Connections for Tilt Up Walls

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Connections for Tilt-Up Wall Construction

Transcript of Connections for Tilt Up Walls

Page 1: Connections for Tilt Up Walls

Connections for Tilt-Up Wall Construction

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Library of Congress Catalog Card Number 87-062384ISBN 0-89312-086-3

(0 Portland Cement Association 1987

This publication is based on the facts, tests, and authoritiesstated herein. It is intended for the use of professional per-sonnel competent to evaluate the significance and limitationsof the reported findings and who will accept responsibilityfor the application of the material it contains, The PortlandCement Association disclaims any and all responsibility forapplication of the stated principles or for the accuracy of a“Yof the sources other than work performed or informationdeveloped by the Association.

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Combined Shear and Tension . . . 24Steel Design . . . . . . . 24Wood Design ................................................................... 24

ConnectionDetaila . 25Detail Drawings with Commentary, Advantages,Disadvantages, and Restraints for

Wall Panel m Foundation Connections 25Trenched Footing/Wall Connection 25Footing/Wall Connection with Exterior

Dowels . . . . . 25Wall Panel to Floor Connections 26

Slab on Grade/Wall Connection . 26Precast Double Tee/Wall Connection

with Ledge . . 26Wood Joist/Wall Connection with Joist

Hanger on Wood Ledger . . . 27Heavy Timber Beam/Wall Connection

with Steel Shoe ............ ................................... .. ... 27

Wall Panelm Roof Connections 28Precast Double Tee Roof/Precast Beam/

Wall Connections ........ .................... ...................... 28Precast Double Tee Roof/Wall Connections ..............28Precast Double Tee Roof/Bearing on Wall

Connection .............................................. .. ...... ..... 29Precast Hollow-Core Roof/Bearing on Wall

Connection .............................................................. 29Steel Girder/Pilaster/Wall ConnectIons 30Steel Girder/Wall Connection with

Recessed Pocket . . 30Steel Girder/Clip Angie Wall Connection ..................31Steel Joist/Wall Connection with Seat Angle .............31Metal Deck/Wall Connection 32Wood Joist/Wall Connection with Wood

Ledger ..................................................... .. ... ......... 32Wood Joist/Wall Connection with Joist

Hanger on Wood Ledger . 33Wood Joist/Wall Connection with Joist

Hanger on Panel Top .. . ..................... .................... 33Plywood Roof Deck/Wall Connection with

Wood Ledgeron Panel Top . . 34

Wall Panel to Wall Panel Connections . 34h-Plane Wall/Wall Connection with Steel

Embedments ...... ...... .. ........................ ...... ........... 34In-Plane Wall/Wall Connection with

Threaded Inserts ................... ..................... ........... 35In-Plane Wall/Wall Connection with

Slitted Pipe ................. ......... .................................. 35Corner Wall/Wall Connection with Steel

Embedments ..... ................ .. ... ............. .. ............. 36Corner Wall/Wall Connection with Threaded

Inserts ................ .................................. .. ............... 36In-Plane Wall/Wall Connection with

Continuous Steel Chord 37In-Plane Diaphragm Chord Wall/Wall

Connection ...... ................ ..................................... 37Wall Panel to Steel Column Connections 38

Steel Column/Wall Connection with BoltedSteel Angles .................... ... ................ ... ............ . 38

Wall/Steel Column/Wall Connection withBolted Steel Angles ....... .......... .............................. 38

References .............................. ...... ............. ...... ........ 39

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Figures Tables

1.2.

3.4.5,

6.

7,

8.

9.

10,11.12,

13.

14,15,

Typical application of embedded bolts . . . . .. . 7Coil bolt and continuously threaded coil rod . 8Typical ferrule nut and inserts . .. . . . . 9

Typical coil nuts and inserts ..................................... 9Expansion inserts .. . . . . . . . . . . . . . 10Typical steel embedments with beaded

stud anchors .......................................................... 11Typical steel embedments with deformed-

bar anchors ............................................................ 11Development of concrete pullout cone for a

single stud subject to tension . . . . . . . . 11Typical welds between reinforcing bars and

structural steel shapes . . . . . . . . 12Typical welds of reinforcing bars . . . . . 12

Application of dowels as alignment pins . . . . . 13Design of structural-grade elastomeric bearing

pads . . . . . . . ... . . . . . . . . . . 15Application of frustum to find ,41 in stepped

or sloped suppnrts . ... . .. . . . .. . . . 16Shear lnading on a stud near a free edge . . . .. 17Stud groups in thin sections under combined

tension and moment . . .. . . . . . . . . 24

1. Allowable Working Stresses and Loads nnStandard Bolts (ASTM A 307) andThreaded Rods (ASTM A 36) . . . . . . . 8

2. Working-Load Capacity of Coil Bolts andThreaded Coil Rods . .. . . . .. .. .. . . 9

3. Development Length for Reinforcing Bars andDeformed-Bar Anchors . . .. .. . . . . . . 12

4. Coefficients of FAction for Shear-FrictionConnection Design . . . . . . . . . . .. 17

5. Design Shear Strength of Single-HeadedStuds .. . .. . .. .. . . . . . .. . . . . . . .. 17

6. Design Tensile Strength of Single-HeadedStuds . . . . . . . . . . . . . . .. . . . 18

7, Design Tensile Strength ofa Stud Group—Away from a Free Edge . . . . .. . . . . . . 19

8. Design Tensile Strength ofa Stud Group—Near a Free Edge on One Side . . . . . . . 20

9, Design Tensile Strength of a Stud Group—Near a Free Edge on Two Opposite Sides . . . . 21

10. Design Tensile Strength of a Stud Group—Near Free Edges on Two Adjacent Sides . . .. 22

11. Design Tensile Strength of a Stud Group—Near Three Adjacent Free Edges . . .. .. . 23

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Acknowledgments

The original manuscript for this publication was aninternal report of a research project for the PortlandCement Association. Authors of the report were JamesJ. Julien, Donald M. Schultz, Timothy R. Overman,and Khosrow Sowlat, all with the Structural Engineer-ing Section of Construction Technology Laboratories,Inc.

A large portion of the material found in chaptersconcerning materials, fabrication, and design wasgleaned from References 1, 2, and 3. Details shown inthe section of this document entitled “ConnectionDetails” were, in large part, obtained from engineersand contractors experienced in tilt-up construction anddesign. The designers and contractors that provideddetails are listed below

Al Shankle Construction Company, Anaheim,California

American Buildings Company, Eufala, AlabamaArmco Building Systems, Cincinnati, OhioThe Burke Company, Sacramento, CaliforniaDayton Superior, Miamisburg, OhioDominion Construction Company, Vancouver,

British Columbia, CanadaThe Haskell Company, Jacksonville, FloridaK, M, Kripanarayanan, El Monte, CaliforniaLockwood, Jones, and Beal, Inc., Dayton, OhioRichmond Screw Anchor Company, Fort Worth,

TexasWilliam M. Simpson, Newport Beach, CaliforniaSteinbecker and Associates, Dayton, Ohio

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A~= Cross-sectional area of steel stud shank, sq in. x, Y= Surface dimensions of assumed failure planeA,= Tensile failure surface area of the flat bottom around stud group, in.

of the base, sq in. A = Shear deformation, in.A,= Tensile failure surface area of sloping sides, ?.= Correction factor related to unit weight of

sq in, concrete,4Pf= Area of shear-friction reinforcement, sq in. p = Coefficient of frictionA, = Loaded bearing area in concrete, sq in. @= Strength-reduction factorA2 = The area of the lower base of the largest frus-

tum of a pyramid cone or tapered wedge con-tained wholly within the support and havingfor its upper base the loaded area and havingside slopes of 1 vertical to 2 horizontal, sq in.

b = Length of concrete bearing area, in.B.= Nominal bearing strength of plain concreteC,, = Strength reduction factor for single-headed

studs located near a free edge equals

d~= Diameter of stud, i$d,= Distance from centroid of tbe embedded steel

to tbe concrete free edge, in.dh= Stud head diameter, in.~= Unfactored compressive stress, psi

f;= Specifiedcompressive strength of concrete, psij = ~~#mm tensile strength of the stud materi-

jf = Tensile stress level on base of failure surface,psl

f,= Tensile stress level on the sloping sides offailure surface, psi

j = Specified yield strength of steel, psiG = Shear modulus, psiG,= Long-term shear modulus = 0.5G, psi!.= Embedment length of stud, in.N= Unfactored axial tension

Pnc= Nominal tensile strength of headed stud gov-erned by failure in concrete

P., = Nominal tensile strength of headed stud gnv-erned by failure in steel

PU=Factored axial load on concrete members atgiven eccentricity

t = Thickness of single-layer bearing pad or thick-ness of each lamination in laminated pads, in.

t~= Total thickness of pad assembly, in.V= Unfactored vertical reaction

V.= Nominal shear strength ofreinfnrced concreteVflC=Nominal shear strength nf stud governed by

failure in concreteV.,=Nominal shear strength of stud governed by

failure in steelVu= Factnred shear fnrce at a concrete sectionw= Width ofconcrete bearing area, in.

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Introduction

Tilt-up concrete walls have been successfully used formany years in low- and mid-rise structures of all types.Tilt-up panels offeran efficient, economical alternativeto preengineered buildings. Since they are sitecast,transportation is eliminated and handling is greatlyreduced. These low-maintenance, fire-resistant wallsoffer high thermal energy savings. Architectural treat-ments are almost unlimited.

Among the important design features of tilt-up con-struction are the structural connections. The engineermust design connections based on strength, ductility,durability, and economy, Connections for plant-castconcrete are addressed in several publications(l,z.j)However, connections used in tilt-up are more varieddue to the use of steel and wood as well as concrete inthe floor and roof designs.

This bookk primary function is as a reference forconnections used in tilt-up construction. It includes acompilation of connection details presently used fortilt-up construction in the United States and Canada.

For those unfamiliar with tilt-up development, abrief history is included in this section. Other sectionsdiscuss specific aspects of design, portions of whichwere gleaned from Reference 1. Guidelines for designare based on the provisions in Reference 4 and experi-mental research.

The concluding section contains 28 architecturalperspectives of connections between wall panels androofs, floors, adjacent walls, and foundations. The de-tails wereobtained from designers of tilt-up and througha review of literature.

HISTORICALREVIEW

Tilt-up construction was introduced in North Americaaround the turn of tbe twentieth century. However, itdid not become popular until after World War 11(51Anarticle published by Robert Aiken@lin 1909 describesearly tilt-up walls for single-story military buildings.

From the start, tilt-up proved to be an efficientconstruction method. However, it entered a hdI thatlasted until after World War 11. In 1946 more tilt-upbuildings were constructed than in any other precedingdecade(j)Tilt-up became most popular in the commer-cial and industrial sector.

