Cambodia Bridge Design Standard

8/9/2019 Cambodia Bridge Design Standard

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CAM PW 04-102-99 CAMBODIAN STANDARD

AMENDMENTS TO BASE DOCUMENT BRIDGE DESIGN

July 1999 MINISTRY OF PUBLIC WORKS AND TRANSPORT

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CAMBODIAN STANDARD CAM PW 04-102-99

BRIDGE DESIGN AMENDMENTS TO BASE DOCUMENT

MINISTRY OF PUBLIC WORKS AND TRANSPORT July 1999 Page 1 of 39

FOREWORD

The Cambodia Bridge Design Standard is intended to be used forthe design of all new road and railway bridges in the Kingdom ofCambodia. The Cambodian Bridge Design Standard consists ofthe following complementary documents:

- CAM PW 04-101-99 Australian Bridge Design Code 1996(the Base Document) and associated Commentary;

- CAM PW 04-102-99 this document (the Amendments)

which contains amendments and additions to the Basedocument; and

- The Commentary on the Cambodian Bridge DesignStandard which contains amendments and additions to theCommentary on the Base Document.

These documents shall be considered together. In the case of aconflict between the provisions of the Base Document and theprovisions of the Amendments, the Amendments shall overridethe Base Document.

From time to time the Base Document may be changed by the

Australian Authorities. Any such change shall be automaticallyincorporated into the Cambodian Bridge Design Standard unlessit conflicts with a provision of the Amendments.

For the purpose of regulating and interpreting the provisions ofthis Standard, the AUTHORITY shall be the Cambodian Ministryof Public Works and Transport.


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Page 2 of 39 July 1999 MINISTRY OF PUBLIC WORKS AND TRANSPORT

This document has beenproduced for the Kingdom of

Cambodia as a joint Australia –Cambodia project sponsored bythe Australian Agency forInternational Development(AusAID).

Valuable assistance andoperational advice wasprovided by the staff of theCambodian Ministry of PublicWorks and Transport (MPWT)

Technical research andspecialist input was providedby the Australian consultingfirms of McMillan Britton & KellPty Limited and Willing &Partners Pty Ltd.

Reproduction of extracts from this publication may be made subjectto due acknowledgment of the source.

Although this publication is believed to be correct at the time ofprinting, neither the MPWT nor AusAID accept responsibility for anyconsequences arising from the use of the information contained in it.People using the information should apply, and rely upon, their ownskill and judgement to the particular issue which they areconsidering.


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TABLE OF CONTENTS

PART A LIST OF AMENDED CLAUSES IN THE BASE DOCUMENT..... ........... ........... ..... ............ 5

PART B TEXT OF AMENDED CLAUSES IN THE BASE DOCUMENT

Section 1 General 7

1.1 General Principles ..............................................................................................7

1.1.1 Applicability ....................................................................................7

1.3.1 Bridge Carriageway Widths.................... ........... . ....... ....... ....... ....... ...7

1.3.2 Edge Clearances for Bridges Without Footways .......... ........... ........... .7

1.3.4 Vertical Clearance at Structures............... ........... ...... ............. ........... 7

1.10 Australian Standards .......... ........... .......... . ........... ........... .......... ....... ........ ....... ....8

Section 2 Design Loads

2.3 Traffic Loading.... ........... ........... ...... ........... ........... .......... ........... ........... .......... ....9

2.3.3 L44 Lane Loading ............................................................................9

2.3.4 Heavy Load Platform Loading............... ........... ...... ............ ........... ..... 9

2.3.5 Number of Lanes for Design and Lateral Position of Loads.... .... .... ... .. 11

2.3.5.2 Heavy load platform loading ........... ........... .......... ........... ........... ...... 112.3.8 Fatigue Loading............ ........... ......... .......... ........... ........... ....... ...... 11

