive51 to 55, inclusive56 to 60, inclusive61 to 70, inclusive71 to 80, inclusive

Diameter of Pipe, in Inches

60 75 90 105 120 135 150 165 180

10 10* 10* 10* 8* 7* 5* 5* 3*10 10 8 7* 5 3 3* 1*8 8 7 5 3 18 7 5 3 18 5 3 17 5 15 3 15 85 13 13 16

1 (1

* Gage shown with (*) to be used only when there is to be no live load over pipe. If the pipe is tocarry live load use strutted pipe as given in table 1.

3. 10. 3.—Minimum Height of Cover.

The height of cover, measured from finished grade to the top of thepipe shall be not less than 2 feet.

3. 10. 4.—Gage of Bottom Plate*.For pipes having a lighter gage than one, the bottom plates shall have

the next heavier gage shown in the gage table, unless otherwise providedby special provisions or by notes on the plans. The additional metal isprovided to resist abrasion.

3. 10. S.—Bolts.Not less than four bolts shall be used per foot of longitudinal seam.

If the culvert is to be placed under greater height of cover than given intable 1, the bolts shall be increased in number as specified in article 3. 10. 6.Where ends are skewed, not less than iVie inch hook bolts at 12-inch centersshall be used to anchor the plates to headwalls.

3. 10. 6.—Cover Exceeding Heights Specified in Table 1.

The height of cover for strutted culverts, given in table 1, may be

increased 50 per cent providing that the number of bolts used per foot oflongitudinal seam is increased by 50 per cent and the minimum gage usedis No. 1.

3. 10. 7.—Sizes of Pipe not in Tables.

For sizes of pipe which are between those in the tables, the gage shallbe interpolated where possible, otherwise the gage of the next larger sizeshall be used.

3. 10. 8.—Multiple Pipes.

Where multiple lines of pipe are installed, the adjacent sides shall be

at least one-half diameter apart up to 4 feet to permit careful tamping ofthe filling material.

3. 10. 9.—Strutting.

When strutted pipe is specified, the strutting shall be done as specifiedin division II.

206 HIGHWAY BRIDGES

SECTION 1 1—Sectional Plate Arches

3. 11. 1.—General.

The material for arches shall conform to division IV, and the construction shall conform to division II. The minimum gage shall be according tothe following table.

3. 11. 2.— Gages for Sectional Plate Arches.

H-10 Lire Load H-15 Live Load H-20 Live Load

Span Height of Cover Height of Cover Height of Cover

I V V t y 0' 7' V V 10' 2' 3' 4' 5' 6' V tt 9" If 2' 3' 4' S' V r r V If

10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10

r 10 M 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10V 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 8 10 10 10 10 10 10 10 10V M 10 10 10 10 10 10 10 10 8 10 10 10 10 10 10 10 10 7 8 10 10 10 10 10 10 10

w 10 10 10 10 10 10 10 10 10 7 8 10 10 10 10 10 10 10 7 8 10 10 10 10 10 10 8w 8 10 10 M 10 10 10 8 8 7 8 10 10 10 10 10 8 8 7 7 8 8 10 10 8 8 8ir S 10 10 10 10 10 8 8 7 7 7 8 8 10 8 8 7 7 5 7 7 7 8 8 8 7 7

13' 7 8 10 10 10 8 8 7 5 5 7 7 8 8 8 7 7 s 3 5 7 7 7 7 7 5 514' 7 7 1 s s 8 7 s 3 5 7 7 7 7 7 5 5 3 1 3 5 5 7 7 5 3 315' 7 7 7 7 7 7 S 3 3 3 5 5 7 7 5 5 3 I 1 3 5 5 5 3 3 116' 7 7 7 7 7 7 5 3 1 1 3 5 5 7 5 3 1 1 3 5 3 1 1

17' i 7 7 7 7 s 3 1 1 1 3 5 5 3 1 1 3 118' s 5 7 7 7 5 1 I 3 3 5 3 I 119' 5 6 6 5 8 3 1 1 1 3 1

20" .1 3 5 i 5 3 1 1w 1 3 3 3 5 I22' 1 1 3 3 3 1

23' 1 l 1 324' l 1 1

Ri*e3. 11.3 Ratio

Span

The designs of the arches given in the table are based on ratios ofrise to span varying from .2 to .5 inclusive except as provided in article3. 11. 5.

3. 11. 4.—Minimum Height of Cover.

The height of cover, measured from finished grade to the top of thearch shall be not less than 2 feet of earth alone ; or 18 inches of earth undera flexible type pavement; or 6 inches of earth under a rigid type pavement.

3. 11. 5.—Adjustment of Table.

In case the ratio of rise to span is less than .3, in combination with aheight of cover of 3 feet or less, the gage of the plates shall be the nextheavier than required by the table and those for which number one gageis specified shall not be used.

3. 11. 6.—Bolts.

Not less than four bolts shall be used per foot of longitudinal seam.

DESIGN 207

3. 11. 7.—Skewed Spans and Multiple Arches.

The skew shall not exceed 45°. When the skew is more than 15° thelength of the structure shall be such that no portion of the live load willbe carried by the cut portion of the arch end. Where right of way or otherconditions do not permit the required length the cut end shall be supportedby a rigid headwall designed to meet the conditions. The plates shall be

anchored to the headwall with not less than H/ig-inch hooked bolts at notover 12-inch centers.

Where mutiple arch spans are used the distance between plates atskewback shall be not less than of the longer adjoining span.

3. 11. 8.—Substructure Design.

The substructure shall be designed according to specifications hereinfor substructures of bridges.

SECTION 12—Rating of Existing Bridges

3. 12. 1.—General.

The specifications set forth in this section shall be used in determiningthe rating of existing structures for inventory purposes and for determining the safe live load capacity of existing structures.

3. 12. 2.—Inventory Ratings.

The inventory rating shall be a classification of existing bridges interms of the standard H loadings. The inventory rating shall be determined as follows:

(1) The load-carrying value of each member, connection, or part ofthe structure shall be determined in accordance with the unit workingstresses and design procedure set forth in the design division of thesespecifications. In this determination, due consideration shall be given todeterioration of material, loss of section, type of material, and physicalcondition as shown by field examination. Where dimensions of membersare outside the limits for which design formulae are applicable, the procedure set up in articles which follow shall be used.

(2) The dead load stress in each member and connection of the structure shall be determined.

(3) The difference between the load-carrying value and the dead loadstress gives the stress capacity available for live load and impact.

(4) The live load stress in each member and connection under thestandard H-15 loading, with suitable impact factor, is computed.

(5) The available stress capacity, (3), divided by the H-15 live loadand impact stress, (4), gives a factor which when multiplied by 15 is theinventory or H rating of the member or connection.

The inventory rating of the structure is the rating of the weakestmember or connection.

3. 12. 3.—Operating Rating.

The operating rating is the safe load-carrying capacity of the structureand is to be used in determining the maximum loads which may be permitted to pass over the structure. It is intended that structures requiringload limitations shall be kept in service only long enough to permit replacement or repair and that during such period frequent inspections are to be

made. Under these conditions, unit working stresses 1% times the design

208 HIGHWAY BRIDGES

stresses given in section 4 of this division or IV2 times the stresses asreduced in article 3. 12. 7 may be permitted. This limitation shall apply tometal, concrete, and timber.

3. 12. 4.—Dead Load.

The dead load on the structure shall consist of the weight of the structure plus any attachments thereto. It shall be determined by actual fieldinspection. The unit weights shall be assumed to be those set forth inarticle 3. 2. 2.

3. 12. 5.—Live Load.

The live load used in establishing the inventory or H rating shallbe the H loading with impact as given in article 3. 2. 5. The live load usedin establishing the operating rating shall be the actual vehicle size andtype using the highway, together with an impact factor dependent on localconditions, and will vary from time to time and from state to state inaccordance with local laws or regulations. Probable sidewalk loads alsoshall be considered.

3. 12. 6.—Minimum Wind Load.

The minimum wind load provision of paragraphs (2) and (3), article3. 2. 14. shall not apply in the calculations for operating rating.

3. 12. 7.—Unit Stresses.

The unit working stresses used in determining the load-carrying capacity of each member of a structure shall take into account the type ofmaterial from which the member is made. The unit working stress assumedfor the inventory rating shall not exceed 0.545 of the yield point and for theoperating rating shall not exceed 0.82 of the yield point. Where informationconcerning the specification under which the metal was supplied is not available, it will be assumed that the yield point does not exceed 30,000 poundsper square inch for all bridges built after 1905. Bridges built previous to thisyear shall be checked to see that the material is not of a fibrous nature. Ifit is fibrous or of doubtful character, the yield point will be assumed to be

equal to that of wrought iron which shall be taken as 26,000 pounds persquare inch. In the absence of definite information, it shall be assumed thatthe yield point of wrought iron is 26,000 pounds per square inch, and theunit working stress shall be taken as 14,000 pounds per square inch.

The provisions of this section apply to material with a yield point of33,000 pounds per square inch, unless otherwise noted.

3. 12. 8 Traffic Lanes.

The lane loadings or truck loadings shall be considered to occupy lanes,each having a width of 10 feet for bridges of over 20 feet in width. Forbridges having a roadway width of at least 16 feet but less than 20 feet, thevehicle shall be considered to occupy half of the available roadway. Onstructures having a roadway width of less than 16 feet, a maximum loadlane 10 feet in width shall be placed so as to give the maximum stress in themember under consideration.

3. 12. 9.—Allowable Stresses (Columns loaded concentrically or eccentrically)

The permissible unit stress in all concentrically loaded columns as wellas those with known eccentricity of loading shall be as specified in appendix

DESIGN 209

B, except that, where they apply, the approximate formulas given inarticles 3. 4. 2, 3. 4. 7 and 3. 4. 8 may be used.

The value of the factor of safety "n," as specified in appendix B shallbe used for the inventory rating of structures but only seventy-nine percent (79%) of the values shown therein shall be used for operating ratings.

3. 12. 10.—Batten Plate Columns.

To allow for the reduced strength of batten plate columns, the actuallength of the column shall be increased by the following factor to obtainthe value of L/r to be substituted in the formulae given in article 3. 4. 2

or 3. 12. 9.

Actual Spacing center to center of batten plates

L/r Up to 2d 4d 6d lOd

40 1.3 2.0 2.8 4.580 1.1 1.3 1.7 2.3

120 1.0 1.2 1.3 1.8160 1.0 1.1 1.2 1.5200 1.0 1.0 1.1 1.3

d = width of member perpendicular to battens.

For columns having a solid plate on one side and batten plates on the other,the foregoing increase factors shall be reduced 50 per cent.

3. 12. 11.—Compression on Flanges of Beams and Girders.

Compression in the extreme fiber of rolled shapes, girders, and builtsections subject to bending when the value L/b is less than 40 shall belimited to the value given by the formula in article 3. 4. 2. For such members whose L/b ratio exceeds 40, the maximum stress shall be limited tothe value given by the following formula:

k

where p = allowable compressive unit stressL = distance in inches between points of definite lateral supportb= flange width of beam or girder in inchesk = 18,000 for inventory ratingk = 27,000 for operating rating

In determining "L" in the above formula, it can be assumed that well-seatedand properly-bearing timber stringers furnish adequate lateral support.

3. 12. 12.—Details of Design.

(a) Strength of Connections.

For the purpose of rating, connections having a capacity equal to thestress in the member connected shall be considered adequate.

(b) Splices.

For compression splices with milled ends in contact, 70 per centof the stress may be considered to be taken in bearing, in which case,splice plates and rivets with a capacity equal to 30 per cent of the stressacross the splice shall be considered adequate. For the purposes of rating

210 HIGHWAY BRIDGES

structures lug angles and shelf angles shall be considered effective incarrying stress.

(c) Pins.

For the purpose of rating, the stress in the outer fiber of pins need

not be computed unless the lever arm of the couple producing the momentis greater than the diameter of the pin.

3. 12. 13.—Field Inspection.

As a basis for the rating of existing structures, adequate informationas to the dimensions and condition of the members in the structure shallbe provided by competent field inspection. The data provided shall includeline diagrams showing lengths and positions of all members, detailed dimensions of all members and connections, supplemented by sketches as necessary; detailed information as to the condition of the material showing reduced sections due to deterioration, accident, or other cause; and any otherpertinent information that will aid in the intelligent evaluation of thestructure. The field inspection shall be made under the direction of a

thoroughly trained and competent engineer who should be familiar withall phases of bridge design and construction.

DIVISION IV

Materials *

SECTION I—Cement

4. 1. 1.—General.

The portland cements recognized by these specifications are of fivetypes which are designated as follows:

Type I. For use in general concrete construction when the specialproperties specified for types II, III, IV, and V are not required.

Type II. For use in general concrete construction exposed to moderatesulfate action or where moderate heat of hydration is required.

Type III. For use when high early strength is required.Type IV. For use when a low heat of hydration is required. (Note)Type V. For use when high sulfate resistance is required. (Note)

Note. —Attention is called to the fact that cements conforming to therequirements for type IV and type V are not usually carried in stock. Inadvance of specifying their use purchasers or their representatives shoulddetermine whether these types of cement are, or can be made, available.

Cement of the type specified shall conform to the Specifications forPortland Cement of the A. A. S. H. 0., Designation: M 85-48. Unlessotherwise provided, or called for in the special provisions, type 1 cementshall be furnished.

4. 1. 2.—Sampling and Testing.

Portland cement shall be sampled and tested in accordance with the"Standard Methods of Sampling and Testing Highway Materials," American Association of State Highway Officials.

Cement may be sampled either at the mill or at the site of the work asprovided in the above specification. The seals of cars containing cementwhich has been sampled shall not be broken except by the engineer; otherwise additional samples shall be taken from these cars.

The contractor shall notify the engineer of dates of delivery so thatthere will be sufficient time for sampling the cement, either at the mill orupon delivery. If this is not done or if additional tests are necessary, thecontractor may be required to rehandle the cement in the storehouse forthe purpose of obtaining the required samples.

SECTION 2—Water For Use With Cement

4. 2. 1.—Quality.

Water for use with cement in mortar or concrete shall be subject tothe approval of the engineer. It shall not be salt or brackish and shall be

reasonably clear and free from oil, acid, injurious alkali or vegetable matter.

4. 2. 2 Tests.

When required by the engineer the quality of the mixing water shall be

determined by the Standard Method of Test for Quality of Water to be

Used in Concrete of the A. A. S. H. O. Methods of Sampling and Testing,Designation: T 26-35.

* Note: Also refer to division 1, Section 6, for "Control of Materials" and to article 1. 6. 2regarding amendments and revisions to the A. A. S. H. O. and A. S. T. M. Specificationsfor Materials and Testing:.

211

212 HIGHWAY BRIDGES

In sampling; water for testing, care shall be taken that the containersare clean and that samples are representative.

When comparative tests are made with a water of known satisfactoryquality, any indication of unsoundness, marked change in time of setting, ora reduction of more than 10 per cent in mortar strength, shall be sufficientcause for rejection of the water under test.

SECTION 3—Fine Aggregate

4. 3. 1.—Fine Aggregate.

All fine aggregate for concrete shall conform to the Specification forPine Aggregate for Portland Cement Concrete of the A. A. S. H. 0. Specifications for Highway Materials, Designation: M 6-48. Note: Requirementsfor soundess should be stipulated in the special provisions (Refer to A. A.5. H. O., Designation: M 6-48, 4 (a), (b) and (c)).

4. 3. 2.—Sand for Mortar.

Sand for mortar shall conform to the Specifications for Mortar Sand ofthe A. A. S. H. 0. Specifications for Highway Materials, Designation:M 46-42.

SECTION A—Coarse Aggregates

4. 4. 1.—Coarse Aggregates.

All coarse aggregates for concrete shall conform to the Specificationfor Coarse Aggregate for Portland Cement Concrete of the A. A. S. H. 0.Specifications for Highway Materials, Designation: M 80-42. Note: Requirements for soundness should be stipulated in the special provisions (referto A. A. S. H. O., Designation: M 80-42, 6 (a), (b), (c)).

Slag shall be used for aggregate only if its use is provided for in thespecial provisions.

4. 4. 2.—Rubble or Cyclopean Aggregate.

One-man and derrick stone used in rubble or cyclopean concrete shallconsist of tough, sound and durable rock. The stone shall be free fromcoatings, drys, seams or flaws of any character. In general, the percentageof wear shall be not greater than 6 per cent as determined by StandardMethod of Test for Abrasion of Stone and Slag by use of the Deval Machine of the A. A. S. H. 0. Methods of Sampling and Testing, Designation :

T 3-35.Preferably, stone shall be angular in shape and shall have a rough

surface such as will thoroughly bond with the surrounding mortar.

SECTION 5—Reinforcement

4. 5. 1.—Bar Reinforcement.Bar reinforcement for concrete shall conform to the requirements of the

Specification for Billet Steel Bars for Concrete Reinforcement of the A. A.5. H. O. Specifications for Highway Materials, Designation: M 31-48 withthe following modifications:

(1) All bars shall be of the deformed type unless otherwise specified.

MATERIALS 213

(2) The use of cold twisted bars not permitted.

(3) All bars shall be either "Structural Steel Grade" or "IntermediateGrade," open hearth process, unless otherwise called for in the specialprovisions or on the plans.

(4) The type of deformation shall be subject to the approval of theengineer.

In addition to the above requirements the deformation of deformedbars shall conform to the Minimum Requirements for the Deformation ofDeformed Steel Bars for Concrete Reinforcement, of the A. A. S. H. O.Specifications for Highway Materials, Designation: M 137-48 (A. S. T. M.Designation: A 305-47T).

4. 5. 2.—Wire and Wire Mesh.

Wire shall conform to the Specification for Cold-Drawn Steel Wire forConcrete Reinforcement, of the A. A. S. H. O. Specifications for HighwayMaterials, Designation: M 32-42 (A. S. T. M. Designation: A 82-34).

Wire mesh, when used as reinforcement in concrete shall conformto the Specification for Welded Steel Wire Fabric for Concrete Reinforcement of the A. A. S. H. 0. Specifications for Highway Materials,Designation: M 55-37 (A. S. T. M. Desigination : A 185-37). The type ofmesh shall be approved by the engineer.

4. 5. 3.—Bar Mat Reinforcement.Bar mat reinforcement for concrete shall conform to the Specification

for Fabricated Steel Bar or Rod Mats for Concrete Reinforcement of theA. A. S. H. O. Specification for Highway Materials, Designation: M 54-37

(A. S. T. M. Designation: A 184-37).

4. 5, 4.—Structural Shapes.

Structural shapes used as reinforcement in concrete shall conform to

the requirements for structural steel as provided in these specifications.

SECTION 6—Structural, Eyebar and Rivet Steels

4. 6. 1.—General.

Steel shall be furnished according to the following specifications,supplemented by the additional requirements of articles 4. 6. 9. to 4. 6. 14.,

inclusive. Unless otherwise specified, structural carbon steel (4.6.2) andstructural rivet steel (4. 6. 6) shall be furnished.

4. 6. 2.—Structural Carbon Steel and Eye Bar Steel.

Structural carbon steel shall conform to the Specification for Steel forBridges and Buildings of the A. S. T. M., Designation: A 7-46.

Steel for eye bars shall conform to the Specifications for Steel forBridges and Buildings of the A. S. T. M. Designation: A 7-39.

4. 6. 3.—Structural Silicon Steel.

Structural silicon steel shall conform to the Specification for Structural Silicon Steel of the A. S. T. M. Designation: A 94-46.

4. 6. 4.—Structural Low-Alloy Steel.

Structural low-alloy steel shall conform to the Specification for Low-Alloy Steel of the A. S. T. M. Designation: A 242-46.

214 HIGHWAY BRIDGES

4. 6. 5.—Structural Nickel Steel.

Structural nickel steel shall conform to the Specifications for StructuralNickel Steel of the A. S. T. M. Designation: A 8-46.

4. 6. 6.—Structural Rivet Steel.

Structural rivet steel shall conform to the Specification for StructuralRivet Steel of the A. A. S. H. O. Specifications for Highway Materials,Designation: M 97-39 (A. S. T. M. Designation: A 141-39).

4. 6. 7.—High-strength Structural Rivet Steel.

High-strength structural rivet steel shall conform to the Specificationfor High-Strength Structural Rivet Steel of the A. A. S. H. 0. Specifications for Highway Materials, Designation: M 98-41 (A. S. T. M. Designation: A 195-41).

4. 6. 8.—Copper Bearing Steels.

When copper bearing steel is specified, the steel shall contain not lessthan 0.2 per cent of copper.

4. 6. 9 Full Size Tests.