Tilt-up’s increased popularity in the 1950’sled to ademand for construction procedures and details. Col-lins recognized the information deficiency and wrote aset of three “Know How” booklets(7.g.g)Collins laterdeveloped a single manual that combined his threeearlier publications(lol Expansion of tilt-up continuedthrough the 1970’s and improvements broadened inscope. In 1979, ACI Committee 551 on Tilt-up Con-crete Construction was organized to study and reporton current practices and develop standards.

From this brief history, it is evident that tilt-up is agrowing industry. This book is intended to serve as adesign guide and encompasses concrete, steel, andwood structural systems.

TILT-UPWALLCONNECTIONS

Early literature includes many panel-to-panel connec-tion detailv however, little is found concerning meth-ods of connecting tilt-up walls to roofs, floors, orfoundations.

In the early 1970’s, the Prestressed Concrete Insti-tute (PCI) became involved in providing recommen-dations for connections of precast members. A PCIcommittee wrote a manual on the design of connec-tions for precast members that is currently being re-vised!l) The tilt-up industsy embraced applicable PCIrecommended guidelines. The following sections pro-vide the first guidelines that encompass a wide varietyof connections for tilt-up construction.

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Structural and Material Considerations

When designing connections, strength and serviceabil-ity criteria must be met. Details that are not properlyconsidered in design may result in costly constructiondelays or unsafe structures. The following is an over-view of important design criteria and materials thatshould be considered in connections for tilt-up wallconstruction.

DESIGNLOADS

Some design loads are obvious such as vertical liveand dead loads and lateral lnads due to wind, soilpressure, and seismic events. In connection design lessapparent loads such as temporary erection loads andvolume changes must also be considered. These con-siderations are addressed in References 11and 23.

Overly strengthened connections can introduce un-wanted restraints. The amount oflixity ofa connectioninfluences the load paths, which in turn affect otherelements of the structural system. Therefnre, an ap-proach that cnnsiders connections as an integral partof the structure must be used in design{Il]

Connections are often designed with the intent ofresisting only one type nf loading. For instance, aconnection that has a large tensile capacity but haslittle shear capacity to accommodate movement due tovolume changes fits in this category.

DUCTILITYOF CONNECTIONS

Ductile connections are those that exhibit an ability towithstand deformation and load beyond the initialyield. It is desirable to design connections to behave ina ductile manner so they can support loads if unex-pected forces occur and large deformations develop.

RESTRAINTTO VOLUMECHANGE

Shrinkage from drying, changes in temperature andcreep all cause movements in wall panels. Where Pos-

sible, it is advisable to design connections that willaccommodate all volume changes.

Shrinkage occurs due to drying nfthe concrete. Afterdrying, if immersed in water, it absorbs water andexpands, However, it does not return to its originalvnlume, Concrete also expands or contracts as theambient temperature increases or decreases, The coef-ficient of thermal expansion ranges from 3.2 to 7millionths per ‘F (5.7 to 12.8 millionths per “C), with5.5 millionths per oF (10millionths per ‘C) the accept.ed average(l3)Steel has a comparable expansion, Creepof cnncrete is a time-dependent volume change relatedto deformation under sustained load,

DURABILITY

Durability refers to a material’s ability to maintain itsstrength and serviceability throughout its service life,Exposure of connections to weather may fnster deteri.oration of the components and subsequent reductionin strength; therefore, proper protection is essential. Inclimates where freeze-thaw cycles occur, concreteshould have sufficient air entrainment. Connectionsincorporating wend must use treated wood. Exposedsteel components must be given protective coatings.

FIRE RESISTANCE

Codes dictating fire-protection requirements for struc-tural members address connections, The PCI manualon fire resistance of concrete structures suggestsusage of fire retardants such as intumescent mastic,mineral fibers,,and vermiculite materials, Intumescentmastic is a paint-on liquid that, when dry, foams underelevated temperatures. Mineral fibers are mixed withbonding agents and sprayed or troweled to provide afire barrier. Vermiculite and cement pastes are mixedtogether and applied by troweling or spraying. Thesemethods of protection are all acceptable. Specific ap-plication is left to the engineer’s discretion based onarchitectural or other considerations.

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Design Considerations to Ensure Efficiency

Efficientconnection designs consider fabrication meth-ods as well as other criteria. Connections must bedesigned to optimize construction time. Designs thatdo not evaluate the influence of connection details onthe overall erection plans can result in costly construc-tion delays.

DESIGNSIMPLICITY

It is often said that the best designs are the simplestones. A straightforward approach requiring simple fab-rication and erection methods is essential. BYreducingthe number of components for a connection, construc-tion economy and efficiencycan be enhanced.

REPETITIONOF DETAILS

Fast, efficient, economical wall-panel installation re-quires optimizing the number of details for connec-tions. Plates, angles, and reinforcing bars should bestandardized. Also, the number nf dMerent-size com-ponents should be minimized. For instance, if a plateis sized to a 9Win. (240-mm) width, if possible, use a10-in. (250-mm) plate. If a No. 3 reinforcing bar isrequired for one connection and a No. 4 bar requiredfor another, consider using all No. 4 bars,

Some connections that are detailed similarly may besubject to slightly different service conditions. For in-stance, one may be designed for a 10-kip load and asimilar connection designed for a 20-kip load. It maybe prudent to design both connections for a 20-kipload. It should be noted, however, that overly strength-ened connections may introduce undue restraints.

REINFORCEMENT

Connections with reinforcement should be evaluatedprior to construction to ensure feasibility nf fabrica-tion. Choosing the smallest bars allowable may helpalleviate congestion. Smaller bars also require shorterdevelopment lengths. To ensure adequate clearances

and proper dimensioning, scale drawings should beprovided.

EMBEDDEDSTEEL SHAPESANDTHREADEDINSERTS

Misalignment of embedded structural steel andthreaded inserts generally results in erection problems.Plates and angles with predrilled holes should be se-curely fastened to the fnrms. Threaded inserts must befirmly anchored or tied in place to prevent movementduring concreting, Anchoring or tying in place priorto concreting, rather than inserting the devices dur-ing concreting, ensures quality control with littlesupervision,

Where concrete must be placed under a horizontalportion of an embedded structuraLsteei component,holes should be provided in the component to avoidtrapping air under the embedment. In the case ofangles, the horizontal leg should be clearly marked sothat holes are made in the proper leg.

DIMENSIONS

Dimensions of all components of the connectionsshould be to the nearest half inch to simplify produc-tion. Plate dimensions should be standard widths.Clearances between reinforcing bars and other com-ponents should be at least equal to 11/3times themaximum aggregate size.

FORMWORK

Wall-panel forms should rest on a flat and level surfaceand be square and vertical. If an embedded angle isattached tn a skewed form, allowable tolerances maybe insufficient to accommodate the misplaced angle,Edge forms must be accurately positioned and firmlyanchored to prevent movement during concreting.

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Erection ConsiderationsAll phases oftilt-up design and construction are impor-tant for overall efficiency and economy of the project.Connection design is especially significant because ofthe time demands on skilled labor and equipmentduring erection. Connection locations are also impor-tant. Connections that can be made at ground level aregenerally more economical than assembly of connec-tions while working from a ladder. The following is abrief overview of the items a designer should consider.

CLEARANCESAND TOLERANCES

Inadequate clearances can impede construction andfailure to adhere to specified tolerances may effect thestrength of the connections, Although clearances andtolerances are important economic considerations,there currently are no published values specifically fortilt-up. The following suggestions are offered based nnpresent practices and the provisions noted in Refer-ence 1, the PCI manual. Architectural and structuraldrawings should specify clearances and tolerances.

As a rule, small clearances should be avoided. If alarger clearance is architecturally and structurally ac-ceptable, it should be used. The type of connectionoften governs the clearance needed. Using splice platesor clip angles to bridge the space between embeddedcomponents can accommodate large clearances, Cur-rent practice suggests that a minimum of 1/2 in. (12mm) and preferably 3/4in. (19 mm) be allowed betweenpanels. Larger clearance of 1 in. (25 mm) minimumand 2 in. (50 mm) preferred is recommended betweenstructural support members and panels.

Tolerances in the placement of embedded plates,angles, and inserts are also governed by the type ofconnections provided. In general, inserts to receivebolts must have lower tolerances than welded connec-tions. The following values are considered attainable

RecommendedItem tolerances, in.

Field-placed anchor bolts * 1/4

Elevation of footings or piers +1/2,–2

Position of bearing plates * 1/2

Position of embedded plates *IPosition of inserts f 1/2

Specified clearance space *3/8

Metric equivalent: 1 in. = 25,4 mm

FIELDWELDING

Field welding should not be used indiscriminately.Welded connections generally are quite rigid and mayfail when subjected to large unpredicted forces in ex-cess of design limits. Large forces can result fromvohrme changes discussed earlier. Consideration shouldbe given to employing a combination of bolting andwelding where more control of movement is possible.When only a few connections are to be welded, alter-nate methods should be explored for more economicalsolutions.

Applicable specifications and procedures for weldingstructural and reinforcing steel should be in compli-ance with AWS Designation D 1.1,Structural WeldingCode—Steel(IS) and AWS D1.4, Structural WeldingCode—Reinforcing Steel(’G]respectively.

Welders should adhere to erection drawings andprovide only specified amounts of weld to avoid caus-ing excess fixity. Connections should be designed toallow sufficient working space for welders. Avoidcramped and congested areas. Locate weld joints toDermit them to be done in the down-hand positionwherever possible.

Structural steel exposed to cold temperatures andreinforcim steel may require preheating prior tomaking tie weld. Ca~e sh&dd be taken to avoid anydamage to the surrounding concrete as a result of hightemperatures.

TEMPORARYCONNECTIONS

During erection of tilt-up panels, temporary bracing,guywires, or other means of support maybe required.Wherever possible, utilize the permanent connectiondevices rather than temporary built-in connections toattach tbe bracing. If this is not feasible, then tempo-rary connections must be provided for the bracing.They should be removed after final connections aremade in order to avoid unforeseen distress in thestructure.

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Conceptual Design

The following conceptual design considerations, al-though general in nature, are important to the overalltreatment of connection design.

LOADPATHS

Each structure with all its elements and connectionsshould be considered as an interdependent structuralsystem, Each connection is notan isolated element butrather part of an integrated system. An applied exter-nal load is dktributed through the structural system tothe foundation and supports through lnad paths. Loadpaths induce internal forces between elements of thesystem. An efficient design considers all possible loadpaths. This is done to optimize the number and mag-nitude of internal forces within a structural system inan effort to simplify the connections.

FAILUREMODES

The engineer should be aware of the potential modesof failure in each connection. Sufficient redundancyshould be provided to eliminate the potential for aprogressive collapse. Failure mechanisms are often ob-vious and easy to define, Failure modes that are diffi-cult to identify should be isolated by testing,(l)

Connections that subject concrete to tensile forcescan result in brittle failure modes. Unlike a ductilefailure, a brittle failure is usually sudden and withoutwarning, If a nonrigid connection cannot be provided,the engineer should account for this by increasing thesafety factor of the connection.