2.4.2 Dynamic Load Allowance -T44 Truck and L44 Lane loading ... ... ... ... ...11

2.5.2 Braking forces............................................................................... 11

2.5.4 Minimum Lateral Restraint Capacity - Ultimate Limit State ................ 12

2.8 Wind Loads 13

2.8.1 General.........................................................................................13

2.8.2 Basic design wind speed........... ........... .......... .......... ........... ........... 13

2.8.2.1 Derivation of site design gust wind speed (Vz)...................................13

2.8.2.2 Terrain Category.......... ........... ........... .......... ........... ........... ............ 14

2.8.2.3 Terrain and structure height multiplier (M (z,cat) )..................................15

2.8.2.5 Topographic multiplier (Mt)..............................................................17

2.8.3 Transverse wind load........... ........... .......... ........... .......... ........... ..... . 17

2.8.3.1 Area of structure for calculation of transverse wind load, At ................ 18

2.8.3.2 Calculation of drag coefficients, Cd...................................................18

2.8.4 Longitudinal Wind Load.... ........... ........... ...... ........... ........... .......... .. 19

2.8.5 Vertical Wind Load........................................................................ 20

2.9 Thermal Effects................................................................................................ 20

2.9.2 Variation in Average Bridge Temperature.......... ........... ........... ...... .... 20

2.9.3 Differential Temperatures. ........... .......... ........... ....... ....... ....... ....... ...22

2.13 Earthquake Forces...........................................................................................23

2.13.1 General.........................................................................................23

2.13.2 Earthquake Resistant Design.......... ........... .......... . ........ ....... ....... .... 23

2.13.4 Equivalent Quasi-Static Earthquake Forces....... ........... ........... ... ..... . 23

2.19 Road Signs and Lighting Structures .......... ........... ........... .......... ........... ........... ... 24

2.19.3 Design Wind Speeds ..................................................................... 24

2.19.3.2 Ultimate Limit State .......... ........... ........... .......... ........... ........... ..... ..24

2.19.4 Design Wind Pressure ...................................................................24

Section 3 Foundations...................................................................................................26

Section 4 Bearings And Deck Joints ..............................................................................26

Section 5 Concrete

5.1 Scope and General ........... ........... .......... ........... ........... .......... ....... ....... ...... .......27

5.1.1 Scope and Application ...................................................................27

5.1.1.2 Application .................................................................................... 27

5.1.5 Construction..................................................................................27

5.2 Design Requirements and Procedures.... .......... ........... ....... .......... ........... ........... 27


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5.2.4 Design for Serviceability. ........... ........... ......... .......... ........... .......... . . 27

5.2.4.3 Cracking....................................................................................... 27

5.4 Design for Durability......................................................................................... 28

5.4.3 Exposure Classification ................................................................. 28

5.4.10 Requirements for Cover to Reinforcing Steel and Tendons .... ... .... .... .. 29

5.4.10.3 Cover for corrosion protection .......... ........... ........... ....... ........ ........ .. 29

5.6 Design Properties of Materials................... ........... .. .......... ........... .......... . ...... ..... 295.6.1 Properties of Concrete ........... .......... ........... .......... ........... ........... ... 29

5.6.1.1 Strength ....................................................................................... 29

5.6.1.7 Shrinkage..................................................................................... 29

5.6.1.8 Creep 29

5.6.2 Properties of Reinforcement ........... ........... .......... ....... ....... ...... ....... 29

5.6.2.1 Strength ....................................................................................... 29

5.6.3 Properties of Tendons......... ........... ........... . .......... ........... ........... .... 30

5.6.3.1 Strength ....................................................................................... 30

5.6.3.2 Modulus of elasticity...................................................................... 30

5.6.3.4 Relaxation of tendons ........... ........... .......... .......... ........... ........... .... 30

5.13 Stress Development and Splicing of Reinforcement and Tendons... .... .... ... .... ... .... . 31

5.13.1 Stress Development in Reinforcement ........... ........... .......... ....... ...... 31

5.13.1.2 Development length for bar in tension. ........... ........... .......... ....... ...... 31

5.14 Joints, Embedded Items, Fixings and Connections ........... ........... .......... ....... ...... 31

5.14.2 Embedded Items and Holes in Concrete...... ........... ........... .... ...... .... 31

5.14.2.2 Limitations of materials .......... ........... ........... .......... ........... ........... .. 31

5.16 Material Requirements...... ........... ........... .... ........... ........... .......... ....... ....... ....... . 31