When full-size tests of built-up structural members and eyebars arerequired by the contract, the contractor shall supply testing machines ofthe proper type and capacity and shall provide all facilities and laborincidental to the making of tests. In all tests involving the determinationof tensile and compressive strengths, the ultimate strength, deformationand other pertinent data shall be recorded.

4. 6. 10.—Number and Size of Test Bars.

When tests of full-sized eyebars are required, the number and size ofthe bars to be tested shall be designated by the engineer before the millorder is placed. The number shall not exceed 5 per cent of the wholenumber of bars ordered, with a minimum of two bars on small orders.

4. 6. 11 Selection of Test Bars.

Test bars shall be of the same section as the bars to be used in thestructure and of the same length if within the capacity of the testingmachine. They shall be selected by the inspector from the finished bars,preferably after annealing. Test bars representing bars too long for thetesting machine shall be selected from the full-length bar material afterthe heads on one end have been formed and shall have the second headformed upon them after being cut to the greatest length which can be

tested.

4. 6. 12.—Failure to Meet Requirements.

If an eyebar fails to fulfill the specified requirements, two additionalbars of the same size and from the same melt shall be tested. The barsrepresented by the test may be reannealed before the additional bars aretested.

If two of the three test bars fail to give satisfactory results, the barsof that size and melt shall be rejected.

4. 6. 13.—Record of Annealing.

A record of the annealing charges shall be furnished the engineershowing the bars included in each charge and the treatment they received.

MATERIALS 215

4. 6. 14.—Payments for Full-Size Tests.

Any full-size member tested to destruction shall be paid for by thepurchaser at the unit contract price, if the test proves satisfactory. If thetest proves the member to be unsatisfactory, the members represented byit will be rejected. The expense of conducting tests shall be borne by thecontractor unless otherwise provided.

SECTION 7—Wrought Iron

4. 7. 1.—Wrought-Iron Plates.

Wrought-Iron Plates shall conform to the Specification for Wrought-Iron Plates of the A. S. T. M. Designation : A 42-47.

4. 7. 2.—Rolled Wrought-Iron Shapes and Bars.

Rolled Wrought-Iron Shapes and Bars shall conform to the Specification for Rolled Wrought-Iron Shapes and Bars of the A. A. S. H. 0.Specifications for Highway Materials, Designation: M 100-39 (A. S. T. M.Designation: A 207-39).

4. 7. 3.—Welded Wrought-Iron Pipe

Welded Wrought-Iron Pipe shall conform to the Specification forWelded Wrought-Iron Pipe of the A. S. T. M. Designation: A 72-45.

SECTION 8—Steel Forgings

4. 8. 1.—Carbon Steel Forgings.

Steel Forgings shall conform to the Specifications for Carbon-SteelForgings for General Industrial Use of the A. S. T. M. Designation:A 235-46. Class C 1 forgings shall be furnished unless otherwise specified.

SECTION 9—Steel Castings

4. 9. 1.—Carbon Steel Castings.

Carbon Steel Castings shall conform to the Specification for mild tomedium-strength, carbon-steel castings for general application of theA. S. T. M. Designation: A 27-46T. Grade 65-35 shall be furnishedunless otherwise specified.

4. 9. 2.—Chromium Alloy-Steel Castings.

Chromium Alloy-Steel Castings shall conform to the Specification forChromium Alloy-Steel Castings of the A. S. T. M. Designation : A 296-46T.Grade 10 shall be furnished unless otherwise specified.

SECTION 10—Gray-Iron Castings

4. 10. 1.—Gray Iron Castings.

Gray iron castings shall conform to the specification for Gray IronCastings of the A. S. T. M. Designation: A 48-46. Class No. 30 shall be

furnished unless otherwise specified.

216 HIGHWAY BRIDGES

4. 10. 2.—Workmanship and Finish.

Iron castings shall be true to pattern in form and dimensions, freefrom pouring faults, sponginess, cracks, blow holes, and other defects inposition affecting their strength and value for the service intended.

Castings shall be boldly filleted at angles and the arrises shall be sharpand perfect.

4. 10. 3.—Cleaning.

All castings must be sandblasted or otherwise effectively cleaned ofscale and sand so as to present a smooth, clean, and uniform surface.

SECTION II— Malleable Castings

4.11. 1.—Malleable Castings.

Malleable castings shall conform to the Specification for MalleableIron Castings of the A. S. T. M. Designation: A 47-47. Grade No. 35018shall be furnished unless otherwise specified.

4. 11.2. —Workmanship 'and Finish.

Malleable castings shall be true to pattern in form and dimensions,free from pouring faults, sponginess, cracks, blow holes, and other defects inpositions affecting their strength and value for the service intended.

The castings shall be boldly filleted at angles and the arrises shall besharp and perfect. The surfaces shall have a workmanlike finish.

4. 11. 3.—Cleaning.

All castings must be sandblasted or otherwise effectively cleaned ofscale and sand so as to present a smooth, clean, and uniform surface.

SECTION 12—Bronze or Copper-Alloy Bearing and Expansion Plates

4. 12 1.—Bronze Bearing and Expansion Plates.

Bronze bearing and expansion plates shall conform to the Specificationfor Bronze Castings for Turntables and Moveable Bridges and for Bearingand Expansion Plates of Fixed Bridges of the A. S. T. M. Designation:B 22-46T. Class B shall be furnished unless otherwise specified.

4. 12. 2.—Rolled Copper-Alloy Bearings and Expansion Plates.Rolled copper-alloy bearing and expansion plates shall conform to the

Specification for Rolled Copper-Alloy Bearing and Expansion Plates forBridge and Other Structural Uses of the A. S. T. M. Designation: B 100-

46. Type A shall be furnished unless otherwise specified.

SECTION 13—Steel Piles

4. 13. 1.—Steel Piles.Steel piles shall consist of structural steel shapes of the section pro

vided on the plans or as otherwise specified. The steel shall conform tothe Specification for Steel for Bridges and Buildings of the A. S. T. M.Designation A 7-46.

MATERIALS 217

SECTION 14—Steel Sheet Piling

4. 14. 1.—Process.

The steel shall be made by the open hearth process.

4. 14. 2.—Chemical Composition

The steel shall conform to the following requirements as to chemicalcomposition :

Phosphorus not over 0.06 per cent.Sulphur not over 0.06 per cent.Copper, when copper steel is specified, not less than 0.20 per cent.

4. 14.3. —Physical Properties.

The steel shall conform to the following requirements as to physicalproperties :

Tensile strength, minimum, pounds per square inch 70,000

1,400,000Elongation in 8 inches, minimum, per cent

tensile strength

A minimum tensile strength of 60,000 pounds per square inch shall be

permitted for piling used in the fabrication of corners, tees, etc.

4. 14. 4.—Bend Tests.

Bend test specimens shall stand being bent cold through 180" arounda pin, the diameter of which is equal to twice the thickness of the specimen,without cracking on the outside of the bent portion.

4. 14. 5.—Miscellaneous Requirements.

All piling shall conform in other respects —test specimens, number oftests, finish, marking and inspection —to the requirements of the Specifications for Steel for Bridges and Buildings of the A. S. T. M. Designation:A 7-46.

SECTION 15—Steel Grid Floors

4. 15. 1 Steel.

All steel shall conform to the Specification for Steel for Bridges andBuildings of the A. S. T. M. Designation: A 7-46. Unless the materialis galvanized, it shall have a copper content of 0.2 per cent.

4. I5. 2.—Protective Treatment (Shop Coat).Open type floors, preferably, shall be galvanized in accordance with the

Specification for Zinc (Hot-Galvanized) Coatings on Structural Steel Shapes,Plates and Bars, and their Products of the A. S. T. M. Designation: A123-47.

In lien of galvanizing the floor may be painted if specified in the specialprovisions. The paint shall be applied according to the specifications forPainting Metal Structures, except that dipping will be permitted. The paintshall be as specified for metal structures unless paint of other type isrequired by the special provisions.

218 HIGHWAY BRIDGES

4. I5. 3.—Concrete.

All concrete in filled steel grid floors shall conform to the specificationfor concrete, division II. The concrete and the size of aggregate shall beas specified for Class Y concrete, division II.

SECTION 16—Paint

Paint for Timber Structures

4. 16. 1.—Paint for Timber Structures.

Paint for timber structures, except as otherwise provided herein, shallconform to the Specification for White and Tinted Ready-Mixed Paint (Leadand Zinc Base) of the A. A. S. H. 0. Specifications for Highway Materials,Designation: M 70-42. The paint as specified is intended for use in covering previously painted surfaces. When it is applied to unpainted timber,turpentine and linseed oil shall be added as required by the character ofthe surface in an amount not to exceed one pint each per gallon of thepaint as specified. The paint shall be either white or tinted as directedby the engineer.

If aluminum or black paint is specified the first or prime coat shallbe as specified above. The paint for additional coats shall be as follows :

(a) Aluminum Paint.Aluminum paint shall conform to the Specification for Aluminum Paint

(Paste-Mixing Vehicle) of the A. A. S. H. O. Specifications for HighwayMaterials, Designation: M 69-48.

(b) Black Paint.( 1 ) Composition.

Maximum Minimumper cent per cent

Pigment 32 28Liquid (containing at least 80 per cent linseed

oil) 72 68Water 0.5Coarse particles and "skins" (total residue re

tained on No. 325 sieve based on pigment) . . 1.5

Weight per gallon, not lass than 9.0 lbs.

(2) Pigment.

The pigment in both semipaste and ready-mixed paints shall consistof carbon, lead oxide, insoluble mineral material, and, at the option of themanufacturer, oxide of iron. The pigment shall show on analysis not lessthan 20 per cent of carbon and not less than 5 per cent of lead oxide calculated as PbaQj. (Since oxide of lead may be dissolved by the oil in paint,in all cases when the amount of lead in the pigment calculated as Pb304is found to be less than 5 per cent of the pigment, lead should be determinedin the vehicle and the total lead in the paint computed to percentage ofpigment.) The total of the lead oxide, iron oxide, insoluble mineral material,and loss on ignition shall be not less than 90 per cent.

(3) Vehicle.The liquid in semipaste paint shall be entirely linseed oil; in ready-

mixed paint it shall contain not less than 80 per cent of linseed oil, thebalance to be combined drier and thinner. The thinner shall be turpentine,volatile mineral spirits, or a mixture thereof.

MATERIALS 219

(4) Ready-Mixed Paint.Unless otherwise authorized by the engineer the paint shall be "ready-

mixed" (factory-mixed).Ready-mixed paint shall be well-ground, shall not settle badly or cake

in the container, shall be readily broken up with a paddle to a smoothuniform paint of good brushing consistency, and shall dry within 18 houreto a full oil gloss, without streaking, running, or sagging. The color anuhiding power when specified shall be equal to those of a sample mutuallyagreed upon by buyer and seller.

(5) Methods of Analysis.Paint shall be analyzed in accordance with methods given in Federal

Specifications Nos. TT-P-141a and TT-P-27.

Paint for Metals

4. 16. 2.—Shop Coat (Prime Coat).The shop or prime coat of paint for metal shall be a red lead paint

and shall conform to the Specification for Red Lead (Dry and Paste-in-Oil)and Paint Made Therefrom, Designation: M 71-42 or to the Specificationfor Red Lead Ready-Mixed Paint, Designation: M 72-48 of the A. A. S. H. O.

Specifications for Highway Materials. Note: If a mixture of raw andboiled linseed oil is desired, the percentages of each kind shall be stipulatedin the special provisions. Refer to footnote of A. A. S. H. 0., Designation:M 71-42, article 5 (a).

The paint, preferably, shall be factory mixed. As an alternative thepigment shall be furnished in the form of red lead paste.

4.16.3.—First Field Coat.When the finish coat of paint is specified to be aluminum, black or

graphite paint, or colored green, brown or dark gray, the first field coatshall be a red lead paint as specified for the shop coat, tinted light brownas required, with lamp black in an amount not to exceed % pound per gallonof linseed oil.

When the finish coat is to be white or gray, a first field coat conformingto the Specification for White and Tinted Ready-Mixed Paint (Lead andZinc Base) of the A. A. S. H. O. Specifications for Highway Materials,Designation: M 70-42 may be used in lieu of red lead paint. The paintshall be tinted as directed by the engineer.

4.16.4. —Second Field Coat. (Finish Coat.)

(a) General.

The paint to be used for the second field coat shall be as requiredby the special provisions or as noted on the plans. It shall conform toone of the following specification3 :

(1) Green Graphite Bridge Paint (refer to (b)).(2) Black Bridge Paint, Designation (refer to (c)).(3) Aluminum Paint (Paste-Mixing Vehicle), Designation: M 69-48.(4) White and Tinted Ready-Mixed Paint (Lead and Zinc Base), Desig

nation: M 70-42.(5) Red Lead (Dry and Paste-in-Oil) and Paint made therefrom, Desig

nation: M 71-42.

(6) Red Lead Ready-Mixed Paint, Designation: M 72-48.

If red lead is used for the second field coat it shall be tinted withlampblack as directed by the engineer.

220 HIGHWAY BRIDGES

(b) Green Graphite Bridge Paint.

Scope

1. These specifications cover linseed oil green ready-mixed paintfor bridges.

General Requirements

2. The paint shall be well-ground, shall not settle badly or cake inthe container, shall be readily broken up with a paddle to a smooth uniformpaint of good brushing consistency, and shall dry to a full-oil gloss without streaking, running or sagging when applied to a vertical surface. Theshade and hiding power shall be that which may be specified in the contract.

Pigment

3. (a) The pigment shall consist of graphitic carbon, chrome green,red lead and insoluble siliceous mineral matter. The chrome green shallbe a mixture of prussian blue and chrome yellow. The pigment shall showon analysis not more than 50 per cent siliceous pigment and not less than10 per cent graphitic carbon. The red lead calculated as PbsCU shall notbe less than 20 per cent by weight of the pigment. Since oxide of leadmay be dissolved by the oil in the paint, in all cases when the amount oflead in the pigment, calculated as PbsCt, is found to be less than 20 percent of the pigment, lead shall be determined in the vehicle and the totallead (as PbsCU) in the paint computed to percentage of pigment. The leadto be calculated as PbsC^ shall not include the lead in the lead chromate.

(b) The materials used in the preparation of the pigment shall conformto the requirements given in the following:

Graphite.

1. The material required shall contain at least 82 per cent ofgraphitic carbon and shall be free from grit, dirt, or any otherdeleterious substance.

General Requirements.

2. The general requirements' shall be as stated in the followingparagraph.

Detail Requirements.

3. (a) Amorphous graphite shall be ground to such fineness that100 per cent will pass through a No. 20 bolting cloth.

(b) The graphite shall not lose more than 3 per cent in weightwhen tested for ignition, as required in paragraph 4 (c).

Method of Inspection and Tests.

4. (a) Samples from each lot submitted for inspection shall be

obtained for chemical analysis.(b) A sufficient amount of material shall be tested for fineness

as required in paragraph 3 (a).(c) A one-gram sample of the amorphous graphite shall be taken

to represent each lot and shall be dried for one hour at 110° C., thenplaced in a tightly covered 30 cubic centimeter capacity platinum crucible and heated for 30 seconds over the full flame of a Bunsen gas burner.The difference in weight, between the dried material immediately

MATERIALS 221

before submitting to the Bunsen flame and after being heated andcooled, shall be taken as ignition loss referred to in paragraph 3 (b).Chrome green A. A. S. H. O. Designation: M 130-42

Red lead A. A. S. H. O. Designation: M 71-42

Vehicle

4. (a) The liquid or vehicle in the paint shall contain not less than80 per cent of raw linseed oil and the balance to be combined thinner anddryer. The thinner shall be turpentine, volatile mineral spirits or a

mixture thereof.

(If desired the raw linseed oil may be wholly or partially replacedwith boiled oil. The desired percentage shall be stated in the contract.)

(b) The materials used in the preparation of the vehicle shallconform to the requirements given in the following specifications:

Raw linseed oil A. A. S. H. 0. Designation : M 125-42Boiled linseed oil A. A. S. H. O. Designation: M 126-42Turpentine A. A. S. H. O. Designation: M 127-42Mineral spirits A. A. S. H. O. Designation : M 128-42Drier Federal Specification TT-D 651a

Composition

5. The paint shall conform to the following requirements:

Maximum Minimumper cent per cent



tained on No. 325 sieve) 1.5

Drying Time

6. When applied in a normal brushing coat the paint shall dry hardand tough in not more than 24 hours, under normal conditions of temperature and humidity.

Weight

7. The weight per gallon at 77° F. shall not be less than 11 pounds.

Packing and Marking

8. Paint shall be delivered in such containers as may be specified inthe .contract. Each container shall bear a label with the followinginformation shown thereon: name and address of the manufacturer andcontractor, shipping point, trade mark or trade name, kind of paint, formula,number of gallons, date and lot number.

Methods of Analysis

9. Paint shall be analyzed in accordance with the methods given inFederal Specification No. TT-P-141a and TT-P-27.

(c) Black Bridge Paint.Scope

1. These specifications cover linseed oil black ready-mixed paint forbridges.

222 HIGHWAY BRIDGES

General Requirements

2. The paint shall be well-ground, shall not settle badly or cake inthe container, shall be readily broken up with a paddle to a smooth uniformpaint of good brushing consistency, and shall dry to a full oil gloss without streaking, running or sagging when applied to a vertical surface. Thecovering or hiding power shall be that which may be specified in the contract.

Pigment

3. (a) The pigment shall consist of gaphitic carbon, red lead, ironoxide and insoluble siliceous mineral matter. The pigment shall show onanalysis not less than 35 per cent carbon and 20 per cent lead oxide,calculated as Pb304. Since some oxide of lead may be dissolved by the oilin the paint, in all cases when the amount of lead in the pigment, calculatedas PbsO-i, is found to be less than 20 per cent of the pigment, lead shallbe determined in the vehicle and the total lead (as PbsGj) in the paintcomputed to percentage of pigment. The total of the lead oxide, ironoxide, insoluble mineral matter and loss on ignition shall not be less than90 per cent.

(b) The materials used in the preparation of the pigment shallconform to the requirements given in the following:

Graphite.

1. The material required shall contain at least 82 per cent ofgraphitic carbon and shall be free from grit, dirt, or any otherdeleterious substance.

General Requirements.

2. The general requirements shall be as stated in the followingparagraph.

Detail Requirements.

S. (a) Amorphous graphite shall be ground to such fineness that100 per cent will pass through a No. 20 bolting cloth.

(b) The graphite shall not lose more than 3 per cent in weightwhen tested for ignition, as required in paragraph 4 (c).

Method of Inspection and Tests.

h. (a) Samples from each lot submitted for inspection shall be

obtained for chemical analysis.

(b) A sufficient amount of material shall be tested for finenessas required in paragraph 3 (a).

(c) A one-gram sample of the amorphous graphite shall be takento represent each lot and shall be dried for one hour at 110°C., thenplaced in a tightly covered 30 cubic centimeter capacity platinumcrucible and heated for 30 seconds over the full flame of a Bunsengas burner. The difference in weight, between the dried materialimmediately before submitting to the Bunsen flame and after beingheated and cooled, shall be taken as ignition loss referred to inparagraph 3 (b).

Red lead A. A. S. H. O. Designation: M 71-42Iron oxide A. A. S. H. O. Designation : M 129-42

MATERIALS 223

Vehicle

4. (a) Liquid. — The liquid or vehicle in the paint shall contain notless than 80 per cent of raw linseed oil and the balance to be combineddryer and thinner. The thinner shall be turpentine, volatile mineralspirits, or a mixture thereof.

(If desired, the raw linseed oil may be replaced with boiled oil tothe extent of 50 per cent of the total oil content. The desired percentageshall be stated in the contract.)

(b) The materials used in the preparation of the vehicle shallconform to the requirements given in the following specifications :

Raw linseed oil A. A. S. H. 0. Designation : M 125-42Boiled linseed oil A. A. S. H. 0. Designation : M 126-42Turpentine A. A. S. H. 0. Designation : M 127-42Mineral spirits A. A. S. H. O. Designation : M 128-42Drier Federal Specification TT-D 651a

Composition

5. The paint shall consist of:Maximum Minimumper cent per cent



tained on No. 325 sieve) 1.6

Drying Time

6. When applied in a normal brushing coat the paint shall dry innot more than 24 hours, under normal conditions of temperature andhumidity.

Weight

7. The weight per gallon at 77° F. shall not be less than 9% pounds.

Packing and Marking

8. Paint shall be delivered in such containers as may be specifiedin the contract. Each container shall bear a label with the followinginformation shown thereon: name and address of the manufacturer andcontractor, shipping point, trade mark or trade name, kind of paint,formula, number of gallons, date and lot number.