PLIANTCONNECTIONS

Low tliction materials allow a member to slip, thusaccommodating movement.

Connections can be “softened” through the use ofslotted holes in bolted connections. The bolt is tight-ened sufficiently to hold the member in place; however,the slot allows the member to move with little restraint,But if the connection is bolted tight against the endof the slot, movement is restricted. This should beavoided,

Rigid connections can be subject to unanticipatedstresses due to volume changes. As a result, they mayfail, An alternate to a rigid connection is one thatrelieves stress by allowing movement to occur. Flexi-bility can be attained in various ways. Bearing padssupporting structural members can offer stress relief.

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Connection Elements

Connection elements and materials commonly usedin tilt-up construction are discussed in the followingsections, These include standard bolts, threadedrods, headed studs, threaded inserts, expansion inserts,structural-steel shapes, deformed bar anchors, sitecastconcrete, welding, dowels, grout, and epoxies. A de-scription is given and applications, design considera-tions, and design data are discussed.

STANDARDBOLTSAND THREADEDRODS

Description

Standard bolts and threaded rods are medium-strengthmaterials, They are ductile and conform with the“stretch before breaking” philosophy of design. Stand-ard bolts conform to the American Society for Testing

Wall panel –,

Fig. 1. Typical application of embedded bolte.

and Materials (ASTM) Designation A 307, StandardSpecification for Carbon Steel Externally ThreadedFasteners.(171For threaded rods, the most commonmaterial conforms with ASTM A 36, Standard Specifi-cation for Structural Steel,t1s]Threading of bolts androds conforms to the American Standards Institute(ANSI) Bl,l, Unified Inch Screw Threads.tlg)

Applications

The most common applications for standard bolts is toconnect steel components. They are also used to con-nect steel shapes to concrete tilt-up walls. They areeither embedded in the concrete or threaded into in-serts anchored in the concrete. Fig. 1 illustrates atypical use of a bolt embedded in concrete. It shouldbe noted, however, that holding the bolt in place duringconcrete placement can be difficult. An alternate to thestandard fastener is a threaded steel rod and nuts. Boltor rod assemblies are an excellent solution for low-costconnections. They provide excellent anchorage for lightloads.

Design Considerations

Standard bolts and threaded rods are not adequate forfriction-type connections. Consider using high-strengthbolts where friction connections are needed. Note toothat the capacity of embedded bolts and threaded rodsmay be limited by failure of tbe concrete as well as inthe strength of embedded steel.

The mating elements of bolts—such as threadedinserts—must be accessible for easy placement andproper tightening. With threaded inserts, proper toler-ances must be provided,

DesignData

Table 1 provides tensile and shear capacities of boltsand threaded fasteners. Note the footnotes of the tablesconcerning the allowable tension and shear capacities.The American Institute of Steel Construction, Inc.,(AISC) Manual of Steel Comtruction(’”) contains ad-ditional information concerning design.

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Table 1. Allowabla Working Straaaaa and Loadaon Standard Bolta (ASTM A307) andThraadad Roda (ASTM A36) [Adaptad fromRafaranca 20]

Tension

‘Based on tensile strew on the nominal (gross) area of the bolt

Sin.\. she.”-. ..=.- . . .

-,Throadsnot includedinthe shear plane.St8el.to-steelconnections.Metric eq.lvalent8: 1 in, = 25,4mm, 1 tip= 4,45kN, t ksi = 6,89 MPa

HIGH-STRENGTHBOLTS

High-strength bolts are seldom used for connections oftilt-up panels, They are normally used only where steelcomponents are fastened together. They are reservedfor loading conditions with high tensile and shearstress requirements. High-strength bolts conform toASTM A 325, Standard Specification for High-StrengthBolts for Structural Steel Joints, Including SuitableNuts and Plain Hardened Washers\z]) or ASTM A 490,Standard Specification for Quenched and TemperedAlloy Steel Bolts for Structural Steel Joints,@ZJThread-ing conforms to ANSI B1.1.[19)

The common application for high-strength bolts is toconnect steel components firmly enough to preventseparation or sliding, Components are those that aresubject to large tensile and shear forces, The highstrength of the bolts provides sufficient compressionbetween tbe components to make a friction-type con-nection.

High-strength bolts are not embedded in concrete,since the pullout strength of the concrete controls thecapacity of the connection and high-strength steel isnot efficiently used.

DesignConsiderations

Placement and torquing of friction-type connectionsrequire strict quality control. Bolts must be accessiblefor each placement. Sufficient clearances are necessary

to torque the nuts and develop the tension in the bolts.In designing, it is important to know that the allow-

able shear on the bolts depends upon whether or notthe threads are in the shear plane..Refer to design datato determine the thread/shear plane effects.

DesignData

Design data, including standard bolt dimensions andallowable stresses and loads can be found in Reference20. Both bearing-type and friction-type connectionsare included. Both cases of inclusion and exclusion ofthreads in the shear plane are considered.

For frictinn-type connections, all mill scale must beremoved from the surfaces of connected materials. Thehole size is considered standard and is 1/16in. (1.6 mm)larger than the bolt, Oversize holes for friction connec-tions should not be permitted.

COIL BOLTSANDTHREADEDCOIL RODS

Description

Coil bolts and threaded coil rods are coarse-threadedfasteners for use with helically coiled inserts. The in-serts are discussed in the section “Threaded Inserts.”The bolts and rnds are available in standard diametersranging from lhto lYzin. (13t038mm) .Lengthsupto10 fi (3,1 m)areavailable. Atypical coil bolt and coilrnd are illustrated in Fig, 2.

Fig. 2. Coil bolt and continuouslythreaded coil rod.

Coil bolts and coil rods are used primarily for liftingand temporary connections. Coil bolts and coil rodsare not recommended for permanent connections inareas nfhigh-risk seismic zones.

DesignConsiderations

The mating elements of coil bolts and coil rods—suchas threaded inserts—must be accessible for easy place-ment and proper tightening. Sufficient tolerances mustbe provided.

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Where these threaded elements are used for liftingand temporary connections they are generalIy reusedmany times. As a result, the threads should be regularlyexamined for wear.

DesignData

Table 2 provides data on the tensile working load andthe shear working load capacity of coil bolts andthreaded coil rods, based on regular-strength material.The manufacturers of coil products can furnish capac-ities based on various-strength materials, includhghigh-strength materials. Generally, the safe tensileworking load is given as ?3 of the minimum tensilestrength, and the safe shear working load is 2/3of thesafe tensile working load.

Table 2. Working-Load Capacity of Coil Bolts andThreaded Coil Rods* [Adamed fromRafarence 3] -

Bolt diirneter, Tensile aJrangth, Tensile working Shear workingload, lb** load, Ibt

M 13,500 9,000 6,oOO

3/4 18,000 12,000 6,000

1 36,000 24,000 16,000

1% 54,000 36,000 24,000

1V, 72,000 48,000 32,000

‘Increase {actor of safety by reducing safe working loads... Ten$W WrHng load is % tensile capacity.Tshear working load Is % tensile worMng load.

Note A minimum of two threads beyond coil is required t. develop fullCapacily.

Metric equivalents: 1 l“. = 25.4 mm, 1 lb= 4.45 N

THREADEDINSERTS

Description

Ferrule Inserts. Ferrule inserts as shown in Figure 3are nutlike anchors. They are embedded in concretefor use with standard bolts having national standardcoarse threads, Steel-wire looPs are welded to each nutto provide better anchorage to concrete. They are avail-able in sizes ranging from !/4to 1‘/2in. (6 to 38 mm).

Coil Inserts. Coil inserts consist of helically woundcoil wire to fnrm a nutlike anchor into which a coilbolt or rod can be threaded. Welded to the inserts areone or more wires or wire 100PSthat provide anchorageto concrete. They are available in sizes 1/2to 11/2 in. (13to 38 mm). Fig. 4 illustrates different coil-insertdesigns.

Applications

Ferrule and coil inserts when properly imbedded inconcrete provide excellent means of establishing fast

(a) Ferrule ineerl nut

f“<

‘--%\

e

E<’$- =;+] ‘

(b) Ferrule inserfs

Fig. 3. Typical ferrule nut end ineerfe.

(a) Coil inseri nuts

u

9

Page 15: Connections for Tilt Up Walls

bolted connections in tilt-up panels. They are especial-ly useful for lifting and bracing connections.

DesignConsideretions

Ferrule and coil inserts rely nn the anchorage of thewire loops to provide the load capacity. Load is trans-ferred through the wires to the concrete. Their capacityis limited by either tbe pullout strength of the concreteor the tensile strength nf the wires, Placement of theinserts near a free edge reduces the load-carryingcapacity.

The engineer should determine the appropriateworking loads to be used based on the nature anddetails of the specific connection being designed.Threaded inserts fail in a brittle mode when the tensilestrength of the concrete is exceeded. Proper factors nfsafety must be provided to account for this nonductilebehavior, particularly in seismic design.

Design Data

A wide variety of ferrule and coil inserts are available.Test data and recommended allowable loads are read-ily available from the manufacturers. Usually, test dataand recommended allowable loads are fnr normal-weight concrete. If lightweight concrete is used, theallnwable loads should be reduced to reflect reducedcapacity.

EXPANSIONINSERTS

Description

Expansion inserts are anchors that are inserted intoholes drilled in hardened concrete. Radial expansionnf the insert exerts a force nn the walls of the hnle,providing ffiction and anchorage.

Either bolts or threaded rods are used with expan-sion inserts. A variety of expansion inserts availableare illustrated in Fig. 5.

Applications

Expansion inserts are most efficiently utilized for ret-rofitting misplaced nr left-nut cast-in-place concreteinserts. They are used mostly in temporary crmnec-tions and for bracing of tilt-up panels during erection.They are nnt normally recommended for permanentconnections.

DesignConsiderations

Strength of expansion inserts is developed as a resultof pressure against the walls of the drilled hole, Conse-quently, the distance between inserts and the orienta-tionof the insert with afree edge is critical. Embed-

1!—-!

--k-

Fig. 5. Expansion in9erts.

ment depths, size, and shape of the hole are alsocritical. Tight tolerances are required on the holesdrilled intheconcrete andon thetorque applied tobolts during installation of most expansion anchnrs.Snme expansion inserts require the use of calibratedtorque wrenches to control the torque andtn obtainproper expansion.

Dasign Data

It is recommended that test data and allowable loadvalues be obtained from the manufacturer, However,the engineer should determine the appropriate workingloads based on the nature and details of design.

STEEL EMBEDMENTS

Description

Typical steel embedments are shown in F[gs. 6 and 7.They are fabricated from multiple elements includingheaded studs, bnlts, deformed bar anchors, standardreinforcing bars, plates, and structural shapes,

Headed studs conform to ASTM A 108, StandardSpecification for Steel Bars, Carbon, Cold Finished,Standard Quality,{24)Reinforcing bars conform toASTM A 615,Standard Specification fnr Deformed andPlain Billet-Steel Bars for Cnncrete Reinforcement.@Sl

10

Page 16: Connections for Tilt Up Walls

Applications

Steel embedments are generally used at weldment lo-cations to make connections of wall panels to otherbuilding components. Typically, plates and angles arecast flush with the concrete surface along a flat face ora corner. They may be used along with splice platesor angles fitted for welding or bolting to adjacentmembers.