5.16.1 Material Requirements for Concrete and Grout.. ........... ........... ........ . 31

5.16.1.1 Materials for concrete and grout................ ........... ..... ....... ....... ....... . 31

5.16.1.2 Normal-class concrete......... ........... .......... .. .......... ........... ........... ... 33

5.16.2 Material for Reinforcing Steel... ........... ........... ....... ....... ....... ....... ..... 33

5.16.2.1 Reinforcement...... ........... ........... .... .......... .......... ........... . ...... ...... ... 33

5.16.3 Material Requirements for Prestressing Ducts, Anchorages and

Tendons .............................................................................. 33

5.16.3.4 Tendons. ...................................................................................... 33

Appendix 5A Reference Documents .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... ..... ..... .. 34

Section 6 Steel And Composite Construction

6.2 Materials 35

6.2.1 Yield Stress and Tensile Stress used in Design...... ....... ....... ........ ... 35

6.2.4 Fasteners ..................................................................................... 38

6.3.8 Design for Fire Resistance............................................................. 38

Section 7 Rating .................................................................................................. . 39

Railway Supplement To Sections 1-5

1.1 General Principles............................................................................................ 39

1.1.1 Applicability.................................................................................. 39


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PART A LIST OF AMENDED CLAUSES

IN THE BASE DOCUMENT

Sections 1 to 7:

1.1.1....................... (General Principles) Applicability

1.3.1......................... (Geometric Requirements) Bridge Carriageway Widths

1.3.2......................... Edge Clearances for Bridges Without Footways

1.3.4......................... Vertical Clearance at Structures

1.10.......................... Australian Standards

2.3.3......................... (Traffic Loading) L44 Lane Loading

2.3.4......................... (Traffic Loading) Heavy Platform Loading

2.3.5.2 ...................... (Position of Loads) Heavy load Platform loadings

2.3.8......................... Fatigue Loading

2.4.2......................... (Dynamic Load Allowance) T44 Truck and L44 Lane Loading

2.5.2......................... (Horizontal Forces) Braking Forces2.5.4.........................Minimum Lateral restraint Capacity – Ultimate Limit State

2.8 ............................Wind Loads (incl. All sub-clause s)

2.9.2......................... (Thermal effects) Variation in Average Bridge temperature

2.9.3......................... (Thermal effects) Differential temperatures

2.13.1....................... (Earthquake Effects) General

2.13.2.......................Earthquake Resistant Design

2.13.4.......................Equivalent Quasi-static Earthquake Forces

2.19.3....................... (Road Signs and lighting Structures) Design Wind Speeds

2.19.4.......................Design Wind Pressure

5.1.1.2 ...................... (Scope and Application) Application

5.1.5......................... (Scope and Application) Construction

5.2.4.3 ...................... (Design for Serviceability) Cracking

5.4.3......................... (Design for Durability) Exposure Classification5.4.10.3.................... (Design for Durability) Cover for Corrosion Protection

5.6.1.1 ...................... (Properties of Concrete) Strength

5.6.1.7 ...................... (Properties of Concrete) Shrinkage

5.6.1.8 ...................... (Properties of Concrete) Creep

5.6.2.1 ...................... (Properties of Reinforcement) Strength

5.6.3.1 ...................... (Properties of Tendons) Strength

5.6.3.2 ...................... (Properties of Tendons) Modulus of Elasticity

5.6.3.4 ...................... (Properties of Tendons) Relaxation of Tendons

5.13.1.2.................... (Stress Development in Reinforcement) Development Length for Bar in

Tension

5.14.2.2.................... (Embedded Items and Holes in Concrete) Limitations of Materials