Methods of Analysis

9. Paint shall be analyzed in accordance with the methods given inFederal Specifications Nos. TT-P-141a and TT-P-27.

SECTION 17— Welding

4. 17. 1.—Welding Materials.

Materials used for welding shall conform to the Specifications forWelded Highway and Railway Bridges of the American Welding Society.

224 HIGHWAY BRIDGES

SECTION 18—Sheet Metal for Water Stops and General Use

4. 18. 1.—Sheet Copper. •

Sheet copper shall conform to the Specifications for Copper Sheet,Strip and Plate, of the A. A. S. H. O. Specifications for Highway Materials,Designation: M 138-48 (A. S. T. M. Designation: B 152-46 T). Type Ashall be used unless otherwise specified.

4. 18. 2.—Sheet Lead.

Sheet lead shall conform to the requirements for Common DesilverizedLead A, of the Specification for Pig Lead of the A. A. S. H. O. Specificationsfor Highway Materials, Designation: M 112-45 (A. S. T. M. Designation:B 29-43).

4.18.3 Sheet Zinc

Sheet zinc shall conform to the requirements for Type II of theSpecifications for Rolled Zinc of the A. A. S. H. 0. Specifications forHighway Materials, Designation: M 113-39 (A. S. T. M. Designation:B 69-39).

SECTION 19—Sectional Plate Pipe and Arches

4. 19. 1.— General.

Plates shall be fabricated from base metal made by the open hearthprocess. The base metal shall conform to one of the following chemicalrequirements :

Elements

Chemical Composition(Position of base metals does not indicate preference)

Kind of Base Metal Tolerances

CopperBearing

PureIron

CopperMolybdenumIron

GenuineWrought

Iron

Carbon, maximum %

PureIron

CopperIron

CopperSteel

.05 .01Manganese, maximum %

.bis .bis .bis.06.12.04.15

.01Phosphorus, maximum % .015

.040 .040

.20

.040

.20

.040

.40

.050

.20

.biSilicon, maximum %Copper, minimum .02Molybdenum, minimum %Sum of first 5 elements,

maximum % .10 .25

.05

.25 .70 .42 .04Sum of first 6 elements,

maximum % .10 .... .04

NOTE — These requirements conform to the Specification for Corrugated Metal CulvertPipe of the A. A. S. H. O. Specifications for Highway Materials, Designation: M 36-42.

4. 19. 2.—Spelter Coating.

A coating of prime western spelter or equal shall be applied by the

hot-dip process at the rate given below per square foot of double-exposed

surface.

Pipe 60 to 120 inches in diameter (inclusive) and arches:

8 to 10 gage, incl., 2 oz.1 to 7 gage, incl., 3 oz.

Pipe 135 to 180 inches in diameter (inclusive), 3 oz.

MATERIALS 225

If the average spelter coating as determined from the required samplesis less than the amount specified above, or if any one specimen shows adeficiency of 0.2 ounce where a 2-ounce coating is specified, or a deficiencyof 0.3 ounce in the case of a 3-ounce coating requirement, the lot sampledshall be rejected. Spelter coating shall be of first-class commercial quality,free from injurious defects, such as blisters, flux and uncoated spots.

4. 19. 3.—Galvanising.

All pipe and arches for which 3-ounce spelter is required shall btgalvanized after fabrication. When gages No. 8 and lighter are used, themetal may be galvanized either before or after fabrication.

4. 19. 4.—Sampling.

For testing weight of spelter coating and for chemical analysis of basemetal, when required, a sample approximately 3 inches square, or a sampleof equivalent area, shall be cut from the corner of one plate in each 100

plates of a shipment or fraction thereof.

4.19. S.—Chemical Analysis and Tests for Spelter Coating.

When required, the chemical analyses of base metal shall be made inaccordance with A. S. T. M. Specification E 30-45.

The test for weight of spelter coating shall be made in accordance withA. A. S. H. O. Standard Method T 65-42, or A. S. T. M. Designation: A90-39.

4. 19. 6.—Certified Analysis and Guarantee.

The manufacturer of the base metal shall file with the engineer a

certificate setting forth the name or brand of metal to be furnished and

a typical analysis showing the percentage of carbon, manganese, phosphorus, sulphur, silicon and copper; also molybdenum, when provided forunder the particular kind of base metal. The certificate shall be sworn to forthe manufacturer by a person having legal authority to bind the company.

The manufacturer shall include in the certificate a guarantee providingthat all metal furnished shall conform to requirements of that particularbase metal as set forth in section 4. 19. 1, shall bear a suitable identificationbrand or mark, and shall be replaced without cost to the purchaser whennot in conformity with the specified analysis, gage, or spelter coating, the

cost to be limited to the replacement of sectional plate material only; and

the guarantee shall be so worded as to remain in effect so long as themanufacturer continues to furnish material.

One brand, and one brand only, shall be approved for each kind of base

metal furnished by each of the actual manufacturers of the base metal.

4. 19. 7.—Identification.No plates will be accepted unless the metal is identified by a stamp on

each plate showing:

(1) Name of base metal manufacturer.(2) Name of brand and kind of base metal.

(3) Gage number.

(4) Weight of spelter coating.

The identification brands shall be so placed that when the pipe or arch

is erected the indentification will appear on the inside of the structure.

(5) Identification symbols showing S heat number

I pot number

226 HIGHWAY BRIDGES

4.19.8.—Bolts (for Connecting Plates).Bolts for connecting plates shall be not less than uAe inch in diameter,

and shall be hot-dip galvanized. The threads shall be American NationalCoarse Thread Series, Class 2 fit.

They shall meet the following physical test requirements:

Minimum tensile strength 110,000# per sq. in.Minimum shear 80,000# per sq. in.Minimum reduction of area 35 per centBrinell hardness between the limits 241-286

The tests shall be made on finished bolts. Unless otherwise authorized,the bolts shall be furnished so they may be sampled and tested beforeerection is commenced.

4. 19. 9.—Nuts and Bolt Heads.

Bolt heads and nuts shall be special designed to provide even anduniform bearing on the curved corrugated surfaces, or special washersshall be used in lieu thereof.

4. 19. 10.—Corrugations.

Corrugations shall have a pitch of 6 inches with a tolerance of M inchand a depth of at least 1 % inches, with a tolerance of plus or minus % inch.

4. 19. 11.—Gage Determination and Tolerance.

Where mill or factory inspection is employed, gage shall be determinedby weight of flat plates before corrugating. Theoretical weights andtolerances shall be as follows:

Theoreticalwt. before

galvanizing(Lbs./sq. ft.)

Theoretical

Gagewt. after

galvanizing(Lbs./sq. ft.)

Permissible variation in ave. wt. oflots* (in per cent)

Over Under1 11.25 11.438 4 SS 10.00 10.188 4 3S 8.75 8.938 4.5 S7 7.50 7.688 4.5 88 6.875 7.031 5 5

10 5.625 5.781 5 5

* The term "lot" means all the plates of one gage in the shipment, for gages 7 andheavier, and not less than 6,000 pounds constitutes a "lot" for gages 8 and lighter. Individual plates shall not underrun the theoretical weights by more than 10 per cent.

4. 19. 12.—Field Inspection and Acceptance of Plates.

The field inspection shall be made by the engineer, who shall be furnished with an itemized statement of the number and length of the platesin each shipment by the manufacturer.

Each plate included in a shipment shall fully meet the requirementsof these specifications; and if 25 per cent of the plates in any shipment failto meet the requirements the entire shipment may be rejected.

SECTION 20— Stone for Masonry

4. 20. 1 Ashlar Stone.

Stone for ashlar masonry shall be of the kind specified on the plans orin the contract. The stone shall be tough, dense, sound and durable, resistant to weathering action, reasonably fine grained, uniform in color, and

MATERIALS 227

free from seams, cracks, pyrite inclusions, or other structural defects.Preferably, stone shall be from a quarry the product of which is knownto be of satisfactory quality. Stone shall be of such character that it canbe wrought to such lines and surfaces, whether curved or plane, as maybe required. Any stone having defects which have been repaired withcement or other materials shall be rejected.

Each bidder shall submit with his bid a 6-inch cubical block of thestone he proposes to furnish and shall designate the quarry from which itis obtained. The quality of the stone furnished shall be at least equal tothat of the sample. The sample shall be squared and dressed on threesides; one side shall be smooth-finished, one side fine-finished, and one sideshall be given the finish indicated on the plans for exposed surfaces offace stone. The remaining sides shall be left with quarry face. (Fordefinitions of surface finishes of stone, see "Ashlar Masonry," division II.)

When permitted by the engineer, bidders may submit bids, accompaniedby samples as specified above, on kinds of stone other than that specified.

4. 20. 2.—Rubble Stone.

Stone for mortar rubble or dry rubble masonry shall be of approvedquality, sound and durable, and free from segregations, seams, cracks, andother structural defects or imperfections tending to destroy its resistanceto the weather. It shall be free from rounded, worn, or weathered surfaces.All weathered stone shall be rejected.

4.20. 3.—Riprap.

Stone for riprap shall consist of field stone or rough, unhewn quarrystone as nearly rectangular in section as is practicable. The stone shallbe dense, resistant to the action of air and water, and suitable in all otherrespects for the purpose intended.

SECTION 21— Brick

4. 21. 1.—Paving Brick.

Brick to be used in the wearing surface of bridge floors shall conformto the Specification for Paving Brick of the A. A. S. H. O. Specification forHighway Materials, Designation: M 40-42.

4. 21. 2.—Brick for Masonry.

Brick for masonry construction shall conform to the Specification forBuilding Brick (made from clay or shale) of the A. A. S. H. 0. Specificationsfor Highway Materials, Designation: M 114-41. The grade of brickto be furnished shall be as specified in the special provisions.

The brick shall have a fine-grained, uniform, and dense structure, freefrom lumps of lime, laminations, cracks, checks, soluble salts, or otherdefects which may in any way impair their strength, durability, appearance,or usefulness for the purpose intended. Bricks shall emit a clear, metallicring when struck with a hammer.

SECTION 22—Bituminous Materials and Joint Fillers

4. 22. 1.—Oil Asphalt Fillers.

The filler shall be Type A or Type B, as specified in the special provisions or on the plans.

228 HIGHWAY BRIDGES

Type A.Asphalt filler for brick wearing surfaces and poured expansion joints

shall conform to the Specification for Oil Asphalt Filler of the A. A. S. H. O.Specifications for Highway Materials, Designation: M 18-42.

Type B.The filler shall consist of:

80 to 85 parts of asphalt cement15 to 20 parts of mineral filler.

The asphalt cement shall conform to the Specification for AsphaltCement of the A. A. S. H. 0. Specifications for Highway Materials, Designation: M 20-42.

The mineral filler shall all pass a No. 200 sieve and 95 to 100 per centshall pass a No. 325 sieve.

This blend of asphalt and mineral filler shall show a per cent of fillerin the lower portion not more than 10 per cent greater than the averagefiller content of the blend, when the blend is maintained at a temperatureof 325° for two hours without agitation. The blend shall meet the following requirements:

Penetration at 77° F 40 +Ductility at 77° F 20 cms. +Inorganic material insoluble in carbon disulphide. . 15 to 26% by weightTest —Loss on heating at 325°, 5 hours 2% —

4. 22. 2.—Premolded Expansion Joint Fillers.

Non-extruding and resilient types shall conform to the Specificationfor Preformed Expansion Joint Fillers for Concrete of the A. A. S. H. O.Specifications for Highway Materials, Designation: M 58-42.

Bituminous fiber types shall conform to the specification for PreformedExpansion Joint Filler for Concrete of the A. A. S. H. O. Specificationsfor Highway Materials, Designation: M 59-42.

Bituminous type filler shall conform to the Specification for PreformedExpansion Joint Filler for Concrete of the A. A. S. H. O. Specificationsfor Highway Materials, Designation: M 33-42.

Bituminous Carpets

4. 22. 3.—Tar.

The first or prime coat (cold application) for tar carpets, on concretejr wood bridge floors, shall be a homogeneous tar conforming to the Specifications for Highway Materials, Designation : M 52-42, Grade RT-2. GradesRT-1, RT-3 or RT-4 may be used when designated by the engineer.

The second coat (hot application) shall be Grade RT-8 or RT-9. Thegrade to be used, dependent on local conditions, shall be designated by theengineer.

4. 22. 4.—Asphalt.

For the first or prime coat (cold application) for either mixed orpenetration asphalt carpets, asphalts Type MC or RC shall be used. If the

surfaces are lean or absorbent, asphalt Type MC-0 or MC-1 (A. A S. H. O.Designation: M 82-42) shall be used. If the surfaces are well compacted

or nonabsorbent, asphalt Type RC-0 or RC-1 (A. A. S. H. O. Designation :

M 81-42) shall be used. For heavier prime coats than those obtainable with

MATERIALS 229

the aforementioned materials, asphalts Type MC-2 or RC-2 may be used.If the use of heat is necessary for the satisfactory application of thesematerials, the application of such heat shall be done cautiously.

The second coat (hot application) for asphalt carpets on concrete orwood bridge floors shall be either Type RC-3, RC-4, or RC-5 (A. A. S. H. O.Designation: M 81-42) or an asphaltic emulsion (A. A. S. H. O. Designation: M 48-42, M 49-42, M 50-42, or M 51-42). The grade used shall be

specified by the engineer in accordance with local conditions. The heatingof the asphalts Type RC shall be done with caution.

Waterproofing Materials4. 22. 5.—Asphalt.

Waterproofing asphalt shall conform to the specification for asphaltfor damp-proofing and water-proofing of the A. A. S. H. O. Specificationsfor Highway Materials, Designation: M 115-42. Note: Type A is for useabove ground and Type B for use below ground. Unless otherwise specified, Type B shall be used.

Primer for use with asphalt in waterproofing shall conform to theSpecification for Primer for Use with Asphalt in Damp-proofing and Waterproofing of the A. A. S. H. O. Specification for Highway Materials, Designation: M 116-42 (A. S. T. M. Designation: D 41-41).

4. 22. 6 Pitch.

Waterproofing pitch shall conform to the Specification for Coal-tarPitch for Roofing, Damp-proofing and Waterproofing of the A. A. S. H. 0.Specification for Highway Materials, Designation: M 118-42. Type B

pitch shall be furnished unless otherwise specified.Primer for use with coal-tar pitch in damp-proofing and waterproofing

shall conform to the Specification for Creosote for Priming Coat withCoal-tar Pitch in Damp-proofing and Waterproofing of the A. A. S. H. 0.Specifications for Highway Materials, Designation: M 121-42 (A. S. T. M.Designation: D 43-41).

4. 22. 7.—Fabric.

The fabric shall conform to the Specification for Woven Cotton FabricsSaturated with Bituminous Substances for Use in Waterproofing of theA. A. S. H. O. Specifications for Highway Materials, Designation: M 117-40.

4. 22. 8.—Tar for Absorptive Treatment.

Tar for absorptive treatment shall be a liquid water-gas tar whichconforms to the following requirements: «

Specific gravity, 25°/25° C. (77°/77° F.) 1.030 to 1.100Specific viscosity at 40° C. (104° F.) (Engler), not

more than 3.0Total distillate, per cent by weight, to 300° C. (572°

F.), not more than 50.0Bitumen (soluble in carbon disulphide), not less than,

per cent 98.0Water, not more than, per cent 3.0

4.22.9 Tar Seal Coat.

Tar seal coat shall conform to the Specification for Tar for Use inRoad Construction of the A. A. S. H. O. Specifications for HighwayMaterials, Designation: M 52-42, Grade RTCB-5.

230 HIGHWAY BRIDGES

4. 22. 10 Joint Fillers.

Filler for use in horizontal joints in waterproofing work shall be a

straight refined oil asphalt conforming to the following requirements:

(1) Flash point: Not less than 232° C. (450° F.).(2) Softening point: 48.9° C. (120° F.) to 54.4° C. (130° F.).(3) Penetration: At 0° C. (32° F.), 200 grams, 1 minute, not less than 15.

At 25° C. (77° F.), 100 grams, 5 seconds, 50 to 60.At 46° C. (115° F.), 50 grams, 5 seconds, not more than 300.

(4) Loss on heating: At 163° C. (325° F.), 50 grams, 5 hours, not morethan 0.5 per cent.

(5) Ductility: At 25° C. (77° F.), 5 centimeters per minute, not less than 85.

(6) Total bitumen (soluble in carbon disulphide): Not less than 99.5per cent.

Filler for use in vertical joints in waterproofing work shall be anasphalt conforming to the requirements specified above for horizontal jointfiller, to which has been added 20 per cent by weight, of asbestos fiber.The incorporation of the asbestos fiber with the asphalt shall be done atthe factory of the manufacturer to insure a uniform distribution of thefiber throughout the mix.

4. 22. 11.—Inspection and Delivery.

All waterproofing materials shall be tested before shipment. Unlessotherwise ordered by the engineer, they shall be tested at the place ofmanufacture, and, when so tested, a copy of the test results shall be sentto the engineer by the chemist or inspection bureau which has been designated to make the tests, and each package shall have affixed to it a label,seal, or other mark of identification, showing that it has been tested andfound acceptable, and identifying the package with the laboratory tests.

Factory inspection is preferred, but, in lieu thereof, the engineer mayorder that representative samples, properly identified, be sent to him fortest prior to shipment of the materials. After delivery of the materials,representative check samples shall be taken which shall determine theacceptability of the materials.

All materials shall be delivered on the work in original containers,plainly marked with the manufacturer's brand or label.

SECTION 23— Asphalt Paving Blocks4. 23. 1.—General.

Asphalt blocks shall be composed of asphaltic cement, mineral aggregate and inorganic dust, as herein specified, thoroughly mixed while hotin such proportions that the finished blocks shall conform to the specifiedrequirements. v

The ingredients of the blocks shall be tested in accordance with themethods provided in the Standard Methods of Sampling and Testing ofthe American Association of State Highway Officials.

Each bidder shall submit with his bid a specimen block of the size andquality described in these specifications, labeled with the name of the bidder,the name of the manufacturer, and the place of manufacture. Bids notaccompanied by specimen blocks will not be accepted.

4. 23. 2.—Asphaltic Cement.

The asphaltic cement shall conform to the following requirements:

(1) It shalllbe homogeneous and free from water.(2) Specificvgravity 25°/25° C. (77°/77° F.), not less than 1.00.

MATERIALS 231

(3) Flash point: Not less than 190° C. (374° F.).(4) The penetration at 25° C. (77° F.), 100 grams, 5 seconds, shall be

varied to suit climatic and traffic conditions in accordance with thefollowing table:

Temperature

Traffic Low Moderate High

Light 15-25 15-25 10-15Moderate 15-25 15-20 10-15Heavy 15-20 10-20 5-15

(5) Loss on heating: At 163° C. (325° F.), 50 grams, 5 hours, notmore than 2.0 per cent.

(6) Penetration of residue after heating: At 25° C. (77° F.), 100grams, 5 seconds, as compared to penetration before heating,not less than 50 per cent.

Ductility: At 25° C. (77° F.), 5 to 10.Proportion of bitumen soluble in carbon tetrachloride: Not less

than 99.0 per cent.(8)

4. 23. 3.—Mineral Aggregate.

The mineral aggregate shall be clean, hard, unweathered trap rock,dolomite, limestone, copper conglomerate, or other suitable material whichshall show a percentage of wear of not more than 5 per cent. Its gradingshall be such as to produce, with the inorganic dust, the granulometriccomposition hereinafter . specified.

4. 23. 4.—Inorganic Dust.

The inorganic dust, or filler, shall be produced from sound limestoneor other approved material and shall be powdered to such a fineness that95 per cent shall pass a 30-mesh sieve and not less than 50 per cent shallpass a 200-mesh sieve. Sufficient inorganic dust shall be used to give thegranulometric composition hereinafter specified.

4. 23. 5.—Manufacture.Before being mixed, the asphaltic cement and crushed mineral aggre

gate shall be heated separately. In no case shall either be heated to ahigher temperature than 350° F. but the temperature of each shall be soregulated that the temperature of the mixture as delivered to the pressmoulds shall be not less than 225" F.

The mineral aggregate, inorganic dust and asphaltic cement in theproper proportions shall be thoroughly mixed to produce a homogeneousmass in which all particles are thoroughly coated with asphaltic cement.

The blocks shall receive a compression in the moulds of not less than4,000 pounds per square inch, applied on the 3-inch by 12-inch surface.After pressing, they shall be cooled by passing through water or by othersuitable means.

4. 23. 6.—Physical Characteristics.

(a) Size and Shape.