[-

DesignConsiderations

Lnads that can be resisted by steel embedments in-clude tension, compression, and shear, singly or in

_._._. . combination. When welding headed studs and de-

&

formed bars to plates, quality control is usually at-tained with the use of automatic stud-welding ma-chines. Hand welding requires careful control andrelies heavily on tbe skill of the welder,

A concrete pullout cone, as shown in Fig. 8, is thenormal failure mode associated with headed studs,Specific design considerations are dependent on thedetails and the location of the embedments with re-

Fig. 6. Typical steel embedments with heeded etud en- spect to a free edge. This is discussed in more detail inchors. the section “Connection Design.”

/-%

Fig, 8. Development of conrete pullout cone for a einglestud eubject to tension.

Design Data

Fig. 7. Typical steel embedments with defornred-ber an-chore.

Development lengths for tensile loads on deformed-bar anchors and reinforcement are given in Table 3.The lengths are based on values specified in Reference4. Welding is discussed in the following section.

Design data for headed studs is provided in thesection “Connection Design” along with a more de-tailed look at headed stud design.

11

Page 17: Connections for Tilt Up Walls

I(\

Tabla 3. Davelopmant Length, in., for ReinforcingBara and Deformad-Bar Anchors*[Adapted from Raference 4]

-

Normal-weight concrete Sand-lightweight concrote

5000 12 12 12 15 12 12 14 186000 12 12 12 15 12 12 14 187000 12 12 12 15 12 tz 14 188000 tz 12 12 t5 12 12 14 18

‘f, = 60,000 PSI;for values obow 60,000 PSImultiply by 2 – yY

Metric equivalents 1 In. = 25.4 mm, 1 Psi= 6.89 kPa

WELDING

Description

The most common types of welds used in tilt-up arefillet and groove welds as shown in Figs. 9 and 10.Thewelds are generally made by the shielded metal arc-weldlng process applied to structural-steel shapescontaining steel that conforms to ASTM A 36 specifi-cations and reinforcing steel that conforms to ASTMA 615 specifications.

Applications

Welds are commonly used to join steel elements toform steel embedments and to make connections be-tween structural members. Designed in proper config-uration, they can be made to resist tension, compres-sion, flexure, or torsion. Specific details for differentconditions are shown in the section “Connection De-tails” in this book.

DesignConsiderations

When welded connections are used, consideration mustbe given to their restraint of movement between theconnected parts. Welded connections are generally rig-id and are not recommended where large volumechanges are expected, When using welded connections,accessibility and proper procedures for welding mustbe considered. Welding should be performed in a down-hand position.

DesignData

The strength of welds depends on reliable workman-ship and the compatibility of welding materials withthe metals to be joined. An adequate presentation onthe requirements of welding is beyond the scope of this

14+7 P-l-

Fig. 9. Typical welde between reinforcing ber9 end struc-tural steel shepes.

Fig. 10. Typical weids of reinforcing bars.

12

Page 18: Connections for Tilt Up Walls

book. Complete details of structural steel welding aregiven in AWSD 1.1,Structural Welding Code—Steelfl’)and design of welds for reinforcement can be found inAWS D 1.4-79,Structural Welding Code—ReinforcingSteel.flcl

DOWELS

Description

Dowels are short lengths of steel rods or bars embed-ded in concrete,,welded to steel embedment plates, orgrouted into drdled holes.

Deformed dowels are cut from conventional steelreinforcing bars. Smooth dowels are cut from smoothbar stock.

Applications

A common application of deformed dowels in tilt-upis to connect wall panels to the building floor slab asshown in the section “Wall Panel to Floor Connecting,”A common application of smooth dowels is alignmentof wall panels as they are tilted and set on a footing orpier. This is illustrated in Fig. 11.

DesignConsiderations

Dowels connecting wall panels to floors can be provid-ed in various ways. Deformed dowels can either be setin place prior to concreting, welded to a plate embed-ment, or screwed into preset threaded inserts.

No+e: Pmw is moved flush OgOinstdowelpins f.r pr.per alignment

Fig. 11. Application of dowels as alignment pins.

The most common method of connecting panels toflnors is through the use of deformed dowels shapedand embedded entirely within the tilt-up panel. Afterthe concrete has hardened, the dowels are bent out-ward to their final position for splice lapping with floorreinforcement. This practice is limited to bars no largerthan No. 5.

Smooth dowels used for alignment of panels shouldbe positioned to meet a specified tolerance.

SAND-CEMENTGROUT

Description

Sand-cement grouts are a mixture of portland cement,sand, and water. Generally they have a high slump andare used for filling small voids where normal concretecannot be placed. Sand-cement ratios range between 1to 1and3to 1.

A low-slump grout may be used where high-slumpgrout cannot be held in place. Low-slump grouts aregenerally hand-tamped into place.

Applications

Sand-cement grout is generally used to fill the gapbetween the foundations and wall panels to transferthe bearing loads. Dowels placed in hnles that havebeen drilled in hardened concrete can be anchoredwith the use of grout.

DesignConsiderations

High-slump grouts with a water-cement ratio of O.5or greater may shrink excessively. Shrinkage can bereduced by using compensating admixtures. Themanufacturer’s literature should be reviewed and somemixes tested before construction begins.

Dry-pack grouts have a much lower water-cementratio; as a result, shrinkage generally is not a problem.Moist curing of the grout is recommended.

EPOXY

Description

An epoxy is a two-component system that when com-bined produces a material used for bonding. Epoxy-based bonding systems are addressed by ASTMC881,Standard Specification for Epoxy-Resin-Base BondingSystem for Concrete.<26JAdditives can protect epoxiesagainst moisture.

Applications

Epoxies can be used to connect structural and non-structural members including concrete, steel, alumi-

t3

Page 19: Connections for Tilt Up Walls

num, copper, and wood. They also provide a meansof field repair when mechanical connectors are notpractical.

Design Considerations

Although high tensile strengths can be achieved withepoxies, available data on response to cyclic loads islimited, Properties may change with time. Conse-quently, careful consideration should be given to eachapplication: Epoxies can have thermal expansion Ofupto seven times that of concrete. They also have alimited time during which they are workable, Temper-ature, humidity, and surface water may effect perfor-mance. It is recommended that design and use data nfthe manufacturer be thoroughly reviewed.

EPOXYGROUTS

Description

Epoxy grouts consist nf a two-component epoxysystem and an aggregate filler. Epoxy grouts are ad-dressed by the ASTM specifications given in the sec-tion “EPOXY:’(2Q

Applications

When high bond strength between concrete membersis required and a large amount of bonding agent isneeded, epoxy grout is an economical alternate tosimple epoxy. In tilt-up constructing, epoxy grouts areused mostly for grouting dowel connections.

Designconsiderations

Design considerations for epoxy grout are the same asfor epoxy as given in the section “Epoxy,” with someexceptions. With the addition of the aggregate filler,thethermal expansion ofepoxy grout can be reduced toabout twice that of concrete, The amnunt of aggregatefdleraffects the strength. Excessive aggregate contentreduces the bond strength.

BEARINGPADS

Daacription

5. Teflonpads6. Multipolymer-plastic bearing strips7, Tempered hardboard strip

Application

Bearing pads are generally used under simply support-ed members to distribute loads evenly over a bearingsurface. They are designed to allow some displacementand some rotation to nccur between the structuralmembers.

Design Considerations

Different types of pads are available to suit differentapplications. A material may be specified based oncompressibility, resilience, frictional characteristics, orresponse to environmental conditions, Pads are rela-tively simple and easy to install. However, they canmnve nut ofpnsitinn under repetitive loading. Also,they generally degrade when exposed to fire.

DesignData

Design requirements for structural-grade elastomericpads are illustratedin Fig. 12, Design data for othertypes are available from the manufacturer.

Bearing pads are intermediate elements between load-bearing structural members. They are available in avariety nf materials1. Structural-grade elastomeric (neoprene) pads2. Laminated steel andneoprene pads3. Laminated fabric andrubber pads4. Laminated synthetic fiber pads

14

Page 20: Connections for Tilt Up Walls

EmShear modulus, G,ps,

Des,gn D“rorneter4

V

temP 50 60 70

70° F 116 160 21520°F 121 176 236O-F 138 200 269

3 -20°F 209 304 408

:.>

//

rNote: For$haPe FaCtOr>4,

.s6 mm compressive

,Ires$ = 1000,$1

01 1 1 1 1 I

o 200 400 600 800 1000

Maximum compressive stress, psl (15%st rain)

a+’‘*N ‘h”pe’oc’:1. Useunfactored loads fordesign

2. Maximum comwessiva stress = 1000 psi3. Maximum shear stress= 100 psi

4. Maximum ahear deformation = t/25, Maximum compreaaive strain= 150/06. wz5tor4 in.7. t,2 V4 in. for stems, 3/8 in. for beams

Metric equivalents 1 in. = 25.4 mm, 1 lb= 4.45 N,1 psi= 6.89 kPa

Fig. 12. Design of structural-grade elastomeric beeringpade. (Reproduced from Reference 1)

15

Page 21: Connections for Tilt Up Walls

Connection Design

Design of connections for tilt-up requires considera-tion of strength and serviceability of all materials thatmay be affected, including concrete, steel, or wood. Forfurther requirements related to these materials, theappropriate codes should be consu]ted(4Z0,Z7)

Connections can subject concrete to tensile forcescausing a brittle, sudden failure withnut warning, Toreduce the possibility of a brittle failure, the strengthnf the steel embedment should control the design nfthe anchorage,

The following sections briefly describe some generalaspects of connection design that relate to the designconsiderations and design data included in the section“Connection Elements” and design details included inthe section “Connection Details:’ El

——————\ <145.

n

L00d9d45. I

oma

/ \

/ ‘,J

I

Plan

BEARINGON PLAINCONCRETE

Nearly all connections of precast concrete involve thebearing strength of concrete, The ACI Building CndecJ)limits the unit design bearing stress to

CDBn= @(0,85f&A1)- Eq. 1

The relationship - is limited to a maximumof 2. Fig. 13describes A2.

e’Elevation

Fig. 13. Application of frustum to find A, in stepped orsloped supports.

SHEAR

Shear-FrictionDasign UsingHeaded Studs

The shear-friction concept is cnmmonly used in thedesign of connections between precast elements. Inshear-friction design, the nominal shear strength of theconnectiorr(l.d)with # from Table 4 is

However, in light of some recent tidings, the useof the shear-friction concept is questionable whenheaded studs are involved. If the shear-friction conceptis used fnr special situations, adequate safety factorsshnuld be applied.