5.16.1.1.................... Materials for Concrete and Grout

5.16.1.2.................... (Material Requirements for Concrete and Grout) Normal-class Concrete

5.16.2.1.................... (Material Requirements for Reinforcing Steel) Reinforcement

5.16.3.4.................... (Material Requirements for Prestressing Ducts , Anchorages and Tendons)

Tendons

5A............................ Appendix 5A Reference Documents

6.2.1......................... Yield Stress and Tensile Stress Used in Design

6.3.8......................... Design for Fire Resistance

Railway Supplement to Sections 1 - 5


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1.1.1..........................(General Principles) Applicability


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PART B TEXT OF AMENDED CLAUSES

IN THE BASE DOCUMENT

SECTION 1 GENERAL

1.1 General Principles

1.1.1 Applicability

Add the following paragraph between paragraphs 2 and 3:

“The Cambodian Bridge Design Standard has been prepared for the design of road,

rail and pedestrian bridges and other bridge- related structures under the jurisdiction ofthe Cambodia Ministry of Public Works and Transport, referred to in this document

as the Authority, and also for use by other Authorities and organisations.”

1.3.1 Bridge Carriageway Widths

Page 1.4, Para 2, line 4: replace “600 mm” by “500 mm.”

1.3.2 Edge Clearances for Bridges Without Footways

Replace existing Table 1.3.2 with the following Table:

Table 1.3.2 Edge Clearances for B ri dges Without Footways.

TYPE OF ROAD DESIGN

STANDARD

EDGE CLEARANCE

(EACH SIDE)

Low volume, 2 lane roads,

Projected ADT < 150 vehicles/day

R1,

U1

No clearance minimum,

250 mm preferred

Medium volume, 2 lane roads,

Projected ADT 150 to 3000 vehicles/day

R2, R3

U2, U3

250 mm minimum,

500 mm preferred

High volume, 2 lane roads,

Projected ADT >3000 vehicles/day

R4, R5, R6

U4, U5, U6

500 mm minimum,

1000 mm preferred

Note:

Traffic volumes are the expected Annual Average Daily Traffic volumes 30 years ahead.

Design standards are defined in the Cambodian Road Design Standard Part 1 – Geometry.

1.3.4 Vertical Clearance at Structures

In the last paragraph, replace “AS 1742.2” with “the appropriate Authority”.


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1.10 Australian Standards

Delete “Australian” from the first paragraph.

Add the following paragraph:

“References to Australian Standards may generally be replaced by references to an

equivalent or similar standard from another country. Where specific provisions of

Australian Standards are required, these standards are either adopted in their original

form as a Cambodian Standard, or the relevant provisions are reproduced in the textof this Standard.”


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SECTION 2 DESIGN LOADS

2.3 Traffic Loading

2.3.3 L44 Lane Loading

Replace the Article as follows:

“The T44 Lane Loading shall consist of a uniformly distributed load as given in Figure

2.3.3 together with a tandem of two concentrated loads 90 kN each spaced at 1.20

m. The L44 Lane Loading shall be considered as uniformly distributed over the width

of a 3 m Standard Design Lane.

For continuous spans the L44 Lane Loading shall be continuous or discontinuous asmay be necessary to produce maximum effects, and the tandem of concentrated loads

shall be placed in such a position as to produce maximum effects. Only one tandem ofconcentrated loads shall be used per lane except that one additional tandem of

concentrated loads of equal force shall be placed in each lane in one other span in the

series in such a position as to produce maximum negative moment. The L44 LaneLoading does not apply for spans less than 10 m.”

2.3.4 Heavy Load Platform Loading

Replace the whole of Article 2.3.4 with the following:

“(a) The HLP 240 design loading shall be applied to bridges on the following road

categories:

- Expressways

- Highways

- Provincial Roads

- Collector Roads

- Arterial Roads

These roads generally will comply with design standards R6/U6, R5/U5 and

R4/U4 of the Cambodian Road Design Standard Part 1 – Geometry.