The blocks shall be 5 inches in width by 12 inches in length unless thedepth required is less than 2 inches, in which case they shall be 4 inches inwidth by 8 inches in length. The depth shall be as shown on the plans.A variation either way from these dimensions of Vl inch in length or % inchin width or depth will be sufficient cause for rejection of any block.

232 HIGHWAY BRIDGES

(b) Composition.

The composition of the blocks, as delivered on the work, shall be asfollows:

Mineral matter:Retained by Ji-inch screen (circular openings), not more than 10 per cent.Passing J£-inch screen and retained by 20-mesh sieve, 30 to 60 per cent.Passing 20-mesh sieve and retained by 100-mesh sieve, 15 to 35 per cent.Passing 100-mesh sieve (including all fines), 20 to 40 per cent.Passing 200-mesh sieve, not less than 15 per cent.Asphaltic cement, 6J£ to 9 per cent.Specific gravity: The blocks shall have a specific gravity of not less than

2.35 at 77° F.

(c) Absorption Test.

The blocks to be tested shall be cleaned of loose particles, carefullyweighed, placed in a pressure vessel and subjected to a vacuum of 22 inchesfor one hour at room temperature. While still maintaining the vacuum,water shall then be admitted to the vessel until the blocks are completelyimmersed, after which the vacuum shall be relieved and water pressurecarried up to 100 pounds per square inch and there maintained for onehour. The blocks shall then be removed from the vessel and, after moppingoff all surface water, shall be carefully weighed. The average of a set offour blocks tested in this manner shall not show an absorption exceeding0.3 per cent by weight.

4. 24. 1.— General.

Premolded asphalt plank shall conform to the Specification for Pre-molded Asphalt Plank of the A. A. S. H. O. Specifications for HighwayMaterials, Designation: M 46-38. Type (a) Plain Asphalt Plank andType (b) Mineral Surfaced Asphalt Plank shall be furnished as specifiedin the special provisions or as noted on the plans.

4. 25. 1.—Species of Woods.

The common and botanical names of the species of woods recognizedin these specifications are described as follows:

SECTION 24— Premolded Asphalt Plank

SECTION 25—Structural Timber, Lumber and Piling

Common Name Botanical NameCedar, Northern WhiteCedar, Port OrfordCedar, Western RedChestnutCypress, Tidewater RedFir, Douglas (Coast)Fir, Douglas (Inland)

Thuja occidentalisChamaecyparis lawsonianaThuja plicataCastanea dentataTaxodium distichumPseudotsuga taxifolia (Coast)Pseudotsuga taxifolia

Gum, BlackHemlock, EasternHemlock, West CoastLarch, WesternOak, Red, includes:

(Inter-mountain type)Nyssa sylvaticaTsuga canadensisTsuga heterophyllaLarix occidentalis

Red Oak

Black Oak

Quercus borealis andQuercus borealis maxima

MATERIALS 233

Common Name

Southern Red OakWater OakWillow OakScarlet OakPin OakShumard Red OakSwamp Red OakBlackjack OakLaurel OakTexas Red Oak

Oak, White, includes:White OakChestnut OakPost OakBur OakOvercup OakSwamp Chestnut OakSwamp White OakLive OakChinquapin Oak

Pine, Idaho WhitePine, LodgepolePine, Northern WhitePine, NorwayPine, PondorosaPine, Southern Yellow, includes:

Loblolly PineLongleaf PinePitch PinePond PineShortleaf PineSlash Pine

Pine, SugarRedwoodSpruce, Eastern, includes:

Black SpruceRed SpruceWhite Spruce

Spruce, Engelmann, includes :Engelmann SpruceBlue Spruce

Spruce, SitkaTamarack

Botanical Name

Quercus rubraQuercus nigraQuercus phellosQuercus coccineaQuercus palustrisQuercus shumardiiQuercus rubra pagodaefoliaQuercus marilandicaQuercus laurifoliaQuercus texana

Quercus albaQuercus montanaQuercus stelataQuercus macrocarpaQuercus lyrataQuercus prinusQuercus tricolorQuercus virginianaQuercus muehlenbergiiPinus monticolaPinus contortaPinus strobusPinus resinosaPinus ponderosa

Pinus taedaPinus palustrisPinus rigidaPinus serotinaPinus echinataPinus caribaeaPinus lambertianaSequoia sempervirens

Picea marianaPicea rubraPicea glauca

Picea engelmanniPicea parryanaPicea sitchensisLarix laricina

4. 25. 2.—Limitation of Use.

Timbers of the following species shall not be used in exposed structureswithout preservative treatment:

Red oaks; black gum; hemlock; shortleaf, loblolly, pond, Idaho white,Ponderosa, and sugar pines ; and all spruces.

4. 25. 3.—Grading of Yard Lumber.Yard lumber shall be graded in accordance with grading rules, adopted

by regional associations of lumber manufacturers, which conform to thebasic provisions of the "American Lumber Standards."

Lumber ordered in multiple lengths shall be graded after being cutto length.

4. 25. 4.—Hewn and Round Timbers.Hewn timbers used in place of sawed timbers shall conform in all

respects to the grading rules for structural timber.

234 HIGHWAY BRIDGES

Round timbers used in place of sawed timbers shall be of a qualityequal to that hereinafter specified for timber piles. The effective size ofa round timber shall be considered the same as that of a square timberhaving sectional dimensions equal to those of the inscribed square of theround timber at the critical section.

Hewn and round timbers shall not be used except when specified orapproved by the engineer.

Grading of Structural Timber4. 25. 5.—General.

Structural timber used as a permanent part of a structure shall begraded, for the grade selected, in accordance with the grading rules adoptedby the regional association of the lumber manufacturers which conform tothe basic provisions of the "American Lumber Standards."

(a) Grade of Timber.The grade to be used shall be as specified in article 2. 20. 1 or as

modified in the special provisions or as shown on the plans.

(b) Commercial Grading Rules.In referring to commercial grading rules the following shall be

stipulated :

(1) The name of the association.

(2) The year of issue of the grading rules referred to.

(3) The paragraph number.

(4) The stress grade selected.

(5) The species.

(6) Whether rough, dressed or extent of dressing.

(7) Square edge, if wane is not permitted (usually special grade).(8) Any heartwood requirements (refer to article 4. 25. 6).

The material supplied according to the Commercial Grading Rulesshall be of equal or greater stress value than the stress grade specified.


There shall be no heartwood requirement for timber that is to be

pressure treated and the amount of sapwood shall not be limited.It is generally considered advisable to specify a minimum heartwood

requirement for untreated structural timbers. Also it is considered advisable to specify sidecut material for stringers, floor beams and caps. Ifeither of these provisions are adopted, definite requirements shall be

stipulated in the special provisions or on the plans.

Timber Piles4. 25. 7.—General.

Timber piles which will be below water level at all times may be ofany species of wood which will satisfactorily withstand driving.

In untreated piling for use in exposed work, the diameter of theheartwood at the butt shall be not less than $io of the required diameterof the piles.

4. 25. 8.—Quality.

All piling shall be cut from sound trees and shall be free from anydefects which might impair their strength or durability. Pieces showingdecay or attack by grubs, worms or borers will not be accepted. Fire-killed

MATERIALS 235

trees will be accepted provided the sapwood has not been charred. Pilingshall contain no unsound knots. Sound knots will be permitted providedthe diameter of the knot does not exceed 4 inches or % of the diameterof the stick at the point where it occurs. Any defects or combination ofdefects which will impair the strength of the pile more than the maximumallowable knot shall not be permitted. The butts shall be sawed square,and the tips shall be sawed square or tapered to a point not less than4 inches in diameter, as directed by the engineer.

Unless otherwise specified, all piles shall be peeled by removing all ofthe rough bark and at least 80 per cent of the inner bark. No strip ofinner bark remaining on the stick shall be over % inch wide and thereshall be at least 1 inch of clean wood surface between any two such strips.Not less than 80 per cent of the surface of any circumference shall beclean wood.

Piles shall be cut above the ground swell and shall taper from butt totip. A line drawn from the center of the tip to the center of the butt shallnot fall outside of the center of the pile at any point more than 1 per centof the length of the pile. In short bends, the distance from the center ofthe pile to a line stretched from the center of the pile above the bend tothe center of the pile below the bend shall not exceed 4 per cent of thelength of the bend or a maximum of 2% inches. All knots shall be trimmedclose to the body of the pile.

4. 25. 9.—Dimensions.

Round piles shall have a minimum diameter at the tip, measured underthe bark, as follows:

Length of pile Tip diameter

Less than 40 feet 8 inches40 to 60 feet 7 inchesOver 60 feet 6 inches

The minimum diameter of piles at a section 3 feet from the butt,measured under the bark, shall be as follows:

Diameter in inchesDouglas fir, All other

Length of pile southern yellow pine species

20 feet and under 11 11

21 to 30 feet 12 12

31 to 40 feet 12 13

Over 40 feet 13 14

The diameter of the pile at the butt shall not exceed 20 inches. Thediameter of a pile in cases where the tree is not exactly round shall be

determined either by measuring the circumference and dividing the numberof inches by 3.14, or by taking the average of the maximum and minimumdiameters at the location specified.

Square piles shall have the dimensions shown on the plans.

SECTION 26—Timber Preservatives

4. 26. 1.—Preservatives.

Timber preservatives shall conform to the Specification for TimberPreservatives of the A. A. S. H. O. Specifications for Highway Materials,Designation: M 133-42.

The type of preservative furnished shall be in accordance with thatspecified in the special provisions or as noted on the plans.

236 HIGHWAY BRIDGES

SECTION 27— Timber Connectors

4. 27. 1.—General.

Reference is made to article 2. 20. 2, Timber Connectors. Connectorsfor treated timber structures, except those of malleable iron, shall be

galvanized in accordance with A. S. T. M. Designation: A 123-47.

4. 27. 2.—Split Ring Connectors.

Split rings of 2% -inch inside diameter, 4-inch inside diameter and6-inch inside diameter shall be manufactured from hot rolled, low-carbonsteel conforming to A. S. T. M. Standard Specifications for Carbon-Steel Blooms, Billets, and Slabs for forgings, Designation: A 273-47T,Grade 1015. Each ring shall form a closed true circle with an outsidecylindrical surface parallel to the axis of the ring. The inside surface,except for the 6-inch ring, shall be beveled from the median line towardthe edges. It shall be cut through in one place in its circumference toform a tongue and slot.

Connector grooves in timber shall be cut concentric with the bolt holeand shall be of the following dimensions:

For 2% -inch split-rings — inside diameter, 2.56 inches; width of groove,0.18 inch; depth of groove, 0.37 inch.

For 4-inch split-rings — inside diameter, 4.08 inches; width of groove,0.21 inch; depth of groove, 0.50 inch.

For 6-inch split-rings — inside diameter, 6.12 inches; width of groove,0.27 inch; depth of groove, 0.62 inch.

4. 27. 3.—Tooth-Ring Connectors.

Toothed-ring timber connectors shall be stamped cold from U. S.

Standard 16-gage hot rolled sheet steel conforming to A. S. T. M. StandardSpecifications for Carbon-Steel Blooms, Billets, and Slabs for forgings, Designation: A 273-47T, Grade 1015, and shall be bent cold to form a circular,corrugated, sharp-toothed band and circle and shall be parallel to the axisof the ring. The central band shall be welded to fully develop the strengthof the band. All sizes, 2-inch, 2% -inch, 3% -inch and 4-inch diameters, shall

have an over-all depth of .94 inch and a depth of fillet of .25 inch.

4. 27. 4.—Shear Plate Connectors.

Pressed Steel Type. Pressed steel shear-plates of 2% -inch diameter

shall be manufactured from mild steel conforming to A. S. T. M. StandardSpecifications for Carbon-Steel Blooms, Billets, and Slabs for forgings, Designation: A 273-47T, Grade 1015. Each plate shall be a true circle with aflange around the edge, extending at right angles to the face of the plateand extending from one face only, the plate portion having a central bolthole and two small perforations on opposite sides of the hole and midwayfrom the center and circumference.

Malleable Iron Type. Malleable iron shear-plates of 4-inch diametershall be manufactured according to A. A. S. H. O. M 106-35 (A. S. T. M.A 47-47), Grade No. 35018, for malleable iron castings. Each casting shallconsist of a perforated round plate with a flange around the edge extendingat right angles to the face of the plate and projecting from one face only,the plate portion having a central bolt hole reamed to size with an integralhub concentric to the bolt hole and extending from the same face as theflange.

MATERIALS 237

4.27.5, —Clan-Plate Connectors.

Claw-plate timber connectors of 2% -inch, 3% -inch and 4-inch diameters,

shall be malleable iron castings, manufactured acording to A. A. S. H. O.M 106-35 (A. S. T. M. A. 47-47), Grade No. 35018. Each claw-plate shall consist of a perforated circular flanged plate with three-sided teeth arrangedabout the perimeter of one face. The male plate shall have integral cylindrical hubs on both faces concentric to a bolt hole through the center of theplate. The female plate shall be flat on the side opposite the teeth but shallhave an integral cylindrical hub concentric to the central bolt hole and onthe face with the teeth.

4. 27. 6.—Spike-Grid Connectors.

Spike-grid timber connectors shall be manufactured according toA. A. S. H. O. M. 106-35 (A. S. T. M. A. 47-47), Grade No. 35018, formalleable iron castings. They shall consist of four rows of opposing spikesforming a 4%-inch square grid with 16 teeth which are held in place byfillets. Fillets for the fiat grid in cross section shall be diamond shaped.Fillets for the single and double curve grids shall be increased in depthto allow for curvature and shall maintain a thickness between the slopingfaces of the fillets equal to the width of the fillet.

APPENDIX A

Loading— H 15-44

Table of Maximum Moments, Shears and Reactions —Simple Spans, One Lane

Spans in feet; moments in thousands of foot-pounds; shears and reactions in thousands of pounds.

These values are subject to specification reduction for loading ofmultiple lanes.

Impact not included.

Span

1...2...8...4...5...

6.7.8.9.

10.

11.12.13.14.15.

Moment6.0 (b)

12.0 (b)18.0 (b)24.0 (b)30.0 (b)

36.0 (b)42.0 (b)48.0 (b)54.0 (b)60.0 (b)

66.0 (b)72.0 (b)78.0 (b)84.0 (b)90.0 (b)

16 96.0 (b)17 102.0 (b)18 108.0 (b)19 114.0 (b)20 120.0 (b)

21 126.0 (b)22 132.0 (b)23 138.0 (b)24 144.0 (b)25 150.0 (b)

26 156.0 (b)27 162.7 (b)28 170.1 (b)29 177.5 (b)30 185.0 (b)

31 192.4 (b)32 199.8 (b)83 207.3 (b)34 214.7 (b)35 222.2 (b)

36 229.6 (b)37 237.1 (b)38 244.5 (b)39 252.0 (b)40 259.5 (b)

load is

Span Moment42 274.4 (b)44 289.3 (b)46 304.3 (b)48 319.2 (b)50 334.2 (b)

52 349.1 (b)54 364.1 (b)56 379.1 (b)58 397.660 418.5

End shearand end

reaction (a)24.0 (b)24.0 (b)24.0 (b)24.0 (b)24.0 (b)

24.0 (b)24.0 (b)24.0 (b)24.0 (b)24.0 (b)

24.0 (b)24.0 (b)24.0 (b)24.0 (b)24.4 (b)

24.8 (b)25.1 (b)25.3 (b)25.6 (b)25.8 (b)

26.0 (b)26.2 (b)26.3 (b)26.5 (b)26.6 (b)

26.8 (b)26.9 (b)27.0 (b)27.1 (b)27.2 (b)

27.3 (b)27.4 (b)27.5 (b)27.727.S

28.128.428.628.929.1

considered placed at the support. Loads used are those

62.64.66.68.70.

75.80.85.90.95.

439.9461.8484.1506.9530.3

590.6654.0720.4789.8862.1

100 937.5110 1,097.3120 1,269.0130 1,452.8140 1,648.5

150 1,856.3160 2,076.0170 2,307.8180 2,551.5190 2.807.3

200 3,075.0220 3,646.5240 4,266.0260 4,933.5280 5,649.0

300 6,412.5

End shearand end

reaction (a)29.630.180.581.081.5

82.032.582.988.488.9

34.484.985.385.886.3

87.588.789.941.142.3

43.545.948.350.758.1

55.557.960.362.765.1

67.572.377.181.986.7

91.5

(a) Concentratedstipulated for shear.

(b) Maximum value determined by Standard Truck Loading.Otherwise the Standard Lane Loading governs.

238

APPENDIX "A" 239

Loading—H 20-44


Spans in feet; moments in thousands of foot-pounds; shears and reac

tions in thousands of pounds.These values are subject to specification reduction for loading of

multiple lanes.Impact not included.

Span1...2...S...4...5...

6.7.8.>.

10.

Moment8.0 (b)

16.0 (b)24.0 (b)22.0 (b)40.0 (b)

48.0 (b)56.0 (b)64.0 (b)72.0 (b)80.0 (b)

11 88.0 (b)12 96.0 (b)18 104.0 (b)14 112.0 (b)15 120.0 (b)

16 128.0 (b)17 186.0 (b)18 144.0 (b)19 152.0 (b)20 160.0 (b)

21 168.0 (b)22 176.0 (b)28 184.0 (b)

\ 24 192.0 (b)25 200.0 (b)

26 208.0 (b)27 216.9 (b)28 226.8 (b)29 286.7 (b)SO 246.6 (b)

21 256.E (b)82 266.5 (b)88 276.4 (b)84 286.8 (b)85 296.2 (b)

86 806.2 (b)87 816.1 (b)88 826.1 (b)29 886.0 (b)40 846.0 (b)

load ie

End shearand end

reaction (a)82.0 (b)32.0 (b)32.0 (b)32.0 (b)82.0 (b)

32.0 (b)32.0 (b)32.0 (b)32.0 (b)82.0 (b)

32.0 (b)82.0 (b)32.0 (b)32.0 (b)32.5 (b)

83.0 (b)83.4 (b)33.8 (b)84.1 (b)34.4 (b)

34.7 (b)34.9 (b)35.1 (b)85.3 r35.5 i

(b)(b)


52 465.5 (b)54 485.5 (b)56 505.4 (b)58 530.160 558.0

62.64.66.68.70.

586.5615.7645.5675.9707.0

75 787.580 872.085 960.590 1,053.095 1,149.5

100 1,250.0110 1,463.0120 1,692.0130 1,937.0140 2,198.0

150 2,475.0160 2,768.0170 8,077.0180 8,402.0190 8.743.0

200 4,100.0220 4,862.0240 5,688.0260 6,578.0280 7,532.0

... 8,550.0

35.7 (b)35.9 (b)36.0 (b)36.1 (b)36.3 (b)

86.4 (b)86.5 (b)86.6 (b)86.987J

87.587.888.288.588.8

considered placed at the support. Loads used are those

800.

End shearand end

reaction (a)39.440.140.741.442.0

42.648.14S.944.645.2

45.846.547.147.848.4

50.051.658.254.856.4

58.061.264.467.670.8

74.077.280.48S.686.8

90.096.4

102.8109.2115.6

122.0

(a) Concentratedstipulated for shear.

(b) Maximum value determined by Standard Truck Loading.Otherwise the Standard Lane Loading: governs.

240 HIGHWAY BRIDGES

Loading— H 15-S 12-44


Spans in feet; moments in thousands of foot-pounds; shears and reactions in thousands of pounds.

These values are subject to specification reduction for loading ofmultiple lanes.

Impact not included.

Span1. ..2...S...4...5...

6.7.8.9.

10.

11.12.13.14.15.