Shear Strengthof Headad Studs (Tabia 5)

No rational model, including shear-friction, currentlyexists to accurately determine the capacity of headedstud connections. As a result, empirical equations arepresented in this section to predict the capacity, Theempirical equatinns from Reference 28 were used tocalculate the values in Table 5 that are governed by

16

Page 22: Connections for Tilt Up Walls

Tabla 4. Coefficients of Friction for Shaar-FrictionConnection Design [Reproduced fromReference 4]

RecommendedcoefficientCrackinterface of friction,p

Concreteplacedmonolithically 1.4A

Concreteplacedagainsthardenedconcretewithsurfaceintentionally 1.Oxroughened

Concreteanchoredtoas-rolledstructuralsteelbyheadedstudsor 0.7Xreinforcingbars

Concreteplacedagainsthardenedconcretenotintentionallyroughened 0.6X

X= 1,0for n.rrnal. weight concrete, 0,85 for %and-4ghtweighV’ concrete,and 0.75 for all-lightweight concrete.

Table 5. Deei n Shear Strength of Single-?ecfStuda

leslgn shear strength, 4W.,ted by concrete strength,, Hps

Hei

Iin

Edgedistance, d.,

in.

2345678

29

Stud diameter, d,,

1111

v, % V, %

1.2 1.2 1.2 1.21.8 2.6 ~:; 2.61.8 4.f 4.71.8 4,1 7.3 7,31,6 4,1 7.3 10,51,8 4,1 7.3 11.41,8 4.’ 7.3 11,41,8 4,1 7.3 11.4

in.

T

3/4 7/8

1.2 1,22,8 2,84,7 47?.3 73

10.5 10,514.3 14,316.5 18,716.5 22,4

I Values in shaded area are controlledby edge distance

In the unshaded area ).= 1.0; for othervalues of L multiply tabulated results by L

Design shear strength limited by steel strength, -, kips

““dd%’er’ I /4 I % I v, I 5/, I v,I 7,8“.W. (shearfriction) 2.3/I 5.lp 9.op 14.1/( 20,3JJ 27,6P

w,,, 2.2 5.0 8,8 13,8 19.9 27,1

. f: = 3000 si; for other values of f;, multiply tabulated results by@&&

d.< Iod, then OV.. = @2.d# I/Zd. z 10d. then OV.. = c0800AJfl

. . f. = rjo,fIorI psi; for other strengths multiply by fJ60,000t,= 0.91.= 54,000 Psi

Metric equivalent% 1 i.. = 25.4 mm, 1 Mp = 4.45 kN, 1 psi= 6.89 kPa

concrete strength. The equations from Reference 28are as follows

Edge effects are not considered when

d<.> 10d~ Eq. 3

Shear capacity when a headed stud is not near a freeedge (d, z 10d,,):

@VnC=Q1800A,,k~ Eq, 4where 0 = 0,85

k = Correction factor found in footnote,Table 4

Fig. 14. Shear loading on a stud naar a frea adga. (Rapro-ducad from Reference 1)

Shear capacity when a headed stud is located near afree edge (d, s 10d~),as shown in Fig. 14:

IDVnC= @2xd~fl. Eq, 5

Eq. 5 was developed for normal-weight concrete,Currently no experimental data are available for studslocated near a free edge embedded in lightweight con-cretej therefore, there is no k in Eq. 5, It should bemodified when used for lightweight concretes.

It should be noted that Eqs. 4 and 5 are empiricaland that the length of the stud is not included. If theseequations are used to determine an allowable shearforce, it is recommended that the length of the stud beat least 70°h of that required for full-tension develop-ment. If the length of the stud is less than this, theallowable shear force should be reduced.

In no case should the shear capacity of the connec-tion exceed the shear capacity of the studs. Designshear strength governed by steel strength as suggestedin Reference 3 is

@Vn~= @0,75A,,f Eq. 6where O= 1,0

Eq, 6 was used to calculate the values in Table 5 thatare governed by steel strength,

Note that the values determined by Eq. 6 (designshear strength determined by steel strength) are greaterthan those determined by Eq. 4 (design shear strengthlimited by concrete strength) in Table 5 for a concretestrength of3000 psi. Ifductility of theconnection isamajor consideration, it is recommended that a con-crete strength greater than 3500 psi be used or confine-ment reinforcement that will intersect the assumedfailure cones in the concrete be specified.

TENSION

This section covers tension design of headed studsfollowing recommendations offered in Reference 1andconsidering information presented in References 1, 2,3, 28, and 29, Designs involving combincd shear andtension are discussed in the section “Combined Shearand Tension.”

17

Page 23: Connections for Tilt Up Walls

Table6. Deaign Tensile Strength of Singla-HesdedStuds*

Designtensilestrerar

Edgedistance,d.

2.0

3,0

4.0

5.0

6,0

7.0

>8.0

.f; =3000 psi; forotherstren!X= 1.0 for normal-weight co

other values 011.from Tz

:h, OP.., Iiedge dist:

Studength, &

2,54.05.08,07.08.0

2.54.05.06.07.06.0

2.54,05.06,07,06,0

2,54,05,06.07.08.0

2.54.05.06.07.06.0

2,54.05,06,07,08.0

2,54.05.06.07.08.0

smulbplytret% for Ott04.

ted bw, ki

St!

V2

3.55.36.47,66.69.9

4,47.99.7

11.413.214.9

4.4I0.512.915,217,619.9

4,410.516,119.0?1,9?4,9

4,4I0.516.1?2.6?6.3?9.8

4.4I0.516.1?2,630.734.6

4,410.516,122,630.739.6

~weig

concrete strengthQ

I-hea(

%

3.65,66,77,99,1

10.2

4,66.3

10.111,813,615.4

4.811.113,515.616.120.5

4.611.116,819.722,725.6

4,611,116,623,727.230.7

4.611,116.623.731.735.8

4,611,116.623.731.741,0

Em

4.15.97.06.29.4

10.5

5,16.8

10,512,314.015,6

5,111.714.016.418,721,1

5,111,717.620,523.426.3

5,111,717,624.626,131.6

5,111,717.624,632.636.9

5.111.717.624.632.642.1

n.~

4,56.37.58,69.6

11.0

5.79.4

11.212,914.716.5

5.712,614,917,319.621.9

5.712.618.621.624,527.4

5.712,61S,625,929,432.9

5.712.616.625.934.338,4

5.712.616.625.934,343.9

s multiply tabulated values by

Design tensile strength, QP.,,limited by steel strength, klps

Stud di6meter, d,, in. V, W V, 5A % 7/8

*P., 2.7 6,0 ] 10.6 I 16.6 I 23.9 I 32.5

f, = 60,000 psi; for other steel strengths mulbply by f./60 ,000f, = 0.91,= 54,000 W01=1.o

Metric equivalents 1 in. = 25.4 mm, 1 Mp = 4.45 kN,1 pd = 6.89 kPa

The tension failure surface for headed studs tends tobe conical in shape. For stud groups, the surface isshaped like a truncated pyramid. The angle of thefailure surtace with respect to the concrete surface foranalysis purposes is generally assumed to be 45 de-grees, The tensile strength of headed-stud embedmentswith @0.85 and k from the footnote of Table 4 is

OP.. = ok[&.4f+ LA,] Eq. 7

Reference 28 suggests a tensile-stress level of 4~for the base area and (4/ ~) @l for the sloping sidesof the failure surfaces.

DesignTensileStrengthof Single-HeadedStuds (Teble 6)

Tensile strength of a headed stud embedded as shownin Fig. 8 and located far from a free edge can bedetermined by substituting in Eq. 7 the tensile-stresslevels and stud configuration. The new equation todetermine strength, limited by concrete strength is

CDPnC= @12,61.k(f, + dJ@; Eq, 8

To account for the effect for studs located near a freeedge (d, s 1,), as shown in Fig. 14, Eq. 8 with thestrength reduction factor becomes

@Pn,= cD12.6J?,.L(Q,+ d/J @:C,, Eq. 9

where C,~=d,/Pc5 1

The design tensile strength governed by steel strengthaspresented in Reference I, for@= l.O, is

@Pn.= 13A& Eq. 10

Table 6 shows the design tensile strength based onconcrete strength, edge distance, and steel strengthconsiderations. The lowest applicable value from thistable is the design tensile strength.

Stud Groups(Tables 7 through 11)

A group of studs is designed differently than a singlestud if the shear cones intersect, To account for this, atruncated pyramid is assumed as the failure plane.Design data for groups of headed studs are listed inTables 7 through 11{1.2s1The equations used to developthe values are provided with the appropriate table.

Typical stud and head diameters, in.

Stud diameter, do, in. V, % 1/2 % 3/4 7/8

Stud-head diameter, d,, in. V, 3/4 1 1M 1v, 1%

18

Page 24: Connections for Tilt Up Walls

Table 7. Deeign Tensile Strength of a Stud Group—Away from a Free Edge,,, .~., .

.-” \ ‘... >,.- . .

,.-” . .,., ,)

,.,W.. : fiy m XY + (4/ @ W(2 v’2~a(x + Y + M))]

%. ..’7{ a

11%

,.- -.. ,,‘:.. ,., /. Values shown are for normal-weight concrete with f: = 3000 si;..:.

h. .:: ,..;; -. for other values of k and f:, mulOply tabulated results by X f./ O

/’ - -’Spacing of studs must not exceed 21.

.>’”’ “’:?

,

&J.

2.5

4.0

6.0

8.0

10.0

12.0

Dimensl,y, in.

o2466

1012

02468

1012

02468

1012

02468

1012

02468

1012

02468

1012

]uivalents

Design tensile strel

14

8111518212528

17222631354044

35414753596571

596774818996

104

8998

107116125134143

125135146158166177187

mm,

stud group, kps

19

Page 25: Connections for Tilt Up Walls

Table 8. Deeign Teneile Strength of a Stud Group—Near a Free Edge on One Side

,.?./, ; .,,..

1...~... 4JP”0 : SDDQ’Z Xy + (4/ ~) ~( @l.(zx + y + 21.))]

&l

z~, .,+,,. /

,, / Values shown are for normal-weight concrete with f; = 3000 si;‘> “ +for other values of). and f& multiply tabulated results by L f./3OOO

..’ ./,,,/.’,.

>

Spacing of studs must not exceed 21.,.,

&iJ.

2,5

4,0

8.0

8.0

10.0

12.0

DimensionE in.

o2468

1012

02468

1012

02466

1012

02A

68

1012

026

68

1012

02d

68

1012

Metric equivalents 1 i,

Design tensile strc stud group, kips

24

24344454647483

z5262738393

I04

F788900

Ill2234

507

:435466

G3951647789!02

G7487!01!14!41!41

Page 26: Connections for Tilt Up Walls

Table 9. Design Tensile Strength of a Stud Group—Near a Frea Edge on Two Oppoeite Sidea

\

\

-\//” ‘,,. ‘,,,.-’

l!aJP”c : m: W Xy + (4/ ~) ff:(z @l.x)]

%

,.. ‘\ @,., .,> >’,

Values shown are for normal-weight concrete with f; = 3000 psi:,’; ‘,,”/

1. ‘,, ,.-

2

for other values of A and f:, multiply tabulated results by k -..’ “,.- ,. Spacing of studs must not exceed 2P,

‘, ,, ,,,’,. ”,,

‘k-$

%

/.’..+ ,,’

..4/, .