(b) For a bridge on any other road category, the Authority shall determine if the

bridge shall be designed for the effects of Heavy Load Platform loadings.

(c) For bridges on special designated routes, as determined by the Authority, aheavy load configuration, which shall be specified by the Authority, shall beapplied.

(d) The Heavy Load Platform (HLP) loadings shall have the following configurations:

i. 12 rows of axles (HLP 240).


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ii. The total load per axle shall be 200 kN. The axle load shall be equally

distributed among all wheels.

iii.Axles shall be spaced at 1.8 m centres.

iv. 8 tyres per axle row.

v. The overall width of axles shall be 3.6 m. The lateral spacing of dual wheels

along an axle shall be as shown in Figure 2.3.4.

vi. For continuous bridges, the loading may be separated into two groupsof 6 axles (HLP 240) with a central gap of between 6 m and 15 m,

the gap being chosen to give the most adverse effect.

vii. The tyre contact area for each individual wheel shall be assumed to be

500 mm x 200 mm.”

HLP 240

12 axles @ 200 kN spaced at 1.80 m = total 2400 kN

Overall length 19.80 m

ELEVATION VIEW

1400 mm 1400 mm

3600 mm

END VIEW OF AN HLP AXLE

400500 500 500800400 500

F igur e 2.3.4 Heavy Load Platform Loading


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2.3.5 Number of Lanes for Design and Lateral Position of

Loads

2.3.5.2 Heavy load platform loading

Replace the first paragraph with the following:

“The HLP 240 Heavy Load Platform loading shall be assumed to centrally occupy

two Standard Design Lanes.”

2.3.8 Fatigue Loading

Replace Table 2.3.8 with the following:

Table 2.3.8 Fatigue Stress Cycles for Tr aff ic L oadings

Number of fatigue stress cycles for bridges on roads ofcategory:

Fatigue design trafficloading

Category R6/U6:

Expressways, Highways,

Arterial Roads

All other roads

W7 Wheel loading 2,000,000 500,000

T44 Truck loading 500,000 100,000

L44 Lane loading 100,000 100,000

2.4.2 Dynamic Load Allowance -T44 Truck and L44 Lane

loading

The Dynamic Load Allowance for T44 and L44 loadings shall be 0.35, unless alternative

values based on tests or on dynamic analysis are approved by the Authority.

2.5.2 Braking forces.

For the lengths of the structures between 10m and 60m, the braking force will be:

300 kN + (L-10) m x 6 kN/m

Replace existing Figure 2.5.2 with the Figure on the following page:


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0

100

200

300

400

500

600

700

0 10 20 30 40 50 60 70

Length of structure considered(m)

B r a k i n g

f o r c e ( k N )

F igur e 2.5.2 Braking Forces

2.5.4 Minimum Lateral Restraint Capacity - Ultimate Limit State

Replace paragraph three with the following:

“Restraints shall have sufficient lateral clearance to allow thermal movements,

especially on wide and curved superstructures. The restraint system for each

continuous section of superstructure shall be capable of resisting an ultimate design

horizontal force normal to the bridge centreline of 200 kN or 5% of the superstructur e

dead load at that support, whichever is greater.

For all bridges over roads, vehicular accesses, railways and navigable waters, the

restraint system shall be designed for an ultimate lateral load of 500 kN in accordance

with the following criteria:

1. Bridges over roads and vehicular accesses. Where the clearance between themaximum legal load and the underside of the structure is less than 3.5 m, the 500 kN

load shall be applied to the superstructure within the width of the road formation.

2. Navigable waters. Where the clearance between the top of the design vessel,

excluding masts and aerials, to the underside of the bridge superstructure is less than3.5 m, the load shall be applied to the superstructure within the width of the navigable

waters.

3. Railways. Where the clearance from the railways clearance zone to the underside

of the superstructure is less than 3.5 m, the load shall be applied to the superstructurewithin the width of the railway clearance zone plus 10 m either side of the railway

clearance zone.”