Moment6.0 (b)

12.0 (b)18.0 (b)24.0 (b)80.0 (b)

86.0 (b)42.0 (b)48.0 (b)54.0 (b)60.0 (b)

66.0 (b)72.0 (b)78.0 (b)84.0 (b)90.0 (b)

16 96.0 (b)17 102.0 <b)18 108.0 (b)19 114.0 (b)20 120.0 (b)

21 126.0 (b)22 132.0 (b)23 188.0 (b)24 144.5 (b)25 155.5 (b)

26 166.6 (b)27 177.8 (b)28 189.0 (b)29 200.8 (b)30 211.6 (b)

81 228.0 (b)82 234.4 (b)83 245.8 (b)84 257.7 (b)35 270.9 (b)

86 284.2 (b)87... 297.5 (b)88 310.7 (b)89 324.0 <b)40 337.4 (b)

End shearand end

reaction (a)24.0 (b)24.0 (b)24.0 (b)24.0 (b)24.0 (b)

24.0 (b)24.0 (b)24.0 (b)24.0 (b)24.0 (b)

24.0 (b)24.0 (b)24.0 (b)24.0 (b)25.6 (b)

27.0 (b)28.2 (b)29.3 (b)30.8 (b)31.2 (b)

32.0 (b)82.7 (b)83.4 (b)84.0 (b)34.6 (b)

35.1 (b)85.6 (b)36.0 (b)86.6 (b)37.2 (b)

87.7 (b)88.8 (b)88.7 (b)39.2 (b)89.6 (b)

40.0 (b)40.4 (b)40.7 (b)41.1 (b)41.4 (b)

Span Moment42 864.0 (b)44 8*0.7 (b)46 417.4 (b)48 444.1 (b)

470.9 (b)50

52 497.7 (b)54 524.5 (b)56 551.3 (b)58 578.1 (b)60 604.9 (b)

62 681.8 (b)64 658.6 (b)66 685.5 (b)

712.8 (b)739.2 (b)712.3

75 806.3 (b)80 878.7 (b)85 941.0 (b)90 1,008.3 (b)95 1,074.9 (b)

100 1,148.0 (b)110 1,277.7 (b)120 1,412.5 (b)130 1,547.8 (b)140 1,682.1 (b)

150 1,856.8160 2,076.0170 2.807.8180 2,551.5190 2,807.8

200 8,075.0220 8,646.5240 4,266.0260 4.933.5280 5,649.0

800 6,412.5

End shearand end

reaction (a)42.0 (b)42.5 (b)48.0 (b)48.5 (b)48.9 (b)

44.3 (b)44.7 (b)45.0 (b)45.8 (b)45.6 (b)

45.9 (b)46.1 (b)46.4 (b)46.6 (b)46.8 (b)

47.8 (b)47.7 (b)48.1 (b)48.4 (b)48.7 (b)

49.0 (b)49.4 (b)49.8 (b)50.758.1

65.557.960.362.765.1

•7J72.877.181.986.7

91.1

(a) Concentrated load is considered placed at the support. Loads used are thosestipulated for shear.

(b) Maximum value determined by Standard Truck Loading: (one H-S truck).Otherwise the Standard Lane Loading: governs.

APPENDIX "A" 241

Loading— H 20-S 16-44

Table of Maximum Moments, Shear* and Reactions —Simple Spans, One LaneSpans in feet; moments in thousands of foot-pounds; shears and reac

tions in thousands of pounds.These values are subject to specification reduction for loading of

multiple lanes.Impact not included.

Span

1...2...I...4...6...

6.7.8.(.

10.

Moment8.0 (b)

16.0 (b)24.0 (b)32.0 (b)40.0 (b)

48.0 (b)56.0 (b)64.0 (b)72.0 (b)80.0 (b)

11 88.0 (b)12 96.0 (b)1S 104.0 (b)14 112.0 (b)15 120.0 (b)

16 128.0 (b)17 .. 136.0 (b)18 144.0 (b)19 152.0 (b)20 160.0 (b)

21 168.0 (b)22 176.0 (b)23 184.0 (b)24 192.7 (b)25 207.4 (b)

26 222.2 (b)27 237.0 (b)28 , 252.0 (b)29 267.0 (b)30 282.1 (b)

81 297.3 (b)32 312.5 (b)38 827.8 (b)84 348.5 (b)85 S61.2 (b)

36 378.9 (b)87 896.6 (b)38 414.3 (b)39 432.1 (b)

.40 449.8 (b)

load i:

End shearand end

reaction (a)'32.0 (b)32.0 (b)32.0 (b)32.0 (b)32.0 (b)

32.0 (b)32.0 (b)32.0 (b)32.0 (b)32.0 (b)

32.0 (b)32.0 (b)32.0 (b)32.0 (b)34.1 (b)

36.0 (b)87.7 (b)39.1 (b)40.4 (b)41.6 (b)

42.7 (b)43.6 M>)44.5 (b)45.3 (b)46.1 (b)

46.8 (b)47.4 (b)48.0 (b)48.8 (b)49.6 (b)

50.3 (b)51.0 (b)51.6 (b)52.2 (b)52.8 (b)

53.3 (b)53.8 (b)54.3 (b)64.8 (b)55.2 (b)


52 668.6 (b)54 699.3 (b)56 785.1 (b)58 770.8 (b)60 806.5 (b)

62 842.4 (b)64 878.1 (b)66 914.0 (b)68 949.7 (b)70 985.6 (b)

75 1,075.1 (b)80 1,164.9 (b)85 1,254.7 (b)90 1,344.4 (b)95 1,433.2 (b)

100 1,524.0 (b)110 1,703.6 (b)120 1,883.3 (b)180 2.063.1 (b)140 2,242.8 (b)

150 2,475.1160 2,768.0170 3,077.1180 3,402.0190 8,743.1

200 4,100.0220 4,862.0240 5,688.0260 6,578.0280 7,582.0

300 8,550.0

End shearand end

reaction (a)£6.0 (b)56.7 (b)57.3 (b)58.0 (b)58.5 (b)

59.1 (b)59.6 (b)60.0 (b)60.4 (b)60.8 (b)

61.2 (b)61.5 (b)61.9 (b)62.1 (b)62.4 (b)

68.1 (b)68.6 (b)64.1 (b)64.5 (b)64.9 (b)

65.3 (b)65.9 (b)66.4 (b)67.670.S

74.077J80.488.686.8

90.0•6.4

102.8109.2115.6

122.0

considered placed at the support. Loads used are those( a ) Concentratedstipulated for ahear.

(b) Maximum value determined by Standard Truck Loading; (one H-S truck).Otherwise the Standard Lane Loading governs.

242 HIGHWAY BRIDGES

APPENDIX "B"

Formulas for Steel Columns*

The permissible average unit stress for steel columns shall be:

f, = v- P(A)

1 + (.25 + B Cosec 0A

P=load parallel to the axis of the member in lbs.a = gross cross-sectional area of column in sq. in.

f> = yield point stress in tension,= 33000 lbs. per sq. in. for carbon steel.

=45000 lbs. per sq. in. for silicon steel.= 55000 lbs. per sq. in. for nickel steel.= 50,000 lbs. per sq. in. for low-alloy steel, thickness % inch and under.=45,000 lbs. per sq. in. for low-alloy steel, thickness over % inch to

inch inclusive.=40,000 lbs. per sq. in. for low-alloy steel, thickness over 1 Yi inch to 2 inch

inclusive.

t) = factor of safety based on yield point,= 1.76 for carbon steel.= 1.80 for silicon steel.= 1.83 for nickel steel.= 1.82 for low-alloy steel, thickness % inch and under.= 1.80 for low-alloy steel, thickness % inch to 114 inch inclusive.= 1.78 for low-alloy steel, thickness 1H inch to 2 inch inclusive.

c= distance from neutral axis to the extreme fiber in compression.r= radius of gyration in the plane of bending

®~\ ^lt~radians

L = 75% of the total length of a column having riveted end connections.= 87.5% of the total length of a column having pinned end connections.

E = modulus of elasticity of steel

=29,000,000 lbs. per sq. in.

B =-^a2-2a cos 0 + 1

a = — : When eB and es lie on the same side of the column axis, o is positive;68 when on opposite sides, o is negative; i.e.

When +es = +eg, a = +1When es=0, cc=0

When +es = —eg, a = — 1

eg = eccentricity of applied load at the end of column having the greater com

puted moment, in inches.

es= eccentricity at opposite end.* Refer also to the column formulas given in articles 3.4.2, 3.4.7 and 3.4.8.

** When the radius of gyration perpendicular to the plane of bending is lessthan "r", the column shall be investigated for the case of a long column concen

trically loaded, having a greater value of — - •

APPENDIX "B 243

L / -1\ rE^14- 25 4- e-^\For values of - equal to or less than I cos «j V r2 /I— fy —

the permissible fs shall be determined from the formula:

A

1+.25

When the values of end moments are not computed but considered negli

gible in amount, a shall be assumed equal to +1.

a shall be assumed equal to +1 for a member subject to bending stresses

induced by the components of externally applied loads acting perpendicular to

its axis. For this case the general formula becomes:

„ (0,= 5 — * -1+ [ .25 + (eb+d)£] Sec^0 ^.f&j-h^'

d— deflection due to the transverse components of externally applied loads,

in inches. sI=moment of inertia of section about an axis perpendicular to the plane of J

bending, in (inches)4. 4M= moment due to the transverse components of externally applied loads,

in inch pounds.

Note: The value of 0.25 in the above formulas provides for inherent crookedness and unknown eccentricity.

Permissible unit stresses, in accordance with the formulas A and B givenabove, may be obtained from following graphs. Graphs are provided forcarbon and silicon steels; pinned and riveted end conditions, and for valuesof a= +1, 0, and —1. The graphs for silicon steel are applicable also to low-alloysteel, thickness over % inch to 1 14 inch inclusive.

Straight-line interpolation between a = +1 and 0, and between a = 0 and —1may be used for intermediate values of eccentricity ratios.

When egc/r2=0, the top curve for a = +l shall be used. The curves foregc/r2 =0 in the graphs for a =0 and a = — 1 are to be used for interpolating valuesof fs between egc/r2=0 and egc/r2 = .l.

244 HIGHWAY BRIDGES

0*ZOZZ003OBI0910»lOZI0010909Ofr020

0«OZZ002081091001OZI00109090»OZ0

9fZ saoamaavmhoih

248 HIGHWAY BRIDGES

APPENDIX CTRUCK TRAIN AND EQUIVALENT LOADINGS- 1935 SPECIFICATIONS

AMERICAN ASSOCIATION OF STATE HIGHWAY OFFICIALS

,15 TON TRUCK

o oo oo o■0 f\J

,20 TON TR

5 o ot 14' m 30'

.15 TON TRUCK,

3 0' . I . 14' 14' 30' 30'

H-20-35 LOADING

ill^TON TRUCK, ,15TON TRUCK,

TEL.ill* TON TRUCK, ,llaT0N TRUCK ,

9 9 n (). . I4'

. 30'^

l4'.. .

30 30' 14' 30' 30'

H-15-35 LOADINGooo

,7jT0N TRUCK.

12,10 TON TRUCK

o 0,7jf TON TRUCK, ,7; TON TRUCK,

D_ q O30'14' 30' 30'

H-IO-35 LOADINGTRUCK TRAIN LOADING

H-20-35 LOADING

-CONCENTRATED L0Ad{' ™" "°M

[ 19,500 FOR SHE)ENT

:ar

^.UNIFORM LOAD 480-LBS.PER LINEAR FOOT OF LANE

H-15-35 LOADING

l^-CONCENTRATED LOAD13/

,000 FOR MOMENT

,000 FOR SHEAR

^UNIFORM LOAD 320-LBS. PER LINEAR FOOT OF LANE

H-IO-35 LOADING

EQUIVALENT LOADINGLANE WIDTH 9 FEET

INDEX

Article PageAbutment :

Design, general 3. 5. 3 163Distribution of earth pressure 3. 5. 2 161Drainage 3. 5. 3d 164General 3. 4. 3a 163Pile bents 3. 8. 5f 200Reinforcement for temperature 3. 5. 3b 164Wing walls 3. 5. 3c 164

(See also Foundations and Substructures.)Acceptance :

Pinal payment 1. 9. 7 24No waiver of legal rights 1. 7.12 18

Aggregate:Bituminous carpet 2.24.22 117Coarse, for concrete 4. 4. 1 212Fine, for concrete 4. 3. 1 212Rubble or cyclopean 4. 4. 2 212Sand for mortar 4. 3. 2 212

Anchor Bolts and Anchorages 2.10.51, 3.5.2b, 3.6.43, 3. 6.53 .78, 161, 176, 177Angle of Repose (various materials) 3. 4.16 155Annulment of Contract 1. 8. 8 21

Appendixes :

Charts for, Appendix B 242, 244Permissible stresses, reinforced concrete tied

columns, Appendix D 249Tables of moments, shear and reactions for H 15,

H 20, H 15-S 12, H 20-S 16 loadings. App'x A 238, 239, 240, 241Truck train and equivalent loadings. App x C 248

(1935 specifications — for reference use.)Arbitration, Board of 1. 5.12 15Arches :

Ashlar masonry 2. 6.15 64Concrete —

Class of concrete 2. 4. 4 38Drainage of fill 3. 7.1 1f 198Expansion joints 3. 7.11c 198Placing concrete 2. 4. 9 44Reinforcement 3. 7. lid 198Shape of ring 3. 7.11a 197Spandrel walls 3. 7.11b 198Surface finish 2. 4.23 53Waterproofing 3. 7. lie 198

General—Centering (see Centering and Falsework).Drainage 3. 7.11f 198Fill 2. 1. 9 27Waterproofing 3. 7. lie 198

Rubble masonry 2. 7. 8 66Sectional plate (see Sectional Plate Arches).

Ashlar Masonry :

Arches (see Arches) —Copings 2. 6.14 64Description 2. 6. 1 61

Dowels and cramps 2. 6.13 64Dressing stone 2. 6. 5 61

Laying—Cores and backing 2.6.8, 2. 6.15 62,64Headers and stretchers 2.6.6, 2 . 6 . 7 62

251

ArticleLaying stone—

Concrete cores and backing 2. 6.10dFace stone 2. 6.10bGeneral 2. 6.10aStone backing and cores 2. 6.10c

Leveling courses 2. 6.11Material 2.6.2, 4.20. 1

Mortar and mixing 2.6.2, 2. 6. 9Payment conditions 2 . 6 . 17Pointing 2. 6.16Resetting 2. 6.12Size of stone 2. 6. 3Surface finish 2. 6. 4

Asphalt Mat (see Bridge Floors.)Asphalt Paving Blocks :

Absorption test 4.23. 6cBridge wearing surface (see Bridge Floors).Composition 4.23. 6bGeneral 4.23. 1

Manufacture 4.23. 5

Materials —Asphaltic cement 4.23. 2

Inorganic dust 4.23. 4Mineral aggregate 4.23. 3

Physical characteristics 4 . 23 . 6

Asphalt Plank 4.24. 1

B

Backfill (see Excavation and Fill).Bar Reinforcement 2.5.1,2.5.6, 4. 5. 1

Barricades and Warning Signs 1.4.5, 1. 7 . 7

Bid—right to reject 1 . 3 . 1

BidderCompetency !. 2.11Definition 1. 1.1Disqualification 1. 2.10Instructions to 1 . 1 . 1

Bituminous Carpet:Asphalt 4.22. 4Tar 4.22. 3

(See also Bridge Floors.)Bituminous Filler

Oil asphalt 4.22. 1

Premoulded 4.22. 2

Blast Protection 3. 1.14Board, Arbitration 1. 5.12Board, definition 1. 1. 1

Bracing:Cofferdams 4. I. o

Framed and pile bents 2 . 20 . 12, 2 . 20 . 13Steel structures 3 . 6 . 65, 3 . 6.72Wooden truss spans . 3 . 8 . 6

Brick for Masonry 4.21. 1

(See also Brick Masonry.)Brick for Pavement :

Bridge wearing surface (see Bridge Floors).Material 4.21. 1

252

Article PageBrick Masonry:

Construction 2. 9. 3 68Copings, bridge seats, backwalls 2 . 9 . 4 69Description 2. 9. 1 68Material 2.9.2,4.21.1, 4.21. 2 68,227Mortar 2. 9. 2 68Payment conditions 2 . 9 . 5 69Railings (see Railings and Parapets).

Bridge:Clearances, roadway 3. 1. 8 122Highway loadings (see Loads) 3. 2. 5 129

Bridge Floors:Asphalt plank 4.24. 1 232

Concrete —Class of 2. 4. 4 38Curing 2. 4.21 52Drainage 3. 1.11 124Expansion joints 2.4.22, 3. 7. 5 52,192Placing concrete 2. 4. 9a, b, c, d 44—47Placing reinforcement 2. 5. 7 59Surface finish 2.4.23, 2. 4.31 53,56

Laminated or strip, general 2.20.18 103Nonskid 3. 1.13 124

Plank-Details 2.20.17 103Design 3. 8. 7d 202Drainage 3. 8. 7g 202Fire stops 3. 8. 8 202General 2.20.17 103Materials 2.20.17 103Retaining pieces 3. 8. 7e 202Wheel guards 3. 8. 7f 202

Steel grid—Computed weight 2.10.67g 82

Construction —Arrangement of sections 2.12. 3 83Concrete filler 2.12. 9 84Connection to supports 2.12. 6 83Field assembly 2.12. 5 83General 2.12. 1 83Materials 2.12. 2 83Painting 2.12.10 84Provision for camber 2.12. 4 83Repairing damaged galvanized coatings 2 . 12 . 8 84Welding 2.12. 7 84

Design, distribution, moments 3. 3. 5 143Materials —

Concrete filler 4.15. 3 218Protective treatment 4.15. 2 217Steel 4.15. 1 217

Measurement and payment 2.12.11 85Wearing surfaces—

Allowance for 3. 2. 2 127Asphalt block —

General requirement 2.24.15 116Laying 2.24.19 116Materials 2.24.16 116

Measurement and payment 2.24.21 117Mortar bed 2.24.18 116

Opening to traffic 2.24.20 117Preparation to subfloor 2.24.17 116

253

Article Page

Bituminous carpet—Aggregate 2.24.23 117Asphalt mat surface, construction —

Mixed method —Prime coat 2.24.26a 119Seal coat 2.24.26c 119Second coat 2.24.26b 119

Penetration method —Prime coat 2.24.27a 120Second coat 2.24.27b 120

Materials 2.24.23,4.22.3, 4.22. 4 ....117,228,228Measurement and payment 2.24.29 120Opening to traffic 2.24.28 120Preparation of subfloor —

Concrete subfloor 2.24.24b 118Wood subfloor 2.24.24a 117

Tar mat surface —Construction 2.24.25 118Prime coat 2.24.25a 118Seal coat 2.24.25b 118Second coat 2.24.25c 118

Brick-Asphalt filler —

Application 2.24.11 115Bedding course, placing 2.24. 7 114General requirements 2.24. 3 113Laying 2.24. 8 114Materials 2.24.4, 4.21. 1 113,227Measurement and payment 2.24.14 115Opening to traffic 2.24.13 115Preparation of subfloor 2.24. 5 113Rolling the brick 2.24. 9 115Sand— cement bed 2.24. 6 114Surface dressing 2.24.12 115Testing the surface 2.24.10 115

Concrete —Description— 2.24. 1 113Measurement and payment 2.24. 2 113

Broken Stone for Concrete 4. 4. 2 212

Bronze Bearing and Expansion Plates :

Bronze sliding expansion bearings 3. 6.48 177Bronze plates 2.11. 3 82Copper-alloy plates 2.11. 4 82General 2.11. 1 82

Material 2.11.2, 4.12. 1 82,216Measurement and payment 2.11. 6 82Placing 2.11. 5 82Unit stresses 3. 4. 9 148

Buoyancy 3. 2.17 137

Buttresses and Counterforts 3. 5. 4d 165

Camber :

Diagram required 2.10.13 71

Steel girders 3. 6.85 183Steel trusses 3. 6.90 184Timber trusses 3. 8. 6f 201

Cantilever Slabs 3. 3. 2f 141

254

Article PageCastings :

Gray iron 4.10. 1 215Cleaning 4.10. 3 216Workmanship and finish 4.10. 2 216Malleable 4.11. 1 216Steel (see Steel, Castings).Unit stresses (see Stresses, Unit).

Cement:Sampling and testing 4. 1. 2 211Types I, II, III, IV and V 4. 1. 1 211

Centering and Falsework 2.4.17, 2.10.49 50, 78Removal of falsework, forms and housing 2. 4.19 51

Channel of Stream:Erosion 2. 1. 2 25Openings 3. 1. 3 121Preservation 2. 1. 2 25

Claims :

Contractor's responsibility, damages 1.7.7, 1. 7.10 17, 18Disputed 1. 5.11 14

Cleaning Up 1. 4. 8 12Clearance Diagrams Figs. 1,2 121, 122, 123, 125Cofferdams and Cribs:

Construction 2. 1. 5 26Construction plans 2 . 1 . 5c 26General 2. 1. 5a 26Preservation of channel 2.1.2 25Protection of concrete 2. 1. 5b 26Pumping 2. 1. 6 26Removal 2. 1. 5d 26(See also Concrete Cribbing; Timber Cribbing.)