1., in.

2,5

4,0

6.0

8.0

10.0

i 2.0

Metric

~mensiony, in.

o2466

1012

02468

1012

02468

1012

02468

1012

02468

1012

02466

1012

uivalents: 1

Design tensile stre

2

;34456

2345567

4556788

567889

10

7669

101111

89

10fl111213

.25

4 6 8

3 5 75 7 106 10 136 12 169 14 19

11 16 2212 18 25

5 6 117 11 148 13 17

10 15 2011 17 2313 20 2614 22 29

8 13 1710 15 2011 17 2313 20 2614 22 2916 24 3217 26 35

11 17 2313 20 2614 22 2916 24 3217 26 3519 29 38

i

20 31 41

14 22 2916 24 3217 26 3519 29 3620 31 4122 33 4423 35 47

17 26 3519 29 3820 31 4122 33 4423 35 4725 37 5026 40 53

Im, 1 MP= 4.45 kN

I

10

913

J242731

14162226293337

22262933374044

29333740444852

37404448525559

44465255596367

stud group, kips

21

Page 27: Connections for Tilt Up Walls

Table 10. Design Teneile Strength of a Stud Group—Nasr Free Edges on Two Adjacent Sides

,,. p,..- , X\.

,.- , ~,//” to---v ..,.,,/ ,11

L 1, ..< ‘.

\\ /,

,U,,.

<

. . . ,,..’$... ..Q ‘“”

&,iiJ.

2.5

4.0

6,0

8.0

10,0

12,0

Metric

lmensioy, in.

o2468

1012

0246

1:12

02468

1012

02468

1012

02468

1012

02468

1012

N.alents 1

Design tensile stre

2

23578

1012

466

11131517

6111417202326

14182226293337

2226

?54044

I

49

31364146525762

25,4

4

357

10121517

58

1114

;23

11141822262933

J2631354044

-z-313641465257

35414753596571

m

oPfl. : CDDgW Xy + (4/ V’2) V’?z( V’21e(x + y + P.))]@

Values shown are for normal-weight concrete with f;= 3000 psi;for other values of X and f:, multiply tabulated results by ?.-

Spacing of studs must not exceed 21.

I stud group, kips

Fii

E41518171

G314~52627363

G445587706900

z597163950719

%

:01132639

G930720344760

22

Page 28: Connections for Tilt Up Walls

Table 11. Deeign Teneile Strength of a Stud Group—Near Three Adjacent Free Edges

\

yl,.-’ &. . ~~~~

Values shown are for normal-weight concrete with f; = 3000 si;

!6 ‘,,,

hfor other values of k and i;,multiply tabulated results by k f./3OO

,,.,’ \ Spacing of studs mwt not exceed 21.

$:’.; “’’;;’’””* ~<>.

Q

2.5

4.0

6.0

6.0

10.0

12.0

Metrl,

DtmenslM in.

o2468

1012

02468

totz

o2468

1012

02468

1012

02468

1012

02468

10tz

quivalents

Design tensile strength, cDP.., of a stud group, NPS

c

123345

1223455

223A

s567

3455876

4556788

14

134679

10

24578

1011

T578

101113

578

10It1314

76

1011131416

6101113141617

=25.4 mm,

76257:9’

111316

468

11131517

68

1113151720

8111315172022

111315

z2224

1315

G222426

,=4

I x. in.

Page 29: Connections for Tilt Up Walls

- Punchingshear

Tension Tension and moment

Fig. 15 Stud groups in thin sections under combined ten-sion and moment. (Reproduced from Reference 1)

STUDGROUPSIN THIN SECTIONS

Where plates are anchored to the face of a wall panel,special consideration should be given to stud groups.Since tilt-up panels generally have thin sections, pull-out of the anchor plate may produce a localized orglobal failure. As illustrated in Fig. 15, anchor platessubjected to tension or bending result in two generalfailure modes. Under tension, the stud group has atypical pullout failure with the shear boundary shapedsimilar to a truncated pyramid. When the anchor plateresists a force couple, with compression on one sideand tension on the other, the tension face “pulls out”while the compression zone “punches through?

Special consideration and design procedures mustbe used to accommodate either of the above situations.For guidance in design see Reference 28.

COMBINEDSHEARAND TENSION

Interaction of shear and tension on studs will result instrength reduction under combined loading condi-tions. The following interaction equations should beused to evaluate strength reduction of both concreteand steel:

Concrete

Steeh

i(i)’+(fc)’k1 Eq.11

Plate thickness for stud groups subjected to com-bined shear and tension should not be less than ?3 thediameter of the studs.

STEEL DESIGN

Design of light steel framing and steel connection ele-ments is beyond the scope of this text. For furtherinformation on steel design, refer to Reference 20, theAISC Manual ofSteel Construction.

WOOD DESIGN

Design of wood joints and support elements is beyondthe scope of this text. For further information on wooddesign, see Reference 27, the NFPA National DesignSpecl$cation for Wood Construction.

24

Page 30: Connections for Tilt Up Walls

Connection Details

In this section connection details are provided that are satisfactorily or prove economical in a given area. Eachconsidered typical. They have been obtained from detail should be studied thoroughly before adopting itssources in various areas of the United States and Can- use. A brief commentary describing each connectionada. Due to local environmental conditions such as followed by a list of advantages and disadvantages istemperature, humidity, expansive soils, or seismic con- provided, Tbe details are divided into five categoriessiderations or because of locally accepted details and Wall panels to foundation, floor, roof, wall panel, andpractices, some of the details shown may not perform steel column connections,

WALLPANELTO FOUNDATIONCONNECTIONS

Trenched Footing/WallConnection

In this connection, the top elevation of the continuousfooting is raised to allow direct support of the slab-on-grade. The edge of the slab is used for proper alignmentof the wall panel. Lateral suppnrt at the base is provid-ed by embedded material in wall and floor.

Advantage: Slab-on-gradefacilitates erection of thewall,

Disadvantage Forming of the slab-on-grade requirestight tolerances.

Restraints: Primary F,, F3Secondary: F*

Footing/WallConnectionwith ExteriorDowels

In this connection, the wall panel is grouted onto acontinuous footing, isolated footings, or drilled pier.Drilled-in dowels are provided on one or both sides ofthe wall panel. The dowels are used for proper align-ment of the wall panel during erection. Leveling shimsare placed at each end of the panel. The panel isconnected to the slab on grade with dowels or embed-ments (see Connection Detail for “Slab on Grade/WallConnection;’)

Advantage: Use of the dowel facilitates erection nfthe wall.

Restraints: Primary F,, Fs

25

Page 31: Connections for Tilt Up Walls

WALLPANELTO FLOORCONNECTIONS

Slab on Grade/Wall Connection

In this connection, the floor slab provides lateral sup-port for a wall panel. The slab on grade is cast, exceptfor a narrow strip (2 to 4 ft wide) adjacent to the wallpanel. The wall panel has cast-in-place bent dowels.Threaded inserts can be used in place of bent bars,Dowels or bars are used to form splice with reinforce-ment in floor slab. Floor area adjacent to the wall panelis then cast. Control joints in closure strips shouldmatch control joints in floor,

Advantages:

Disadvantage

Fabrication is simpleConnection is self-forming,

Dowels may be damaged during han-dling.

Primarw F,Second&:’Fl, Fz

s,Nole:

Wall f.undoti, n

k

F,not shown

F,

Precast DoubleTee/Wall ConnectionwithLedge

In this connection, a concrete ledge is cast monolithi-cally with a wall panel, The ledge provides verticalsupport for a double-tee floor system. The double-teebeams rest on bearing pads. The double-tee floor sys-tem is topped with a thin layer of reinforced concrete,Deformed dowels in the wall extend into the reinforcedconcrete topping to provide lateral support for the wallpanel. Steel embedments or threaded inserts may beused in place of bent bars,

Advantages: Minimal number of components inconnection.Connection is self-forming.

Disadvantages: Casting of ledge complicates fabrica-tion of wall panel.Special steps are required to protectdowels during handling,Placing of the double tee units underthe dowels may complicate erection.

Restraints: Primary FI, F3Secondary F2

26

Page 32: Connections for Tilt Up Walls

Wood Joist/WallConnectionwith JoistHanger on Wood Ledger

In this connection, a composite ledger provides verti-cal support for wood joists. The ledger includes a woodnailer bolted to a continuous steel angle using counter-sunk nuts. The continuous steel angle is welded to steelembedments located at selected intervals. Each joist isconnected to the ledger through a steel hanger. Eachsteel hanger is nailed to the top face of the ledger. Theplywood flooring sheets are nailed to the ledger andthe wood joist to provide lateral support for the wallpanel.

Advantage

Dkadvantages:

Embedment ulates allow large con-struction tolerances.

Fabrication of the composite ledgerrequires additional effort.Welding in the up-hand position maybe required.Consolidation of concrete nearembedment plate may be difficult.

Primary: F,, F3Secondary F1

HeavyTimber Beam/Wall ConnectionwithSteel Shoe

In this connection, a steel shoe, welded to a steelembedment, provides vertical support for the heavytimber beam. The beam and the roof diaphragm pro-vide lateral support for the wall panel. Wood joists aresecured to the wall panel through embedded steel strapsin Seismic Zones 2, 3, and 4.

Advantages Fabrication and erection are simple.Steel embedment allows large con-struction tolerances.

Disadvantages: Bearing-type bolted connection re-quires tight tolerances.Consolidation of concrete aroundembedment may be difficult.Exposed steel may require fireproof-ing.

Restraints Primary F,, F,Secondary: FZ

27

Page 33: Connections for Tilt Up Walls

WALL PANELTO ROOFCONNECTIONS

PrecastDoubleTee Roof/PrecastBeam/WallConnections

In this connection, a precast concrete beam spansbetween adjacent reinforced concrete columns, Thebeam provides vertical support for a double-tee roofsystem. The precast concrete beam also provides lat-eral support for the wall panel. One end of the double-tee beam rests on a flexible bearing pad that accom-modates movement due to volume change while theOPPOsiteend-bearing is rigid. The double-tee flange iscantdevered at the end so that the flange extends overthe wall panel. Clip angles are used at selected intervalsto tie the wall panel to the beam. Each angle is weldedto a steel embedment cast into the beam. Each angle isbolted to the wall panel through embedded threadedparts. Oversized holes are used in the angles to accom-modate movement due to the volume change anddeflection of the beam,

An alternate supporting detail for the precast doubletee is shown as Connection Detail for “Precast DoubleTee/Wall Connection with Ledge,”

Advantages: Erection is simple.The connection accommodatesmovement due to volume change.