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2.8 Wind Loads

The whole of Article 2.8 shall be replaced with Clauses 2.8.1 to 2.8.5 as follows:

2.8.1 General

Designing for wind loading is to be based on a static analysis, which is essentially a quasi-

steady analysis approach using a design gust wind speed in conjunction with a mean loading

coefficient. The gust wind speed is the maximum wind speed, averaged over a period of 2to 3 seconds which occurs in one hour. This approach is limited to conventional structures,

(nominally having a first-mode frequency of vibration of less than 1 Hz). For wind sensitive

structures such as suspension or long-span cable-stayed bridges, which may be subject to

significant wind excited dynamic response, special investigations into the dynamic behaviour

of the structure should be carried out.

The methodology for determining the wind loading here is based on the 92' AUSTROADS

Bridge Design Code and the Australian Standard for Wind Loading, AS 1170.2, to whichacknowledgments are made.

2.8.2 Basic design wind speed

The basic gust design wind speeds that shall be used are referenced to a standard exposure

of 10m height above open country terrain, for Serviceability and Ultimate Limit State design

conditions, defined by 20 and 2000 year Return Periods respectively. These are given for

the three Cambodian Regions in Table 2.8.2.

TABL E 2.8.2 Basic Gust Design Wind Speeds (m/sec)

Region Description Serviceability

Limit State

Vs

Ultimate

Limit State

Vu

A Coastal Region within 50 km from the

coast

Coasta l Region for 50 to 100 km from the

coast

35

35

60

50

B Coastal Region beyond 100 km from the

coast and Flat Land Region 35 45

C High Land 35 45

2.8.2.1 Derivation of site design gust wind speed (Vz)

The design gust wind speed (Vz) at the site and for height, z , shall be calculated from theappropriate limit state basic wind speed given in Table 2.8.2 as follows:


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Vz = V M(z,cat) Mt

Where

Vz = The site design gust wind speed at height z, in metres per

second

V = The basic wind speed, (Vu) or (Vs) (see Table 2.8.2), in

metres per second

M(z,cat ) = A gust wind speed multiplier at height z for a terrain

category with upwind distance of at least 2500 m (see

Table 2.8.2.3)

Mt = A topographic multiplier which shall be 1.0 if the

approaching slopes are less than 0.05.

Note: M z,cat may change from the tabulated values if the structure site is within

the transition zone near the edge of a terrain boundary (see Clause

2.8.2.4)

Irrespective of the calculation in this Clause, the ultimate limit state site design gust wind

speed (Vz), shall not be less than 30 m/sec.

For serviceability limit state wind loads in conjunction with traffic loads on a structure, the

selection of a wind speed for a specified return interval is not appropriate and the designwind speed shall be taken as 35 m/sec in all locations. The effect of wind on the traffic load

need not be considered.

2.8.2.2 Terrain Category

Terrain, over which the approach wind flows towards a structure, shall be assessed on the basis of the following category descriptions:

(a) Category 1 Exposed open terrain with few or no obstructions and water

surfaces at serviceability wind speeds (Vs) only.

(b) Category 2 Open terrain, grassland with few well scattered obstructions

having heights generally from 1.5m to 10.0m and water

surfaces for Vu.

(c) Category 3 Terrain with numerous closely spaced obstructions having the

size of domestic houses (3.0m to 5.0m high).

(d) Category 4 Terrain with numerous large, high (10.0m to 30.0m high) and

closely spaced obstructions such as large city centres and

well-developed industrial complexes.

Selection of terrain category shall be made with due regard to the permanence of the

obstructions which constitute the surface roughness, in particular vegetation in tropical

cyclonic regions shall not be relied upon to maintain a wooded terrain roughness.