Cold Weather:Concrete construction 2. 4.20 52Painting 2.14. 5 87

Commission :

Appointment of arbitration board 1. 5.12 15Definition 1. 1. 1 6

Personal liability 1. 7.11 18Composite Beams :

Deflection 3. 9. 5 204Effective flange width 3. 9. 2 203General assumptions 3. 9. 1 203Shear 3. 9. 4 203Shear devices 3. 9. 6 204Steel-concrete 3. 9. 1 203Stresses 3. 9. 3 203Timber-concrete 3. 9. 1 203

Concrete :

Bearing piles (see Pile Concrete).Bonding 2. 4.13b 49Cement for 4. 1. 1 211Classes of 2. 4. 4 38Classification and proportioning 2. 4. 5 38-41Coarse aggregate 4. 4. 1 212Cold weather construction.. . .2. 3. 13c, 2.3. 13g, 2.4.20 33,34,52Consistency 2. 4. 6 41Construction joints —

Bonding 2. 4.13b 49General 2. 4.13a 49Curing 2.3.13g, 2. 4.21 34,52

Cyclopean or rubble 2 . 4.14 49Depositing under water 2. 4.12 48Discontinuance of placing 2. 4. 9a 44-46

255

Arrte

Handling ;

Arche

expansion joints in 2. 4.22Expansion and fixed joints and bearings—

Bearing devices 2. 4.22eFilled joints 2. 4.22bOpen joints 2. 4.22aSteel joints 2. 4.22cWater stops - 2. 4.22d

Exposed to alkali soil or watpr 2. 4.16Exposed to sea water . - 2. 4.15Fine aggregate *- 3- 1

Finishing surfaces —Class 1, Ordinary 2. 4.24Class 2, Rubbed 2. 4.25Class 3, Tooled 2. 4.26Class 4, Sand blasted 2. 4.27Class 5, Wire brushed 2. 4.28Class 6, Floated—

Final finishing 2. 4.29fFloating 2. 4.29bLongitudinal floating 2. 4.29cStraightedging 2. 4.29eStriking off 2. 4.29aTransverse floating 2. 4.29d

General 2. 4.23Forms 2.4.9,2.4.18,2. 4.19

■and placing —hea.. ..... 2. 4. 9d

Culverts 2. 4. 9bGirders, slabs and columns 2. 4. 9cGeneral 2. 4. 9a

Measurement and payment 2. 4.32Measuring materials 2. 4. 7

Mixing—Delivery 2. 4. 8hGeneral. 2. 4. 8aHand mixing 2. 4. 8gMixing at site 2. 4. 8bPartial mixing at central plant 2. 4. 8dPlant mix 2. 4. 8eRetempering 2. 4. 8iTime of hauling and placing mixed concrete . 2 . 4 . 8fTruck mixing 2. 4. 8c

Pneumatic placing 2. 4.10Pneumatically applied mortar —

Bond 2. 4. Securing 2. 4.31kForms 2. 4.31hGeneral 2. 4.31aJoints 2. 4.31iMixing 2. 4.31dNozzle position 2. 4.31fNozzle velocity . . . 2. 4.31eProportions 2. 4.31bRebound sand 2. 4.31gWater content 2. 4.31c

Pumping 2. 4.11Re tempering 2. 4. 8iSheet piles 2.2.1,2. 2. 3

Storage of materials 2. 4. 2Surface finish 2. 4.23

256

Article

Sidewalk 2. 4.30(See also Finishing Surfaces.)

Water for 4. 2. 1Weather protection 2.3.13,2. 4.20Weighing equipment 2. 4. 7

Concrete Arches (see Arches — Concrete).Concrete Cribbing:

Construction 2.16. 2

General 2.16. 1

Measurement and payment 2.16. 3Concrete Culverts —Monolithic :

Class of concrete 2. 4. 4Footings 3 . 5 . 2Inverts, aprons, curtain walls 3. 5. 2

Placing concrete 2 . 4 . 9bSurface finish 2. 4.23

Concrete Railings (see Railings and Parapets).Concrete Reinforcement :

Anchorage 3. 7. 9dBar mat 2. 5. 6

Cleaning 2. 5. 7Design Sec. 7

Fabrication 2. 5. 4

Formulas 3. 7. 3Lapping 2. 5. 9Material 2.5.1,4. 5. 1

Mesh 2. 5. 5Measurement and payment 2.5.11,2. 5.12Placing and fastening 2. 5. 7Protection of , 2 . 5 . 3Splices 2. 5. 8

Stirrups 3. 7. 9

Structural shapes 4. 5. 4

Substitutions 2. 5.10Substructure and retaining wall. .. .3.5.2, 3.5.3,3. 5. 4

(See also Reinforcement, Concrete.)Concrete Slabs and Girders :

(See also Slabs.)Camber 2. 4.17Class of concrete 2. 4. 4Drainage 3. 1.11Placing concrete 2 . 4 . 9cSurface finish 2. 4.23Waterproofing Sec. 17

Concrete Structures :

Arches (see Arches —Concrete).Cold weather construction 2. 4.20Cribbing (see Concrete Cribbing).Culverts (see Concrete Culverts).Design —

Allowable stresses —Bearing on bridge seats 3. 4.11fBond on piles (in seals) 3. 4. lieColumns 3. 4.11gFlexure 3. 4.11cGeneral 3. 4.11bShear 3. 4. lidStandard notations and assumptions. . . 3. 4.11a

Arches —Drainage of fill 3. 7.11fExpansion joints 3. 7.11c

257

Article Page

Reinforcement 3. 7. lid 198Shape of ring 3. 7.11a 197Spandrel walls 3. 7.11b 198Waterproofing 3. 7. lie 198

Beams (Composite) 3. 9. 1 203Columns —

Columns with lateral ties 3. 7.10b 196Flexure and direct stress 3. 7.10d 196General 3. 7.10a 195Spiral columns 3. 7.10c 196Stresses, Appendix D 3. 4.11g 150

Diaphragms 3. 7. 6d 193Expansion joints 2.4.22, 3 . 7 . 5 52,192Formulas —

Columns with lateral ties 3. 7. 3d 192Flexure of rectangular reinforced con

crete beams and slabs 3. 7. 3a 188Flexure of reinforced concrete T-beams 3. 7. 3b 189Shear, bond and web reinforcement 3. 7. 3c 190Spiral columns 3. 7. 3e 192

General assumptions 3.4.11b, 3. 7. 1 149,186Moments in floor slabs 3. 3. 2 139Reinforcement —

Anchorage 3. 7. 7d 193Compression in beams 3. 7. 8 194Covering 3. 7.76b 193Extension 3. 7. 7e 193Maximum size 3 . 7 . 7f 194Spacing 3. 7. 7a 193Splicing 3. 7. 7c 193

Reinforcement —web —Anchorage 3. 7. 9d 195Bent-up bars 3. 7. 9b 195Vertical stirrups 3. 7. 9c 195

Span lengths 3.3.2i, 3. 7. 4 142,192Standard notations 3.4.11a, 3. 7. 2 148,187T-Beams—

Diaphragms 3. 7. 6d 193Effective flange width 3. 7. 6a 192Isolated beams 3. 7. 6c 193Shear 3. 7. 6b 192

Unit stresses (see Stresses).Viaduct bents and towers 3. 7.12 198

Concrete Substructures :

Class of concrete 2 . 4 . 4 38Construction joints 2. 4.13 49Drainage 3.2.18, 3. 5. 4g 137,165Foundation protection 3. 5. 2 161

Placing concrete 2 . 4 . 9 44Surface finish 2. 4.23 53

Concrete Viaducts :

Bents and towers 3. 7.12 198Class of concrete 2 . 4 . 4 38Column forms 2. 4.18 50

Placing concrete 2. 4. 9c 46Concrete Wearing Surfaces (see Bridge Floors).Connectors 2.20.2,3.4.14,3.8.4, 4.27. 1 .99,152,199,236Construction :

Acceptance no waiver, legal rights 1. 7.12 18

Defective and unauthorized 1. 5. 9 14Final work at site 1. 4. 8 12

258

Article

Limitation of (operations 1. 8. 3Non-completion, contract time 1. 8. 2

Notice of beginning of work 2 . 10 . 39Prosecution of 1 . 8 . 2Quantities, measurement 1. 9. 1

Stakes 1. 5. 6

Superintendence 1.5.5, 1. 8. 4

Temporary suspension 1. 8. 5

Workmen and equipment 1. 8. 4

Contract :

Annulment 1. 8. 8

Approval 1 . 3. 6

Arbitration board 1. 5.12Award 1. 3. 2

Bond, definition 1. 1 . 1

Bond, requirements 1. 3. 4Compensation for delays 1. 8.10Definition 1 . 1 . 1

Disputed claims 1. 5.11Execution 1. 3. 5

Extension, contract time 1. 8. 6

Extra work 1. 4. 4Failure to complete on time 1. 8. 7

Failure to execute 1. 3. 7

Final acceptance 1.4.8, 1. 9. 7

Final payment 1 . 9. 7Included documents 1. 1 . 1

Omitted terms 1. 9. 5

Prosecution and progress 1. 8. 2

Quantity changes 1.4.3, 1. 9. 3

Quantity measurements 1. 9. 1

Special work 1- 4. 2

Subletting or assignment '. . . 1 . 8 . 1

Termination 1. 8. 9

Time extension 1 . 8. 6Contract Bond, requirement of 1 . 3 . 4

Contractor :

Claim for extras 1 . 5.11Compensation for delays 1. 8.10Cooperation of 1.5.5,1.8.2, 2.10.40Definition 1 . 1 . 1

May use certain materials it 4. 7

Notice of beginning of work 2 . 10 . 38Responsibility for construction stakes 1. 5. 6

Responsibility for damages 1.4.5, 1.7.7, 1. 7. 9

Responsibility for temporary constructions 1. 4. 5

Responsibility for work 1.7.7, 1. 7.10Sub-contractor, definitionTermination of responsibility 1.7.7, 1. 8. 9

Working drawings 1. 5. 2

Copper Alloy Bearing and Expansion Plates :

Materials 4.12. 2

Measurement and payment 2.11. 6

Placing 2.11. 5

Unit stresses 3. 4. 6

Counterforts and Buttresses 3 . 5 . 4dCounty, definition 1. 1. 1

Cribs (see Cofferdams and Cribs; also TimberCribbing).

Crossings, temporary 1. 4. 5

259

Article PageCulverts :

Concrete (see Concrete Culverts, Monolithic).Foundations 3. 5. 2 161

Length 3. 1. 6 122Loads on :

Weight of earth 128Weight on rigid culverts 128

Size of waterway 3. 1. 5 122Curbs, Safety 3.2.11, 3. 1. 9 134,122Curbs and Wheel Guards 2.20.19,3.1.9, 3. 8. 7f ....104,122,202Current, force of 3 . 2 . 6 137

D

Damage, responsibility 1.4.5,1.7.7, 1. 7. 9 11,17,18Dampproofing :

Application 2.18. 4 97General 2.18. 1 97Materials 2.18. 2 97Measurement and payment 2.18. 5 100Preparation of surface 2.18. 3 97

Dead Load (see Loads— Dead Load).Defective Workmanship 1.5.7, 1. 5. 9 13,14Definition of Terms 1. 1. 1 6-8Deflection, steel beams and girders 3. 6.10 168Delivery of Materials 2.10.47 78Department, definition 1. 1. 1 6Depressed Roadways —

Clearance between walls 3. 1.17 126Curbs, minimum width 3. 1.17 126Width between curbs 3. 1.17 126

Design, General Features:Analysis (Rational Acceptable).Blast protection 3. 1.14 124Channel openings 3. 1. 3 121Classes of loadings 3. 2. 5 129Clearances 3. 1. 8 122Culvert, length 3. 1. 6 122Culvert, size 3. 1. 5 122Curbs and safety curbs 3. 1. 9 122Depressed roadways 3. 1.17 126Drainage, roadway .. .' 3. 1.11 124Floor surfaces 3 . 1.13 124Loads (see Loads).Pier spacing and location 3. 1. 4 121Preservation of channel 2. 1.2 25Railings 3. 1.10 124Roadway and sidewalk widths 3. 1. 7 122Superelevation 3. 1.12 124Tunnels 3. 1.16 125Underpasses 3. 1.18 126Unit stresses (see Stresses).Utilities 3. 1.15 125Waterway area 3. 1. 1 121Waterway restricted 3. 1.2 121

Detours, construction and maintenance 1. 4. 5 11Disqualification of Bidders 1 . 2.10 9Distribution of Loads (see Loads).Drainage of Structures 2.6.15,2.7.8,3.1.11,3.2.18,3. 5. 4g ..64,66,124,137

3.7.11f, 3. 8. 7g ....165,198,202

260

ArticleDrawings :

Contractor's 1. 5 . 2

Deviation from 1. 5 . 3

Engineer's approval 1. 5 . 2

EEarth Pressure :

Angle of repose 3. 4.16Pressure 3. 2.18

Engineer :

Acceptance by 1 . 9 . 7

Access to work 1. 5. 8

Authority of 1.5.1, 1.8.2Definition 1. 1. 1

Measurement of quantities 1. 9. 1

Personal liability 1. 7.11Plans and working drawings 1. 5. 2

Precautions for public safety 1. 7. 7

Resident, definition 1. 1. 1

Stakes for construction uses 1. 5. 6

Equipment, adequacy of 1 . 8 . 4

Erosion Protection:Piles 3. 5. laRiprap 2.15.1, 2.15.11(See also Foundations and Substructures.)

Estimate :

Interpretation of 1 . 2 . 2

Quantities 1. 4. 3

Excavation and Fill :

Arches, spandrel filled 2. 1. 9

Backfill-Construction . • 2. 1. 8

Drainage 2.1.8, 3. 7. 1 IfMaterials 2 . 1 . 8

Cofferdams and cribs—Construction 2. 1. 5

Pumping 2. 1. 6

Removal 2. 1. 5

Sheet piles Sec. 2

Embankment —Approach 2 . 1.10Construction 2. 1.10Measurement and payment 2. 1.12

Excavation —Backfill 2. 1. 8

Classification 2 . 1.11Cofferdam and crib protection 2. 1. 5

Foundation, preparation 2. 1. 4

Inspection 2. 1. 7

Measurement and payment 2. 1.12(See also Foundations and Substructures.)

Existing Bridges, rating of :

General 3.12. 1

Inventory 3.12. 2

Operating 3.12. 3

(See also Rating of Existing Bridges.)Existing Structures 1 . 4.. 6, 2 . 10 . 58Expansion Joints:

Bituminous 4.22. 2Bridge floor 2.4.22, 3. 6.64Bridge railing 2.13.11Concrete structures 2.4.22, 3. 7. 5

261

Article

Extra Work 1. 4. 4Eyebars:

Annealing and annealing record 2 . 10 . 32, 4 . 6.13Design 3.6.93,3.6.94, 3. 8. 6

Fabrication 2.10.31Full size test 4. 6. 9Payment for full size tests 2.10.59, 4. 6.14Physical requirements 3.8.6,4.6.8, 4. 6.12Test bars and testing 4. 6.10

FFabrication of Steel Structures :

(Riveted unless otherwise specified) 2 . 10 . 1

Falsework and Centering (see Centering andFalsework).

Federal Participation 1. 7 . 4Fill (see Excavation and Fill).Final Inspection 1. 5.10Fire Stops 3. 8. 8Flame Cleaning 2.14.10dFlame Cutting 2.10.22Floors (see Bridge Floors).Footings (see Foundations and Substructures).Forgings, Steel (see Steel Forgings).Forms for Concrete (see Concrete).Foundations :

Excavation 2. 1. 1Falsework support 2. 4.17Piles 2.3.3,3.4.17, 3. 5. 1

Timber cribbing Sec. 22Foundations and Substructures ;

Abutments (see Abutments).Anchor bolts 2.10.51Anchorage 3. 5. 2b

- Bearing power of soils 3. 4.15Bearing plates 2 . 10 . 51

Cofferdams 2. 1. 5

Concrete and concrete placing —Classes of concrete 2. 4. 4Construction joints 2. 4.13Placing concrete 2. 4. 9Surf ace finishes 2. 4.23

Depth below soil surface 2.1.3, 3. 5. 2aDistribution of pressure 3. 5. 2cDrainage 2.1.8, 3. 5. 3dEarth pressure —

Angles of repose 3. 4.16Pressure 3. 2.18

Excavation 2. 1. 4Footings —

Anchorage 3. 5. 2bDepth 3. 5. 2aDistribution of pressure 3. 5. 2 cInternal stresses in spread footings 3 . 5 . 2ePiles Sec. 3, 3. 5. 1

Preparation of foundation 2. 1. 4Protection against erosion 3. 5. 2

Reinforcement 3. 5. 2fSpread footings 3 . 5 . 2dTransfer of stress from verical reinforcement . . 3 . 5 . 2g

Ice breakers 3. 5. 5

262

Article

Ice pressure 3. 2.16Inspection and approval 2 . 1. 7

Piers (see Piers).Tubular steel piers (see Tubular Steel Piers).

General Provisions, definition of terms 1. 1. 1

Girders and Slabs (see Concrete Slabs and Girdersand Slabs).

Girders— Steel (see Steel Structures; Plate Girders;Viaducts).

Gravel, (or concrete 4. 4 . 1

H

Hammers, pile-driving 2. 3. 4

Highway Lave Loads (see Loads —Live Load).Horizontal Shear in Beams 3. 4.14

I

Ice Breakers 3. 5 . 5

Impact (see Loads — Impact).Inspection :

Engineers and inspectors, access for 1.5.8, 2 . 10 . 40Final 1. 9. 7

Inspector :

Access to work 1.5.8, 2.10.40Authority and duties 1.5.7, 2.10.41Definition 1. 1 . 1

Iron :

Gray iron castings 4.10. 1

Wrought 3.4.4, 4. 7. 1

JJoints :

Abutting, metal 2.10.24, 3. 8. 6

Construction joints, concrete (see Concrete).Expansion (see Expansion Joints).Fillers-

Oil asphalt 4.22. 1

Premoulded 4.22. 2

L

Laboratory, definition 1. 1. 1

Lacing Bars, design 3. 6.36Lane (see Loads).Lateral Forces (see Loads).Laws (see Legal Relations).Legal Relations :

Federal participation 1. 7. 4Legal rights of state 1. 7.12Observance of laws 1. 7. 1

Patented processes 1. 7. 3

Permits and licenses 1. 7. 2

Live Loads (see Loads).Loads :

Application 3. 2. 8

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Article

Loads :

Application —H-lane loadings —continuous spans 3. 2. 8cLoading for maximum stress 3. 2. 8dNumber and position, traffic lane units ... 3. 2. 8bTraffic lane units 3. 2. 8a

Buoyancy 3. 2.17Current, floating ice and drift 3. 2.16Culverts :

Weight of earth assumed 3 . 2 . 2aEarth pressure by formula 3 . 2 . 2b

Dead load—weights 3. 2. 2

Distribution of wheel loads—Design of concrete slabs—

Bending moment 3 . 3 . 2aCantilever slabs 3 . 3 . 3fDistribution reinforcement 3 . 3 . 2cEdge beams (longitudinal) 3. 3. 2bEdge distance 3. 3. 2hShear 3. 3. 2dSlabs supported on four sides 3 . 3 . 2gSpan lengths 3 . 3 . 2iUnsupported edges (transverse) 3 . 3 . 2e

Steel grid floor—Floor filled with concrete 3 . 3 . 5bGeneral 3. 3. 5aOpen floors 3 . 3 . 5c

Stringers and floor beams —Bending moment in floor beams 3. 3. lcBending moment in stringers 3 . 3 . lbPosition of loads for shear 3. 3. la

Through earth fills 3. 3. 3

Timber flooring —Continuous flooring 3 . 3 . 4cLongitudinal 3 . 3 . 4bTransverse 3 . 3 . 4a

Earth Pressure 3. 2.18Electric railway 3. 2.10General 3. 2. 1

Impact 3 . 2 . 12Live, highway —

Application 3. 2. 8

Classes 3. 2. 5dDesignation 3.2.3, 3. 2. 5e

General 3. 2. 5aH loadings 3. 2. 5bH-S Loadings 3. 2. 5cLane Loadings 3.2.6, 3. 2. 7

Minimum 3. 2. 5fStandard trucks 3. 2. 7

Traffic lanes 3 . 2 . 6

Live, highway (1935 specifications), App'x CLongitudinal forces 3. 2.13Overload provision 3. 2. 4

Piles-Bearing value 2. 3. 6

Design 3.4.17, 3. 5. 1

Reduction in intensity 3. 2. 9

Sidewalk and safety curb 3. 2.11Tables of moments, shears, etc., Appendix AThermal 3. 2.15

264

Article Page

Wearing surface, allowance for 3. 2. 2 127Wind 3. 2.14 136

Longitudinal Forces (see Loads).Longitudinal Stiff eners (Plate Girders) 3. 6. 8 183Low-Alloy Steel 3.4.7, 4. 6. 4 147,213Lumber (see Timber, Lumber and Piles).