Disadvantage Exposed steel angles may require fire-proofing.The welder must work in the up-handposition.Placing of cast-in-place inserts re-quires tight tolerances.

Restraints: Double Tee/Precast Concrete BeamPrimary F,

Precast Beam/WallPrimary F3

PrecastDoubleTee Roof/Wall Connections

In this connection, the edge beam of a double-tee roofsystem provides lateral support for a wall panel. Clipangles are used at selected intervals to tie the wallpanel to the edge beam, Each angle is welded to a steelembedment cast into the edge beam. Each angle isbolted to the wall panel through embedded threadedparts. Oversize holes are used in the angles to accom-modate movement due to volume change and deflec-tion of the edge beam. Vertical support for tbe ronfshould be provided through a separate system, such asthe one shown in Connecting Detail for “Precast Dou-ble TeeRoof/Precast Beam/Wall Connections.”

Advantages

Dkdvantagex

Restraint

Fabrication and erection are simple,The connection accommodatesmovement due to volume change anddeflection of the edge beam.

Exposed steel angles may require fire-proofing,The welder must work in the up-handposition,Placing of cast-in-place inserts re-quires tight tolerances.

Primary F,

Page 34: Connections for Tilt Up Walls

PrecaatDoubleTee Roof/Bearingon WallConnection

In this connection, the double-tee roof system is sup-ported directly by the tilt-up wall panels. Steel embed-ments are cast into the underside of the stems of thedouble tees and into the top edge of the wall panels, Apivot bar is welded between the bearing plates in thetee stems and the wall panel. The double-tee roofprovides lateral support at the top of the wall panels.

Advantages Erection is simple,Minimal number of components.Embedments allow large constructiontolerances.

Disadvantages: The connection accommodates onlyminimal displacement or rotation dueto volume changes or deflections inthe double tee,Exposed steel may require fireproof-ing and weather protection,The welder must work in the up-handposition.Special reinforcement may be re-quired in the wall panels at bearingpoints.

Restraints: Primary F,, F3

Precaat Hollow-CoreRoof/Bearingon WallConnection

In this connection, a recessed ledge in the tilt-up wallprovides vertical support for a precast hollow-core roofsystem. The hollow-core units rest on a flexible bearingpad that accommodates movement due to volumechange. Clip angles similar to those shown in Connec-tion Detail for “Precast Double TeeRoof/Precast Beam/Wall Connections” may be needed to provide lateralsupport to panels,

Advantages

Disadvantage:

Restraints:

Erection is simple.Connection accommodates move-ment due to volume change,

Special reinforcement and formingmay be required at the ledge,

Primary Fl, F3

29

Page 35: Connections for Tilt Up Walls

In this connection, a reinforced concrete pilaster pro-vides vertical support for a steel girder, The pilaster iscast on the tilt-up panel while in the horizontal posi-tion. The pilaster is reinforced as a column with tiesprojecting from the panel. This connection is usedwhen concentrated roof or floor lnads are large andcannnt be efficientlytransmitted through the wall panel.The vertical load is transmitted through bearing on thesteel angle. The steel angle is connected to the pilasterwith embedments. Slotted holes areusedin the girderto accommodate construction tolerances. The pilasterand the roof diaphragm provide lateral support for thewall panel. Embedded reinforcing bars are extendedfrom the wall panel into the pilaster and welded to thesteel angle for anchnrage. For comments on the contin-uous angle, refer to Connection Detail for “In-PlaneWall/Wall Connection with Continuous Steel Chord:’

Advantage Suitable for supporting large, concen-trated loads.

Dkadvantagew Fabrication of the pilaster and itsfoundation requires additional effortat the jobsite.Exposed steel may require fireproof-ing.

Restraint* Steel Girder/PilasterPrimary: F1Secondary F3

Pilaster/WallPrimary F3Secondary F!, F2

St&iirder/Wall Connectionwith Recessed

In this connection, a recessed pocket in the wall panelprovides vertical support for a steel girder. The load istransmitted through bearing on an embedded steelangle. Reinforcing bars are welded to the steel anglefor anchorage. The steel girder and the concrete roofdiaphragm provide lateral support for the wall panel,The steel girder is bolted to the wall panel throughembedded threaded parts. Slotted holes are used in thegirder to accommodate construction tolerances. Thisdetail can also be applied to a steel joist/wall connec-tion. Forcomments onthecontinuous angle, refer toConnection Detail for “In-Plane Wall/Wall Connec-tion with Continuous Steel Chord.”

Advantage

Disadvantages

Restraints

Number of components in connectionis minimal.

Forming of the recessed pocket andembedment of the angle require tighttolerances,Consolidation of concrete near thepocket may be difficult.Exposed steel may require fireproof-ing,Placing the end of the girder withinthe recessed pocket may complicateerection procedures.

Prima~ Fl, F3Secondary F2

_——

30

Page 36: Connections for Tilt Up Walls

Steel Girder/ClipAngle Wall Connection

In this connection, vertical support for a steel girder isprovided by a clip angle attached to the wall panel bythreaded inserts. An alternate for attachment is to weldthe clip angle to an embedded plate, The clip angle isthen welded to the web of the beam, An alternateconnection of beam to clip angle is bolting. The clipangle has slotted holes to allow in-plane movement ofthepanels andaccommodate large construction toler-ances. It is preferable to locate beam or girder supportsaway from joints between panels. A minimum of2ftis suggested.

Advantages:

Disadvantages:

Restraints:

is minimal,Slotted holes (orembedments) allowlarge construction tolerances,

Exposed steel may reauire firem’oof-ing.Welding of beam to clip angle must bedone in overhead position,

Primarx F,Second&y: “Fz,F,

Steel Joist/Wall Connectionwith Seat Angle

In this connection, a seat angle provides vertical sup-port for a steel joist. The seat angle is welded to a steelembedment after the panel is cast. Alternatively abuilt-up steel-plate bracket can replace the seat angle.The steel joist is welded or bolted to the seat angle.The steel joist and roof diaphragm provide lateralsupport for the wall panel, For comments on the con-tinuous angle, refer to Connection Detail for “In-PlaneWall/Wall Connection with Continuous Steel Chord?’

Advantages Erection is simple,Steel embedment allows large con-struction tolerances,

Disadvantages: Exposed steel may require fireproof-ing.Consolidation of concrete near steelembedment may be difficult.

Restraint Primary FI, F3Secondary F2

31

Page 37: Connections for Tilt Up Walls

Metal Deck/Wall Connection

In this connection, a continuous steel angle providesvertical support for a corrugated metal roof deck andcan be used as the chord for the roof diaphragm. Theroof deck is tack or puddle welded to the angle, Theangle is bolted to the wall through embedded threadedparts. Alternatively, the steel angle can be welded tosteel embedments at selected intervals. The roof dia-phragm provides lateral support for the wall panel, Foradditional comments on continuous angle refer toConnection Detail for “In-Plane Wall/Wall Connec-tion with Continuous Steel Chord.”

Advantage

Disadvantages:

Restraints:

Fabrication and erection are simple.

Installation of the continuous anglemay require tight tolerances,Exposed steel may require fireproof-ing.

Primary F,, F3

Wood Joist/WallConnectionwith WoodLedger

In this connection, a wend ledger provides verticalsupport for a wood-joist roof system. The ledger isconnected to the wall panel using embedded threadedparts, The embedments can be cast in the concrete byusing the predrilled ledger as a template. Embeddedsteel straps are nailed to wood joists to provide lateralsupport for the wall panel in Seismic Zones 2, 3?and4, Bearing between the wall panel and the wood Joistsprovides lateral support when an inward horizontalforce is applied

Advantage:

Disadvantage

Fabrication and erection are simple.

Close placement tolerances are re-quired on cast-in-place steel straps,

Primary F,, F3Seconda~ F2

Secondary F*

32

Page 38: Connections for Tilt Up Walls

Wood Joist/Wall Connectionwith JoistHangeron Wood Ledger

In this connection, a wood ledger provides verticalsupport for wood joists. Each joist is connected to theledger through a steel hanger. Each steel hanger isnailed to top face of the ledger. The ledger is connectedto the wall panel through embedded threaded parts.The embedments can be cast in the concrete by usingthe predrilled ledger as a template. An alternate attach-ment for the wood-ledger connection to the wall panelis shown in Connection Detail for “Wood Joist/WallConnection with Joist Hanger on Wood Ledger.” Theplywood roof sheets are nailed to the ledger and thewood joists to provide lateral support for the wallpanel. Embedded steel-strap ties are required in Seis-mic Zones 2, 3, and 4, as shown in Connection Detailfor” Wood Joist/Wall Connection with Wood Ledger:

Advantage Fabrication and erectinn are simple.

Restraints: Primary F,, FzSecondary Fz

Wood Joist/Wall Connectionwith JoistHangeron PanelTop

In this connection, the top of a wall panel providesvertical support for the wood joists. Each joist is con-nected to top of the wall panel through a steel hanger.Each hanger is nailed to a wood nailer. The woodnailer is bolted to the top of the wall panel usingembedded threaded parts with countersunk heads. Thewood nailer can be utilized as part of the formwork forcasting the wall panel, as a template for the embed-ments. The plywood roof sheets are nailed to the woodnailer and the wood joists to provide lateral supportfor the wall panel.

Advantage Fabrication and erectinn are simple.

Restraints: Primary: F,, FsSecondary Fz

L“““””o II ...

,. / ,,#k

F,

F,

1-..

33

Page 39: Connections for Tilt Up Walls

PlywoodRoofDeck/Wall ConnectionwithWood Ledger on Panel Top

In this connection, the top of a wall panel providesvertical support for a narrow strip of the roof adjacentto the wall panel. The wood joists span parallel to thewall panel. The plywood sheets are nailed to a woodnailer. The wood nailer is bolted to the top face of thewall panel using embedded threaded parts with coun-tersunk heads. The wood nailer can be efficiently uti-lized as part of the formwork for casting the wall panel.The plywood sheets provide lateral support for thewall panel.

Advantage: Fabrication and erection are simple.

Restraints: Primary F,, F3Secondary F2

WALL PANELTO WALL PANELCONNECTIONS

In-PlaneWall/Wall Connectionwith SteelEmbedment

In this connection, steel angles are embedded at theinterior face of the wall panels. A steel plate is weldedto both embedments to form the connection. It isrecommended that no more than two or three panelsbe connected without a free joint. This detail can alsobe used with a recessed pocket and then plastered foresthetics.

Advantage.x Number of components in connectionis minimal.Fabrication and erection are simple.Steel embedments allow large con-struction tolerances,

Disadvantage% Exposed steel may require fireproof-ing.Consolidation of concrete near steelembedments may be difficult,Very rigid connection, can cause localdistress due to volume changes.

Restraints: Primary F,, F2Seconda~ F3

/--’2

34

Page 40: Connections for Tilt Up Walls

In-PlaneWall/Wall ConnectionswithThreaded Ineerts

In this connection, threaded inserts are embedded atthe interior face of the wall panels. A steel plate isbolted to both panels. One of the bolt holes in theconnection plate is slotted to allow movement due tovolume change and to make alignment easier.