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2.8.2.3 Terrain and structure height multiplier (M (z,cat) )

The variation of terrain multipliers with height (z) shall be taken from Tables 2.8.2.3.(A) and

2.8.2.3 (B). Designers shall take account of probable future changes to terrain roughness in

assessment of terrain and structure height multipliers M (z,cat)

TABLE 2.8.2.3 (A) Terrain and Structure Height Mul tipli ers for Gust

Wind Speeds in Ful ly Developed Terrains in Region A

Height (z) Multiplier M (z,cat)

M Terrain Category 1&2 Terrain Category 3&4

≤ 35

10

15

20

30

40

50

75

≥ 100

0.90

0.95

1.00

1.07

1.13

1.20

1.25

1.29

1.35

1.40

0.80

0.80

0.89

0.95

1.05

1.15

1.25

1.29

1.35

1,40

TABLE 2.8.2.3 (B) Terrain and Structure Height Mul tipli ers for Gust

Wind Speeds in Ful ly Developed Terrains in Regions B & C

Multiplier M (z,cat)Height (z)

MTerrain

Category 1

Terrain

Category 2

Terrain

Category 3

Terrain

Category 4

≤ 35

10

15

20

30

40

0.99

1.05

1.12

1.16

1.19

1.22

1.24

0.85

0.91

1.00

1.05

1.08

1.12

1.16

0.75

0.75

0.83

0.89

0.94

1.00

1.04

0.75

0.75

0.75

0.75

0.75

0.80

0.85


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50

75

100

150200

1.25

1.27

1.29

1.311.32

1.18

1.22

1.24

1.271.29

1.07

1.12

1.16

1.211.24

0.90

0.98

1.03

1.111.16

2.8.2.4 Changes in terrain category

Where, for the direction under consideration, the wind approaches across ground

with changes in terrain category within 2500 m of the structure, M (z,cat) shall betaken as the weighted average terrain and structure height multiplier over the

2500m upwind of the structure at height z above ground level.

For evaluation at height z , a change in terrain incorporates a lag distance ( x i)25.1

,

,3.0

=

r o

r oi z

z z x

z o,r = larger of the two roughness lengths at a boundary between roughnesses (given in

Table 2.8.2.4)

z = height of the structure for which the design velocity is required.

Note: For height less than 10m the lag distance should be taken as 1.0.

TABLE 2.8.2.4 Roughness Lengths for Terrain Categor ies

Terrain category Roughness length (m)

Terrain category 1 0.002



Terrain category 4 2

The weighted average of Mz,cat is weighted by the length of each terrain upwind

of the structure allowing for the lag distance at each terrain category change for a

distance of 2500 m, as shown in Figure 2.8.2.4.


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2500

33,44,22,

,

t z t z t z

cat z

x M x M x M M

++= for the case illustrated

F igure 2.8.2.4 Changes in Terrain Category

2.8.2.5 Topographic multiplier (Mt)

For bridge sites approach slopes are usually less than 0.05, and for which Mt = 1.0.

However, if approach slopes are greater than 0.05 the Topographic Multiplier from Table3.2.8 in AS 1170.2-1989 shall be used.

2.8.3 Transverse wind loadThe transverse wind load shall be taken as acting horizontally at the centroids of theappropriate areas, and shall be calculated as follows:

(a) Serviceability design transverse wind load Wt s*

Wt s* = 0.0006 Vs2 At Cd (kN)

(b) Ultimate design transverse wind load Wtu*

Wtu* = 0.0006 Vu At Cd (kN)

where:

Vs = design wind speed for Serviceability Limit States (m/sec)

Vu = design wind speed for Ultimate Limit States (m/sec)

At = area of the structure for calculation of wind load (m2)

Cd = drag coefficient.

2500 m

lag distance

x i tc3 / tc4

Terrain cat 3 Terrain cat 4 Terrain cat 2

lag distance

xi tc4 / tc2

xt3 x t4 x t2

z z

Wind direction


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2.8.3.1 Area of structure for calculation of transverse wind load, At

The area of the structure or element under consideration shall be the solid area in normal

projected elevation subject to the following provisions:

(a) Superstructures with solid parapets

The area of the superstructure shall include the area of the solid windward parapet,

but the effect of the leeward parapet need not be considered.