MMalleable Castings :

Cleaning 4.11. 3 216Material 4.11. 1 216Workmanship and finish 4.11. 2 216

Masonry:Ashlar (see Ashlar Masonry).Brick (see Brick Masonry).Railings (see Railings and Parapets).Rubble (see Rubble Masonry).

Masonry Arches (see Arches).Materials:

Aggregates, coarse 4. 4. 1 212Aggregates, fine 4. 3. 1 212Asphalt plank (premolded) 4.24. 1 232Bituminous Sec. 22 227Brick Sec. 21 227Bronze Sec. 12 216Cement Sec. 1 211Chromium alloy-steel castings 4. 9. 2 215Copperi alloy Sec. 12 216Defective 1. 6. 4 16Eyebars (see Structural Steel).Found on site 1. 4. 7 11Gray iron castings Sec. 10 215Malleable castings Sec. 11 216Paint-

Aluminum 4.16. la 218Black 4.16. lb 218First field coat 4.16. 3 219Second field coat 4.16. 4 219Shop coat 4.16. 2 219Timber structures 4.16. 1 218

Patented 1. 7. 3 17Preservative treatment for timber section Sec. 21 104Reinforcement Sec. 5 212Sectional plate arches Sec. 19 224Sectional plate pipe Sec. 19 224Sheet metal Sec. 18 224Source and quality of 1. 6. 1 15Steel castings (see Steel, castings).Steel forgings (see Steel, forgings).Steel grid Sec. 15 217Steel piles Sec. 13 216Steel sheet piles Sec. 14 217Stone for concrete Sec. 4 212Stone for masonry Sees. 6, 20 61, 226Storage 1.6.3,2.4.3,2.10.3, 2.20.3 ....16,37,69.99Structural and rivet steels (see Steels).Tests 1. 6. 2 15

Timber preservative oils 4.26. 1 235Water 4. 2. 1 211Waterproofing 4 . 22 . 5-4 . 22 . 1 1 229, 230Welding Sec. 17 223

265

Article

Wood preservatives Sec. 26Woods, structural Sec. 25Wrought iron Sec. 7

Mortar :

Ashlar masonry 2. 6. 2

Cement for 4. 1. 1

Pneumatically applied 2. 4.31Rubble masonry 2. 7 . 2

Sand for 4. 3. 2Water for. , 4. 2. 1

NName Plate Sec. 19 3. 6.54Nickel Steel (see Steel, structural).Notation, concrete design, Figs. 10, 11, 12 3. 7. 2Nuts:

Pilot and driving 2 . 10 . 37, 2 . 10 . 55Pin 3. 6.42Sleeve 3. 6.45

OOfficials, personal liability 1. 7.11Oil Asphalt Filler 4.22. 1

Oil, wood preservatives 4.26. 1

Overload Provision 3. 2. 4

PPaints and Painting:

Materials —Metals 4.16.2,4.16.3, 4.16. 4Timber structures 4.16. 1

Metal structures —Application —

Brushing 2.14. 6bGeneral 2.14. 6aInaccessible surfaces 2 . 14 . 6d

Spraying 2.14. 6cCleaning surfaces —

General 2.14.10aMethod A 2.14.10bMethod B 2.14.10cMethod C 2.14.10dSurfaces inaccessible after assembly. . . 2.14.10e

Coats and colors 2 . 14 . 3

Contact and inaccessible surfaces 2 . 14 . lOeErection marks 2.14.11Field 2.14.12,4.16.3, 4.16. 4Galvanized surfaces 2.14. 9General 2.14. 1

Machine finished surfaces 2 . 14 . 11Mixing 2.14. 4

Removal 2.14. 7

Shop 2.14.11, 4.16. 2Thinning 2.14. 8Weather conditions 2 . 14 . 5

Welded surfaces 2.14.11Patented Processes and Materials 1. 7. 3Payment :

Ashlar masonry 2. 6.17Asphalt block wearing surfaces 2 . 24 . 21Bituminous mat surfaces 2 . 24 . 29

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Article

Brick masonry 2. 9. 5

Brick wearing surface 2 . 24 . 14Concrete 2. 4.32Concrete cribbing 2.16. 3

Concrete wearing surface 2.24. 2

Embankment 2. 1.12Excavation and fill 2. 1.12Extra work 1. 9. 4

Final J. 9. \Force account work 1. 9. 4

Full size tests, eyebars 2 . 10 . 59

Full size tests, steel members 4. 6.14Omitted items 1. 9. 5

Partial 1. \. 6Pile, loading test 2. 3.20Piles —wooden; concrete; steel 2. 3.18Quantity changes 1.4.3, 1. 9. 3

Quantity measurements 1. 9. 1

Railings and parapets 2.13.14Reinforcing steel 2. 5.12Riprap 2. 5.11Rubble masonry 2. 8. 8

Scope of 1. *. 2

Sheet piles 2. 2. 5

Steel grid 2.12.11Steel structures 2 . 10 . 60Timber cribbing 2 . 22 . 6

Timber structures 2 . 20 . 23Waterproofing 2.17. 9

Permits and Licenses 1 . 7 . 2

Phosphor Bronze (see Bronze).Piers:

Design—13. 1. 4

General 5. 5aPier nose 3. 5. 5b

Distribution of earth pressure 3. 5. 2 c

Tubular (see Tubular Steel Piers).Piles: . o o , ,

Additional equipment ^ . o. 4aBattered 3. 5. leBearing Values 3 . 4.17

Capacity as structural member 3. 4.17bCapacity to transfer load to ground 3. 4.17cCapacity of ground to support piles 3 . 4 . 17dGeneral 3. 4.17aGroup Loading 3. 4.17gSub-Surface investigations uplift 3. 4.17dUplift 3. 4.17f

Design loads 2.3.2, 3. 5. 1

General 3. 5. 1

Group Loading 3. 4.17Leads 2. 3. 4eLoading test 2.3.6, 2. 3.20Methods of driving, general 2 . 3 . 4aOrder lists 2. 3. 8

Payment —Additional requirements 2. 3.18eCutoff 2. 3.18bDriving 2. 3.18cFalsework and defective 2. 3.18dFurnishing 2 . 3 . 1 8b,

267

Article Page

Method A 2. 3.18b 35

Method B 2. 3.18c 36

Payment 2. 3.18b, c 36

Projection into footings 3. 5. lc 159

Protection against scour 3. 5. 1 158

Spacing 3. 5. 1 158

Steel 2. 3. 3 29

Steel sheet 2. 2. 1 28

Steel shell (concrete filled) 2.3.3 29

Sub-surface Investigations 3. 4.17 155

Tubular Steel Piers 3. 5. 6 165

Uplift 3. 4.17 155

Piles, concreteAccuracy of driving 2. 3. 4h 31

Bearing values 2. 3. 6 31

Caps 2. 3. 3b 29

Cast in place —Class of concrete 2. 3.15c 34

Extension or "build-ups" 2. 3.16 35

General 2. 3.15a 34

Metal shells 2. 3.15b 34

Painting 2. 3.17 35

Payment conditions 2. 3.18 '. 35

Placing concrete 2. 3.15e 34

Reinforcement 2. 3.15d 34

Defective 2. 3. 5 31

Details —Batter 3. 5. le 159

Buoyancy 3. 5. 1f 159

Cast in place 3. 5. lh 160

Design loads 3. 5. 1d 159

General 3. 5. la 158

Limitation of use 3. 5. lb 158

Precast 3. 5. lg 159

Spacing, clearances and embedment 3. 5. 1d 159

Steel piles 3. 5. li 160

Steel pile and shell protection 3. 5. lj 161

Driver leads 2. 3. 4e 30

Extensions or "build-ups" 2. 3.16 35

Followers.... 2. 3. 4f 30

General requirements 3. 5. 1 158

Hammer for driving 2 . 3 . 4c 30

Loading tests 2. 3. 6a, c 31,32

Precast —Casting. 2. 3.13e 33

Class of concrete 2. 3.13b 33

Curing 2. 3.13g 33

Finish 2. 3.131 33

Form work 2. 3.13c 33

General 2. 3.13a 33

Handling and storage 2. 3.14 34

Measurement and payment 2. 3.18 3d

Placing concrete 2. 3.15 34

Projection in footings 3. 5. 1 158

Reinforcement 2.3.13d, 3. 5. lg 33, 159

Size and shape 3. 5. lg 159

Test piles 2.3.7, 2. 3.19 32,37

Water jets 2.3.4g, 2. 3. 6b 31,32

Piles, steel:Accuracy of driving 2. 3. 4h 31

Bearing values, formulas 2.3.6 31

268

Article Page

Bearing values, general 2. 3. 6 31CnrtK 2. 6. 6D -»Sfe:::::::::::::::... 2.3.3c 29Cutting off 2. 3.11 33Defective piles i. 6. a <uDesign— ...

Buoyancy g. &. "|°»Caps 3. 5. i 160

Core stoppers . • • . «. ». " ..General 2.3.2, 3. 5. la 29,158Loads ;. 3.4.1,3.4.17,3. 5. lc ....144,155,159Spacing, clearance, embedment 3. 5. 1d 159Splices 3. 5. h 1M)Thickness of metal 3. 5. li 160

Excavation 2. 3. 3a£9Followers 2. 3. 4f 30

Hammers for driving f. ». . j™Loading tests \. Va}\..Loads (for design) 3.4. ,3. 4.17 144, looMaterial 2.3.1,4 .13. 1 29,216Measurement and payment 2. 3 .18 6aOrder lists 2. 3. 8 J-Painting 2.3.3f,2. 3.17 30,35Preparation for driving

£. » . j|

Splicing|- |.

3e 29

wlt^S.v. :::::::::::2:3:4g,2: 3: eb :::: 31,32Piles, wooden:

„„Accuracy of cut-off£. IJ.1"Accuracy of driving 2. d. 4h .Ji

Bearing values, formulas o'„n\, ,„iBents 2.20.12 iu-Caps, driving'. 2. 3. 3b 29Collars, dnving

„ o c qiDefective 2. 3. 5 61Design loads 3 4.17 155Dimensions 4.25. 9 tioDriver leads

«' if SoFollower 2. 3. 4 30Hammer for driving 2. 3. 4b 30Handling and storage 2. 8. 9 66Heads, treatment of 2.20. 7 100Limitations of use 3. 5. lb is>»

Loading test, bearing value 2. 3. bb 61Payment conditions 2. 3.18 60Pointing 2. 3. 3dPreparation 2. 3 .3Preservatives 4.26. 1

^oPreservative treatment 2 .21. 1|«*Projection into footings 3. 5. 1d io»

Quality 4.2o. 8 234Sheet piles (see Sheet Piles).Splicing 2. 3. 3e 30

SSs/.:::::::::::::::::::::::::^^^: 3: 6b ...31,32(See also Timber, Lumber and Piles; Timber Structures.)

Pins, Pin Holes and Rollers : „ ,„ „. „„Boring pin holes 2 10.34 76Clearances 2.10.35 76Connections 2.10.55 80Fabrication 2.10.33 /b

269

Article

Holes 2.10.34, 3. 6.37Location, pins 3. 6.39Pilot and driving nuts 2 . 10 . 37, 2 . 10 . 55Pin nuts 3. 6.42Plates 3. 6.40Size 3. 6.18

Pipe Railing (see Railings and Parapets).Pipe, Sectional Plate (see Sectional Plate Pipe).Plans:

Contractor's approval . 1. 5. 2Coordination with specifications 1. 5. 4DefinitionDeviation from 1. 5. 3Examination 1. 2. 3Intent 1. 4. 1Working drawings 1. 5. 2

Plate Girders (see Steel Structures— Design and Details).Preservative Treatments for Timber :

Construction —Amount of preservative 2 . 21 . 4

Creosote 2.21. 4aSalt treatments 2.21. 4b

General 2.21. 1Limitations of treatments 2.21. 1Preparation for treatments 2.21. 3

Framing 2.21. 3bIncising 2.21. 3cSorting 2.21. 3a

Pressure treatment processes 2.21. 5Materials —

Chromated zinc chloride 4 . 26 . 1Creosote-coal -tar solution 4.26. 1Creosote oil 4.26. 1Creosote-petroleum solution 4 . 26 . 1Sodium fluoride-arsenate dinitrophenol solu

tion (Wolman Salts) 4.26. 1Zinc chloride 4 . 26 . 1Zinc meta arsenite (Z.M.A.) 4.26. 1

Property Protection and Restoration 1.4.8, 1. 7. 8

Proposal :

Competency of bidders 1. 2.11Contents of proposal form 1. 2. 1DefinitionDelivery 1. 2. 7Disqualification of bidders 1 . 2 . 10Examination of plans, specifications and site. .. . 1. 2. 3Form for 1.2.1, 2. 2. 4Guaranty (see Proposal Guaranty).Interpretation of estimates 1. 2. 2Preparation 1. 2. 4Public opening 1. 2 . 9Rejection 1. 2. 5Requirements and conditions Sec. 2Withdrawal 1. 2. 8

Proposal Guaranty:DefinitionForfeiture 1. 2. 6Return 1. 3. 3Submitted 1. 2. 7

Public Safety and Convenience 1. 7. 6

270

ArticleR

Railings and Parapets :

Concrete —Cast in place 2.13. 8

Expansion joints 2.13.11General 2.13. 6

Materials 2.13. 7Precast 2.13. 9

Surface finish 2.13.10Description 2.13. 1

Design 3.1.10, 3. 2.11Line and grade 2.13. 3Loading (live) 3. 2. lidMetal-

Construction 2.13. 4Materials 2.13. 2Painting 2.13. 5

Weight 2.10.62fPayment conditions 2 . 13 . 14Stone and brick 2.13.12Types and general requirements 3. 1.10Wooden 2.13.13

Ratings of Existing Bridges :

Columns —Batten plate 3.12.10Eccentrically loaded 3.12. 9

Long 3 . 12 . 9

Compression, flanges of beams and girders 3.12.11Dead load 3.12. 4Details of design —

Pins 3.12.12cSplices 3.12.12bStrength of connections 3 . 12 . 12a

Field inspection 3.12.13General 3.12. 1

Inventory ratings 3.12. 2

Live load 3.12. 5

Operating rating 3.12. 3

Stresses, unit 3 . 12 . 7Traffic lanes 3.12. 8

Wind load 3.12. 6

Reinforcement, concrete:Anchorage 3. 7. 9dBar 4. 5. 1

Bar deformations 4. 5. 1

Bar mat 4. 5. 3

Fabrication 2. 5. 4Material 2. 5. 1

Order lists 2. 5. 2

Payment conditions 2. 5.12Placing and fastening 2. 5. 7

Protection of 2. 5. 3

Splices and lapping 2.5.8, 2. 5. 9Structural shapes 4. 5. 4Substructure and retaining wall 3 . 5 . 2f

(See also Concrete Reinforcement.)Wire and wire mesh 4. 5. 2

Retaining Walls :

Base or footing slabs 3 . 5 . 4bCounterforts and buttresses 3 . 5 . 4dDrainage 3. 5. 4gExpansion and contraction joints 3. 5. 4f

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Article Page

General 3. 5. 4a 164Reinforcement for temperature 3. 5. 4e 165Vertical walls 3. 5. 4c 165

Right to Reject Bids 1. 3. 1 10Right of Way, definition 1. 1. 1 7

Riprap :

Concrete (in bags) 2.15.7, 2.15. 9 93Concrete slab 2.15. 8 93Dry 2.15.2, 2.15. 3 91

Foundation protection 2.15. 6 92

Grouted 2.15. 5 92Material 2.15.1, 4.20. 3 91,227Measurement and payment 2.15.11 93

Mortared 2.15. 4 92Placing 2.15.10 93

Rivets (see Steel and Steel Structures).Roadway :

Access to abutting property 1. 6. 3 16

Clearances 3. 1. 8 122Curbs 2.20.19, 3. 1. 9 .104, 122Definition 1. 1. 1 7

Drainage 3.1.11, 3. 8. 7 124,201Opening to traffic 1. 7. 6 17

Width-Bridges, Figs. 1 to 4 3.1.7, 3. 1. 8 122Depressed roadways 3. 1.17 126Depressed roadways —

Clearance 3. 1.17b 126Curbs 3. 1.17c 126Roadway width 3. 1.17a 127

Minimum required, Figs. 1 to 3 . . 3.1.7,3.1.8, 3. 1 . 17 122, 126Tunnels, Fig. 3 3. 1.16 125Underpasses 3. 1.18 126

Rolled Plates and Shapes :

Angles, effective area 3. 6.13 169Angles, minimum size (bracing) 3. 6.66 180Angles, outstanding leg 3. 6.17 170Beams 3. 6. 8 167Thickness of metal 3. 6.14 169

Rollers 2.10.33,3.4.2, 3. 6.51 76,145,177Rubble Masonry:

Arches —Arch rings 2. 7. 8 66Backing 2. 7. 8 66General 2. 7. 8 66

Copings, bridge seats and backwalls 2.7.7, 2. 7. 8 66

Description 2.7.1, 2. 8. 1 65,67Dry rubble masonry 2 . 8 . 1 67Headers 2.7.4, 2. 8. 4 65,67Laying 2.7.6, 2. 8. 6 65,67Material 2.7.2,2.8.2,2.20.1, 2.20.2 ....65,67,98,99Mortar rubble masonry 2. 7. 1 65Measurement and payment 2.7.10, 2. 8. 8 67,68Pointing 2. 7. 9 67Shaping of stones 2.7.5, 2. 8. 5 65,67Size of stones 2.7.3, 2. 8. 3 65

S

Safety, public 1. 7. 6 17Sand, for mortar 4. 3. 2 212

272

Article Page

SandblastingSanitary ProvisionsSectional Plate Arches:

Construction —Description, generalDescription of platesErectionForming and punching plates

MeasurementPaymentSubstructure and headwallsWorkmanshipDesign —

Adjustment of tableBoltsGage of platesGeneralMinimum height of coverMultiple spansRatio, rise to spanSkewed spansSubstructure

Material—Base metalBoltsCertified analysis and guaranteeChemical analysis and tests for spelter coat

ingCorrugationsField inspection and acceptance of plates . . .