Adva~tagex Fabrication and erection are simple.Slotted holes allow movement due tovolume change.

Dkadvantages: Exposed steel mayrequire fu’eproof-ing.Consolidation of concrete near steelembedments may be difficult.

Restraint.% Primary Fz

In-PlaneWall/Wall Connectionswith SlittedPipe

In this connection, two adjacent wall panels are con-nected thrnugh slitted pipes. Each pipe includes onelongitudinal slit. At either side of the slit, the pipe iswelded toembedmentstofnrm acnnnection. Gener-ally the pipe is placed into a recessed pocket. Aftererection, a bond-breaking agent is applied on the pipeand the recessed pocket is grouted for esthetics.

Advantages: Connection accommodates some hor-izontal differential movement be-tween wall panels.Connection can be “hidden.”

Disadvantages Consolidating of concrete near steelembedments may be difficult.Pocket complicates fabrication of wallpanel.Welding of pipe maybe difficult.

Restraints Primary FI, F3

/--’2 w,‘,

sectionfib

35

Page 41: Connections for Tilt Up Walls

CornerWall/Wall Connectionswith SteelEmbedments

In this connection, wall panels are connected throughclip angles. Each clip angle is welded to steel embed-ments cast into the wall panels. Alternatively the clipangles can be bolted to the wall panels through embed-ded threaded parts. Rigid, welded corner connection isless critical than Connecting Detail for “In-Plane Wall/Wall Connection with Steel Embedments” for distressdue to volume change.

Advmstagew Number of components in connectionis minimal.Fabricating and erection are simple.Steel embedments allow large con-struction tolerances.

Disadvantage% Exposed steel may require fireproof-ing.Consolidation of concrete nearembedment may be difficult.Connection may require welding inthe up-hand position.

Restraints: Primary F,, Fz, Fs

CornerWall/Wall Connectionswith ThreadedInserts-Type 1

In this connection, wall panels are connected throughclip angles. The clip angles are bolted to the panelswith threaded inserts cast into the panels.

& ..w.2”

,<:

Number of components in connectionis minimal.Fabrication and erection are simple.

Exposed steel may require fireproof-ing,Clnse construction tolerances re-quired.

Primary FA F3

---

\

--J

F,

36

Page 42: Connections for Tilt Up Walls

In-PlaneWall/Wall ConnectionswithContinuousSteel Chord

In this connection, a continuous angle is embedded inthe surface with headed studs anchoring the steel sec-tion over one quarter of the panel length centered onthe centerline of the panel. In the remaining threequarters of the panel width the chord is bolted to thepanel through slotted holes. At each joint, a steel plateis welded to the angles attached to the adjacent panelsto focm the connection. The continuous steel sectionmay provide vertical support for a portion of a roof orfloor system and also act as chord for the roof dia-phragm.

Advmrtagex

Disadvantages:

Restraints:

Fabrication and erection are simple.Steel embedments allow large con-struction tolerances.

Exposed steel may require fireproof-ing.Connection may require welding inthe up-hand position.Consolidation of concrete nearembedment may be difficult.

Primary F,, FzSecondary Fs

In-Plane DiaphragmChordWall/WallConnection

In this connection, wall panels are connected continu-ously by means of continuous reinforcement. Reirr-forcement is mechanically anchored to the center one-third of the panel. The outer one-third of the top chordof reinforcement is unbended by encasement in card-board or plastic sleeves. A recessed pocket is providedto allow weldment of an angle to reinforcement inadjacent wall panels, thus forming the continuouschord. This detail is commonly used with wood roofsystems.

Advantages: Erection is simple.Accommodates movement due to vol-ume change.

Disadvantages: Additional material and labor costs informing recessed pocket and formingunbended length of reinforcement.Welding in up-hand positinn.

Restraint Primary: FI

7‘,

37

Page 43: Connections for Tilt Up Walls

WALL PANELTO STEEL COLUMNCONNECTIONS

Steel Column/WellConnectionwith BoltedSteel Anglee

In this connection, each wall panel is connected to asteel column through bolted steel angles. Each steelangle bears against the interior face of a column flangeand is bolted to the wall panel through embeddedthreaded parts.

Advantages Fabrication and erection is simple.Connection accommodates move-ment due to volume change.Large tolerances can be specified.

Dkadvantages Special steps may be required to pro-tect exposed threaded parts duringhandling.Exposed steel may require fireproof-ing.

Restraink Primary: F,

Wall/Steel Column/WallConnectionwithBoltedSteel Anglee

In this connection, the steel column to wall ConnectionDetail “Wall Panel to Steel Column Connections” isapplied to corner wall panels adjacent to a steel col-umn.

Advantages Fabrication and erection is simple.Connection accommodates move-ment due to volume change,Large tolerances can be specified.

Disadvantages: Special steps may be required to pro-tect exposed threaded parts duringhandling,Exposed steel may require fireproof-ing,

Restraints Primary: F2, F3

-=4

.

----?,

t

/F3

38

Page 44: Connections for Tilt Up Walls

References

1. PCI Manual on Detign of Connections for Precast,Prestressed Concrete, 2nd cd., to be published,

2. Martin, L. D., and Korkosz, W.J., ConneclicmsforPrecast Prestressed Concrete Buildings IncludingEarthquake Resistance, Prestressed Concrete In-stitute, 1982.

3. PCI Design Handbook for Precast, PrestressedConcrete, 3rd cd., Prestressed Concrete Institute,Chicago, 1985.

4, ACI Committee 318,Building Code Requirementsfor Reinforced Concrete, American Concrete Insti-tute, Detroit, 1983.

5. Clark, C. A., “Development of Tilt-Up Construc-tion,” Journal of the American Concrete Institule,vol. 44, no, 9, May 1948,

6. Aiken, R., “Monolithic Concrete Wall Building—Methods, Construction, and Cost,” Proceedings ofthe American Concrete Institute, vol. 5, 1909, pp.83-105, reprinted in Concrete-International De-sign & Construction, vol. 2, no. 4, April 1980.

7. Collins, E T., Ti/t-Up Estimating and Drafting,“Know How” Booklet, Know How Publication,San Gabriel, 1953.

8. Collins, E T., Tilt-Up Design, “Know How” Book-let, Know How Publication, San Gabriel, 1954.

9. Collins, E T., Till-Up Equipment and Construc-tion, “Know How” Booklet, Knnw How Publica-tion, San Gabriel, 1954.

10. Collins, E T., Building with Tilt-Up Know HowConstruction, 2nd cd., Krrow How Publication,San Gabriel, 1958.

11. DeCourcy, J. W,,“Structural Joints,” Concrete andConstructional Engineering, vol. LVHI, no. 5,Londnn, May 1963,

12. Escedi, T. J., “Connections-Conceptual Design;’PCI Seminar, Pre-print Symposium on Planningand Design of a Precast Concrete Bearing Build-ing, Las Vegas,October 1983.

13. Design and Control of Concrete Mixtures, EBOOIT,Portland Cement Association, 12th cd., 1979.

14. Gustaferro, A. H., and Martin, L. f?, PCI Designjtrr Fire Resistance of Precast Prestressed Concrete,Prestressed Concrete Institute, Chicago, 1977.

15. Structural Welding Code-Steel, D 1.1-84,AmericanWelding Society, Inc., Miami, Fla., 1984.

16. Structural Welding Cnde-Reinforcing Steel, D 1.4-79, American Welding Society, Inc., Miami, Fla.,1979.

18. Standard Specification for Structural Steel, ASTMA 36-81a, American Society for Testing and Mate-rials, Philadelphia, 1982.

19, Unified Inch- Screw Threads, ANSI B1.1-1982,American Society of Mechanical Engineers, New

20.

21.

22

23

24

25

26

27.

28.

29.

York, 1982.Manual of Stee/ Construction, 8th cd,, AmericanInstitute of Steel Construction, Chicago, 1980,Standard Specification for High-Strength Bolts forStructural Steel Joints, Including Suitable Nutsand plain Hardened Washers, ASTM A 325.76c,Part 4, American Society for Testing and Mate-rials, Philadelphia, 1982.Standard Specification for Quenched and Tem-pered Alloy Steel Bnlts for Structural Steel Joints,ASTM A 490-76a, Part 4, American Society forTesting and Materials, Philadelphia, 1982.Building Movement and Joints, EB086B, PortlandCement Association, 1982.Standard Specification for Steel Bars, Carbon,Cold-Finished, Standard Quality, ASTM A 108-81,American Society for Testing and Materials, Phil-adelphia, 1982.Standard Specification for Defnrmed and PlainBillet-Steel Bars for Concrete Reinforcement,ASTM A 615-81a, American Society for Testingand Materials, Philadelphia, 1982.Standard Specification for Epoxy-Resin-BaseBonding Systems for Concrete, ASTM C 881-78,American Snciety for Testing and Materials, Phil-adelphia, 1978.National Design Specification for Wood Construc-tion, National Forest Products Association, Wash-ington, 1977.Sbaikh, A. E, and Yi, W., “In-Place Strength nfWelded Headed Studs: PCI Journal, vol. 30, no.2, 1985,pp. 56-81.McMackin, F!J.; Slutter, R. G.; and Fisher, J. W.,“Headed Steel Anchor under Combined Loading,”AISC Engineering Journal, vol. 10, no. 2, 2ndquarter, 1973.

17. Standard Specification for Carbon Steel ExternallyThreaded Standard Fasteners, ASTM A 307-80,Part 4, American Society for Testing and Mate-rials, Philadelphia, 1982.

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Page 45: Connections for Tilt Up Walls

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KEYWORDSbolts,connections,design,details,ductility,durability,embed-ments, grout, inserts, load path, restraint, studs, threaded rods, tilt-up, toler-ances, welding.

ABSTRACT A reference for connections commonly used in tilt-up construc-tion with 28 perspectivedrawingsof details betweenwall panelsand founda-tion, floor,adjacentwallpanels,and roof Detailswereobtainedfrom engineer-ing offices experienced in tilt-up design and from a review of current literature.Connection elements such as standard bolls, high-strength bolts, coil bolts,threaded inserts, expansion inserts, embedments, welding, dowels, groul, andbearing pads are all discussed.

REFERENCE CcmnectiomforTi/t-Up Wa//Cmstruclim (EB 110.01D), Port-

land Cement Association, 1987.

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Page 46: Connections for Tilt Up Walls

IElPORTLAND CEMENT I I ASSOCIATION,“m,anlzattooO(<em.,,,,“,,, ”,,,,”,,,, to ;mp,ove ande,,w,d the “,,s ., p.,,1.nd <em,”, and <oncrefc th,o.gh mark., d,vclop,,,m,t, o,,inm, in,, ,mear<h, ,ducation, and ,ublic ,w,, wc,,k.

5420 Old Orchard Road, Skokie, Illinois 60077-1003

Printed in USA, EB1 10.01 D