Gage determination and toleranceGalvanizingIdentificationNuts and bolt headsSamplingSpelter coating

Sectional Plate Pipe :

Construction —Description, generalDescription of platesErectionForming and punching platesMeasurementPaymentStruttingWorkmanship

Design —BoltsCover exceeding heights in Table 1

Gage of bottom platesGage of platesGeneralMinimum height of coverMultiple pipes —spacingSize of pipe not in tableStrutting

Material —Base metalBoltsCertified analysis and guarantee

2.14.10c 891. 7. 5 17

2.23. 1 1082.23. 3 1092.23. 6 1102.23. 4 109

2.23.10 1132.23.11 1132.23. 8 1ll2.23. 9 1ll

3.11. 5 2063.11. 6 2063.11. 2 2063.11. 1 2063.11. 4 2063.11. 7 2073.11. 3 2063.11. 7 2073.11. 8 207

4.19. 1 2244.19. 8 2264.19. 6 225

4.19. 5 2254.19.10 2264.19.12 2264.19.11 2264.19. 3 2254.19. 7 2254.19. 9 2264.19. 4 2254.19. 2 224

2.23. 1 1082.23. 3 1092.23. 5 1092.23. 4 1092.23.10 1132.23.11 1132.23. 7 1ll2.23. 9 1ll

3.10. 5 2053.10. 6 2053.10. 4 2053.10. 2 2043.10. 1 2043.10. 3 2053.10. 8 2053.10. 7 2053.10. 9 205

4.19. 1 2244.19. 8 226

4.19. 6 225

273

ArticleChemical analysis and tests for spelter coat

ing 4.19. 5

Corrugations 4.19.10Field inspection and acceptance of plates ... 4.19.12Gage determination and tolerance 4.19.11Galvanizing 4.19. 3Identification 4.19. 7Nuts and bolt heads 4.19. 9Sampling 4.19. 4Spelter coating 4.19. 2

Sheet Metal:CopperLeadZinc

Sheet Piles:ConcretePayment conditionsSteelWooden

Sidewalk :

BracketsFinishLoadRailing (see Railings and Parapets).Width

Silicon Steel (see Steel, structural).Site:

ExaminationFinal cleaning upTemporary crossing

Slabs (see also Concrete Slabs and Girders).CantileverDistribution—

Reinforcement perpendicularEdge supportsMomentsShearSpan lengthsSupported four sides

Sodium Fluoride-Arsenage Dinitrophenol Solution(Wolman Salts)

Soils, bearing powerSpan lengths:

Concrete 3.3.2(i),Steel

Special Provisions :

CoordinationDefinitionExamination of

Special WorkSpecifications :

Coordination with plansDefinitionExamination ofIntentSilence of

4. 18. 1

4.18. 2

4. 18. 3

2. 2. 3

2. 2. 5

2. 2. 4,!2. 2. 2

3. 6.632. 4. 30

3. 2. 11

3 1 7

1. 2. 3

1. 4. 8

1. 4. 5

3. 3. 2f

3. 3. 2f3. 3. 3

3. 3. 2

3. 3. 2

3. 3. 2

3. 3. 2b3. 3. 23. 3. 2d3. 3. 2i3. 3. 28

4.26. 1

3. 4.15

3. 7. 4

3. 6. 3

1. 5. 4

1. 1. 1

1. 2. 3

1. 4. 2

1. 5. 4

1. 1. 1

1. 2. 3

1. 4. 1

1. 6. 5

1. 1. 1

1. 1. 1

274

ArticleSteel:

Castings —Carbon 4. 9. 1

Chromium -alloy 4. 9. 2

Malleable 4.11. 1

Copper bearing 4. 6. 8Forgings 4. 8. 1

General 4. 6. 1

Grid floor (see Bridge Floors).Piles 4.13.1,4.14. 1

Reinforcement (see Reinforcement, Concrete).Rivet-

High strength 4. 6. 7Structural 4. 6. 6

Sheet piles 4.14. 1

Structural —Carbon 4. 6. 2Low-alloy steel 3.4.7,4. 6. 4Nickel 4. 6. 5

Silicon 4. 6. 3

Structures (see Steel Structures).Tests-

Failure to meet requirements 4. 6.12Full size 4. 6. 9

Number and size of test bars 4.6.10Payment for full size tests 4. 6.14Record of annealing 4. 6.13Selection of test bars '. . . . 4. 6.11

Steel Structures :

Design and details—Alternating stresses 3. 6. 5

Anchor bolts 3. 6.53Angles, effective size 3. 6.13Arches, Solid Web :

Web plates for 3. 6.16Beams (composite) Sec. 9Bedplates 2.10.52Bolts 3. 6.43Bracing —

Deck plate girders 3. 6.69General 3. 6.65Half through trusses 3. 6.70Lateral . 3. 6.67Long columns 3 . 6 . 72Minimum size of angles 3. 6.66Portal and sway 3 . 6 . 68Through plate girders 3. 6.71

Closed sections and pockets 3. 6.28Columns —

Formulas 3.4.2, 3., 4., 5., 7., 3. 4. 8Formulas, Appendix B.

Combined stresses 3. 6. 6

Compression members 3. 6.15Cover plates (perforated) 3. 6.36Depth ratios 3. 6.11Eccentric connections 3. 6.29Effective area, angles 3. 6.13Expansion 3.6.46,3. 6.64Expansion bearings .3.6.47, 3. 6.48Fabrication, riveted unless otherwise speci

fied 2.10. 1

Fillers 3. 6.33

275

Article Page

Fixed bearings 3. 6.49 177Floor—Steel grid (see Bridge Floors).Floor system—

Cross frames 3. 6.58 178End floorbeams 3. 6.60 179End connections 3. 6.62 179End panels, skew , 3. 6.61 179Expansion joints 3. 6.64 179Floorbeams 3. 6.59 178

Sidewalk brackets 3. 6.63 179

Stiffness 3. 6.65 178Stringers 3. 6.57 178

Forked ends 3. 6.41 176

Gusset plates 3. 6.34 173

Inclined bearings 3. 6.52 177

Intermediate stiff eners 3. 6.80 182Lacing and perforated cover plates 3. 6.36 174

Limiting length of members 3. 6. 9 167

Loads (see Loads).Minimum thickness of metal 3. 6.14 169

Name plates 2.19.1, 3. 6.54 97,178Net sections, riveted members 3. 6.38 175

Outstanding legs of angles 3. 6.17 170

Parts accessible 3. 6.27 171

Payment conditions 2.10.58 80

Pedestals and shoes 3. 6.50 177

Pin holes, net section at 3. 6.37 175

Pin plates 3. 6.40 176

Pins and pin nuts 3. 6.42 176

Pins, location of 3. 6.39 175

Pins, size of 3. 6.18 170

Plate girders—Camber 3. 6.85 183

Depth 3. 6.104 186

Flange —Rivets 3. 6.76 182

Section 3. 6.74 181

Splice 3. 6.77 182

General 3. 6.73 181

Masonry bearings 3. 6.84 183

Sole plates 3. 6.83 183

Stiffener, transverse, end 3. 6.79 182

Stiff eners, transverse, intermediate 3. 6.80 182

Stiff eners, longitudinal 3. 6.81 183

Through, ends of 3. 6.82 183

Web plates, thickness 3. 6.75 181

Web splices 3. 6.78 182

Plates in compression 3. 6.15 169

Plates for arches (Solid Rib) 3. 6.16 170

Rivets :

Deduction for net section 3 . 6 . 38 175

Edge distance 3. 6.24 171

Lone grip 3. 6.25 171

Pitcn 3. 6.20 170

Pitch 3.6.21, 3. 6.22 170,171Size of 3. 6.19 170

Stitch 3. 6.23 171

Tension 3. 6.26 171

Rolled beams 3. 6. 8 167

Rollers 3.4.2,3.4.7,3.4.8,3.6.51 ....145,146,177

276

Article Page

Secondary stresses 3. 6. 7 167Sleeve nuts 3. 6.45 176Splices 3. 6.31 172Splices, indirect 3. 6.32 172Stay plates 3. 6.35 173Stiffener, plate girders 3.6.79,3.6.80, 3. 6.81 182,183Strength of connections .» 3. 6.30 179Symmetrical sections 3. 6.12 162

Thickness of metal 3. 6.14 169Trussgs—

Bottom chords 3. 6.88 184Camber 3. 6.90 184Counters 3. 6.92 184Diaphragms 3. 6.95 185Eyebars 3. 6.93 184General 3. 6.86 183Half -through 3. 6.70 180Masonry bearings 3. 6.97 185Riveted tension members 3. 6.91 184Sole plates 3. 6.96 185Top chords and end posts 3. 6.87 184Working lines and axes 3. 6.89 184

Trusses and girders—Effective depth 3. 6. 4 167Effective span 3. 6. 3 166Number 3. 6. 1 166Sidewalk brackets 3. 6.63 179Spacing 3. 6. 2 166

Upset ends 3. 6.44 176Viaducts —

Bents and towers —Batter 3. 6.100 185Bents and towers 3. 6.99 185Bottom struts 3. 6.103 185Bracing 3. 6.102 185Single 3. 6.101 185

Girder connections, bracing 3. 6.105 186Girder 3. 6.105 186Sole and masonry plates 3. 6.106 186Types 3. 6.98 185Welding 3. 6.55 178

Erection —Assembling steel 2.10.53 79Bearings and anchorages 2 . 10 . 51 78Bedplates, setting 2.10.51 78Bolted connections 2.10.18 72Camber diagram 2.10.13 71

Delivery of material 2.10.47 78Erection of structure 2.10.47 78Falsework 2.10.49, 2.10.57 78,80Handling and storing material 2.10.48 78Methods and equipment 2.10.50 78Misfits 2.10.56 80Old structure, removal 2 . 10 . 57 80Pin connections 2.10.55 80Plans and shipping statements 2.10.45 77Plant . 2.10.46 78Riveted connections 2.10.54 79Straightening bent material 2 . 10 . 52 79Work to include 2.10.44 77

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Article

.. 2.10.59

.. 2.10.62(i) to (8).

.. 2.10.5959,4. 6.14.. 2.10.60.. 2.10.61

Inspection and tests-Facilities for 2.10.39Full size tests 4. 6. 8Inspector's authority 2.10.40

Materials —Annealing eyebarsAnnealing recordFailure to meet requirementsMill ordersNumber and size test barsStorageStraightening 2.10.4,2Test bars and test eyebars 4Weighing finished pieces 2

Payment conditions —Basis of paymentComputed weightEyebars, testedFull size testsPay weightVariance in weight . .

Workmanship and fabrication —Abutting jointAnnealingAssembling, shopBearing surfacesBent plates 2.10.29Bolts and bolting —

Field connections 2.10.18Field connections—

Special ribbed boltsTurned boltsUnfinished bolts . . .

Fitting upCamber diagramEnd connections angles ....EyebarsField rivetsFinishFinished membersFit of stiffenersFlame cuttingHandling finished material .

Lacing barsMarking and shippingMatch markingMilled and planed surfaces—

Abutting joints 2.10.24End connection angles 2.10.25Facing bearing surfaces 2 . 10 . 23Planing sheared edges 2 . 10 . 20

Paints and painting (see Paints and Painting).Pilot and driving nuts 2 . 10 . 37Pins (see Pins, Pin Holes and Rollers).Punched, reamed and drilled —

Accuracy of drilled holes 2 . 10 . 11

Accuracy of punched and sub -drilledholes 2.10.10

2.10.112.10.14

2.10.6,2.10. 8

2.10. 7

2.10.324. 6.134. 6.122.10.414. 6.102.10. 3

10.526.10

10.42

81

.. 2.10.24

.. 2.10.3212,2.10.53 71

2.10.23

. 2.10.18d

. 2.10.18c

. 2.10.18b

. 2.10.18

. 2.10.13

. 2.10.25

. 2.10.31

. 2.10.172,2.10. 5

. 2.10.27

. 2.10.30

. 2.10.22

. 2.10.48

. 2.10.26

. 2.10.43

. 2.10.15

Accuracy of reamed holesDrifted holesDrilled holesPunched holes

278

Article Page

Punched workReamed workReamingReaming, field connectionsSub-punched holes

Rivets and riveting-FieldField connectionsRiveting

10.6,2.10.2.10.2.10.2.10.2.10.

9

8

99

9

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864330442821

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3

2

2.102.102.102.10

(See also Design and Details; Unit StressesRollers (see Pins, Pin Holes and Rollers).Screw threads 2.10.Shipping 2.10Stiff eners, fit of . . 2.10.Upset ends 3 . 6Web plates 2.10Welds 2.10.

Stone for Masonry :

Ashlar 2.6.3,4.20.Riprap 4.20.Rubble 4.20.(See also Ashlar Masonry; Rubble Masonry.) '

Stresses:Alternating 3. 6.

Combined 3. 6.Concrete piles (due to handling) 3. 5.Moments 3. 4.Secondary 8. 6.Sheets 1. 5.Steel structures-

Carbon 3. 4.Cast iron 3 . 4 .Cast steel 3.4.Column formulas. . . . .3.4.2, 3.4.7,3. 4.Column formulas (Appendix B)Low-Alloy 3. 4. 7Nickel 3. 4. 8Rivets 3. 4. 2Rivets (high strength) 3. 4. 3Silicon 7 3. 4. 8Welding 3. 4. 9Wrought iron 3. 4. 4

Timber-Column formulas 3. 4.14Column formulas, round columns — 3. 4.14dColumn formulas (connector joined) 3. 4.14cHorizontal shear 3 . 4 . 14aInclined surfaces, bearing 3. 4.14fNotched beams 3 . 4 . 14eTimber connectors 3. 4.14gTreated 3. 4.13Untreated 3. 4.13

Unit stresses —Bearing on masonry 3. 4.10Bronze 3. 4. 6Concrete structures —

Concrete 3. 4.11Reinforcement 3. 4.12

Copper-alloy 3. 4. 6General 3. 4. 1

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279

ArticlePiles, design load—

Concrete 3. 4.17Steel 3. 4.17Timber 3. 4.17

Reduction (load in combination) 3. 4. 1

Soils, bearing power 3. 4.15Structural Steel (see Steel).Structure :

Existing 1.4.6,2.10.58Temporary, definitionTemporary, removal 1. 4. 6

Sub-contractor, definitionSubstructure :

Anchor bolts in 2.10.51,3. 52b, 3 . 6 . 53

DefinitionDistribution of pressure 3. 5. 2cDrainage 3. 5. 4gIce breakers 3. 5. 5

Piles (see Foundations and Substructures).Scour protection 2.15.6,3. 5. laTubular steel piers (see Tubular Steel Piers).

Substructures and Foundations (see Substructures andFoundations).

Superintendent, competence of 1 . 5 . 5, 1 . 8 . 4

Superstructure :

Anchor bolts, setting 2 . 10 . 51

Bedplates 2.10.51Definition 1 . 1 . 1

Surety, definition 1. 1 . 1

Surface Finish, concrete 2. 4.23Suspension of Operations 1. 8. 5

T

Tables of Moments, Shears, etc. Appendix ATemporary Structures :

Construction and maintenance 1. 4. 5

Definition •

Removal 1. 4. 6

Terms, definition of 1 . 1 . JThermal Force 3. 2.15Timber Cribbing :

Construction —Face logs of timbers 2 .22 . 4cFilling 2.22. 5

Foundation 2.22. 4aMaterial 2.22. 1

Mudsills 2.22. 4bTies and fastenings 2.24. 3, e

Materials —.

Dimensions 2.22. 3

Preparation 2.22. 2

Payment condition 2.22. 6

Timber, hewn and round 4.25. 4Timber, Lumber and Piles :

Grading of yard lumber 4.25. 3

Grading, structural timber —General 4.25. 5

General requirements 4.25. 6

Limitation of use 4.25. 2

Species of woods 4.25. 1

280

ArticleStructural beams and stringers —

Stress—grades and working stresses 3. 4.13Structural joist and plank —

Stress—grades and working stresses 3 . 4.13Structural posts and timbers —

Stress—grades and working stresses 3. 4.13Timber piles—

Dimensions 4.25. 9

General 4.25. 7

Quality 4.25. 8

(See also Piles —Wooden.)Treated (see Preservative Treatment for Timber).

Timber preservative oils 4.26. 1

Timber structures :

Application of grades and sizes 4.25. 5

Beams (composite) 3. 9. 1

Bracing 2.20.15, 3.85e, 3. 8. 6e

Bridging 2.20.16Caps 2.20.14Columns and posts—

Connector joined 3.4.14c, 3. 8. 4

Design 3. 8. 4Formulas 3. 4.14Stresses 3. 4.13

Connectors —Construction 2.20. 2

Design 3. 4.14Material 4.27.1-4.27. 6

Countersinking 2.20.10Cribs (see Cofferdams and Cribs; also Tim

ber Cribbing).Drainage 3. 8. 7gErection, housing and railings 2.20.22Fire stops 3. 8. 8Formulas —

Axial compression on connector —joined spaced columns 3. 4.14c

Axial compression in rectangular columns 3. 4.14b

Bearing on inclined surfaces 3 . 4 . 14fHorizontal shear in rectangular beams . 3.4. 14aNotched beams 3 . 4 . 14eSafe load on round columns 3. 4.14dTimber connectors 3. 4.14g

Framed bents—Bracing 2.20.15, 3. 8. 5e

Caps 3. 8. 5dFramed bents 3. 8. 5bPile bents 3. 8. 5aPile bent abutments 3 . 8 . 5fSills and mud sills 3. 8. 5cCaps 2.20.14, 3. 8. 5

Mudsills 2.20.13a, 3. 8. 5

Pedestals, concrete 2.20.13bPosts 2.20.13d,3.8.4, 3. 8. 5

Sills 2.20.13c, 3. 8. 5cFraming 2.20.11Hewn and round timbers 4.25. 4Holes, bolt, dowel and lag screw 2.20. 8

Lumber and timber 2.20. laMetal parts —

Bolts and washers 2.20.9, 3. 8. 1

281

Article Page

Castings 2.20.1c, 3. 8. 6a 99,200Eyebars 2.20.1b, 3. 8. 6d 99,201Hangers 3. 8. 6c 201Hardware 2.20. Id, 3. 8. 3 99,199Structural shapes 2.20.1b, 3. 8. 6 99,200

Painting 2.20.23 104Payment conditions 2.20.24 104Pile bents 2.20.12, 3. 8. 5f 102,200Pile bents, abutment 3. 8. 5f 200Pile heads, treatment 2.20. 7 100

Fabric covering 2.20. 7c 101General 2.20. 7a 100Zinc covering 2.20. 7b 101

Plank, laminated and strip floors (see BridgeFloors).

Railings 2.20.19, 3. 8. 7h 104,202Storage of material 2.20. 3 99Stringers 2.20.16 103

Treated timber —Bolt holes, treatment 2.20. 5 100Cuts and abrasions 2.20. 5 100Framing and boring 2.20. 5 100Handling 2.20. 5 100Pile heads, treatment 2.20. 7 100Temporary attachment 2.20. 5e 100

Trusses —Bracing 3. 8. 6e 201Bridging 3. 8. 7b 201Camber 2.20.20, 3. 8. 6f 104,201Drainage 3. 8. 7g 202Eyebars and counters (see Eyebars).Fire stops and curtains 3. 8. 8 202

Floorbeams 3. 8. 6b 201Flooring 3. 8. 7d 202Hangers 3. 8. 6c 201

Housing 2.20.21 104Joints and splices 3. 8. 6a 200

Nailing strips 3. 8. 7c 201

Railing. ...r 2.20.19, 3. 8. 7h 104,202Retaining pieces 3 . 8 . 7e 202Stringers 3. 8. 7a 201

Wheel guards 3. 8. 7f 202Unit stresses (see Stresses).Unsupported length, columns and posts ... . 3. 8. 4 199

Untreated timber 2.20. 6 100

Wheel guards and railings 2.20.19 104Workmanship 2.20.4,2.20.11, 2.20.20 ...100,102,104Washers 3. 8. 2 199

Town or Township, definition 1. 1. 1$

Traffic Lane 3. 2. 6 130

Trucks 3. 2. 7 130

Trusses :

Steel (see Steel Structures).Timber (see Timber Structures).

Tubular Steel Piers:Bracing 3. 5. 6f 166

Depth 3. 5. 6b 166

Details 3. 5. 6 165

Piling 3. 5. 6c 166

Use of 3. 5. 6a . : 165

282

Article

Tunnels:Clearance between walls 3. 1.16bClearance, vertical 3. 1.16dCurbs, minimum width 3. 1.16cWidth between curbs 3. 1.16a

UUnderpasses :

Clearance, vertical 3. 1.18bCurbs, minimum width 3 . 1 . 18cWidth between curbs 3. 1.18a

Unit Stresses (see Stresses).Utilities, provision for 3. 1.15

VViaducts :

Concrete (see Concrete Viaducts).Steel (see Steel Structures— Viaducts).

w

Warning Signs and Barricades 1.4.5, 1. 7 . 7

Water:Concrete and mortar 4. 2 . 1

Sampling 4. 2. 2Tests 4. 2. 2

Waterproofing :

Application —Damage patches 2.17. 7

Details 2.17. 6

General 2.17.1, 2.17. 5

Arches (see Arches).Materials —

Asphalt 2.17.2, 4.22. 5

Fabric 2.17.2, 4.22. 7Inspection and delivery 4.22.11Joint filler 4.22.10Pitch 4.22. 6

Tar 4.22.8, 4.22. 9Payment conditions 2 . 17 . 9

Preparation of concrete surfaces 2.17. 4Protection course 2.17. 8Storage of fabric 2.17. 3

Waterway Area (see Design).Waterway Restricted (see Design).Wearing Surface, allowance for (see Loads).Wearing Surfaces (see Bridge Floors).Weight of Materials 3 . 2 . 2

Welding:Construction 2.10.21Design 3. 6.55General 3 . 6 . 55

Material 4.17. 1

Specifications 3. 6.55Stresses 3. 4. 9

Wheel Guards and Curbs 2.20.19,3.1.9, 3. 8. 7fWind Loads (see Loads).Wolman Salts 4.26. 1Wood, Wooden (see Timber, Lumber and Piles ; also

Timber Structures).

ArticleWood Preservatives:

Material (see Preservative Treatment for Timber).Work, definition 1 . 1 . JWorking Day, definition 1. 1 . 1

Workmen, competence of 1 • ° • 4

Wrought Iron :

Plates 4. 7. 1

Shapes and bars 4. 7. 2

Pipe. 4. 7. 3

Z

Zinc Chloride 2.21.1, 4.26. 1

Zinc meta Arsenate (Z.M.A.) 2.21.1, 4.26. 1

284

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.A6 American Association ofState Highway

Officials .

Standard specificationsfor highway bridges

tf. Of M. FLINT COLLFGF LIBRARY

Standard Specifications for Highway Bridges AASHO 1949 - Fifth Edition

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Transcript of Standard Specifications for Highway Bridges AASHO 1949 - Fifth Edition