(b) Superstructures with open parapets

The total load shall be the sum of the loads for the superstructure, the windward

barrier and the leeward barrier considered separately. Where there are more than

two parapets or safety fences, irrespective of the width of the superstructure, only

those two elements having the greatest unshielded effect shall be considered.

(c) Piers

Shielding shall not be considered.

2.8.3.2 Calculation of drag coefficients, Cd

(a) Drag coefficient for all superstructures with solid elevation

For superstructures with or without traffic load, C d shall be derived from

Figure 2.8.3.2 where

b = depth of bridge between outer faces of parapets

d = depth of superstructure (including solid parapet if applicable).

(b) Drag coefficient for truss girder superstructures

The wind force on truss girder superstructures shall be calculated by considering each

component individually, using the drag coefficients C d from Appendix B in AS 1170.2.

(c) Drag coefficients for beams during erection

The drag coefficient for beams and girders during erection stages shall be calculatedfor individual beams using Figure 2.8.3.2. Shielding shall not be considered for

individual beams, but may be allowed for when two or more beams are connected, provided the ratio of the clear distance between beams to the depth does not exceed

7. Under such circumstances, the drag coefficient for the combination may be taken

as 1.5 times the value for an individual beam.


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(d) Drag coefficient for parapet railings, parapet barriers and substructures.

Drag coefficients shall be obtained from Appendix B in AS 1170.2.

F igur e 2.8.3.2 Drag Coeff icient C d for Superstructur es with Soli d

Elevation

NOTES

1. The values given assume a vertical elevation and a horizontal wind

2. Where the windward face is inclined to the vertical, the drag coefficient Cd may be reduced by

0.5% per degree of inclination from the vertical, subject to a maximum reduction of 30%.

3. Where the windward face consists of a vertical and a sloping part or two sloping parts inclined

at different angles, the wind load shall be derived as follows:

(a) The basic drag coefficient Cd is calculated using the total depth of the structure.

(b) For each non-vertical face, the basic drag coefficient calculated above is reduced in

accordance with Note 2.

(c) The total wind load is calculated by applying the appropriate drag coefficients to the

relevant areas.

4. Where a superstructure is superelevated, Cd shall be increased by 3% per degree of inclination

to the horizontal, but not by more than 25%.

5. Where a superstructure is subject to wind inclined at not more than 5 degrees to the horizontal,

Cd shall be increased by 15%. Where the angle of inclination exceeds 5 degrees, the drag

coefficient shall be derived from tests.

6. Where a superstructure is superelevated and also subject to inclined wind, the drag coefficient

shall be the subject of special investigation.

2.8.4 Longitudinal Wind Load

For piers, truss bridges and other superstructure forms which present a significant surface

area to wind loads parallel to the longitudinal centreline of the structure, a longitudinal wind


23/67




load shall be considered. The serviceability and ultimate design longitudinal wind loads shall

be calculated in a manner similar to those for transverse wind loads.

Longitudinal wind loads on the superstructure may also be significant during the construction

stage of some bridge types which are not affected by these loads at normal service levels.

2.8.5 Vertical Wind Load

An upward or downward vertical wind load, acting at the centroid of the appropriate area,

shall be calculated as follows:

(a) Serviceability design vertical wind load W vs* (kN)

Wvs* = 0.00045 Vs

2 A p

(b) Ultimate design vertical wind load W vu* (kN)

Wvu* = 0.00045 Vu

2 A p

whereVx = design wind speed for Serviceability Limit States (m/sec)

Vu = design wind speed for Ultimate Limit States (m/sec)

A p = bridge area in plan (m2).

The above relationships may be used provided the angle of inclination of the wind to the

structure is less than 5 degrees. For inclinations in excess of 5 degrees, the lift coefficientshall be investigated by testing.

2.9 Thermal Effects

2.9.2 Variation in Average Bridge Temperature

Second paragraph, delete the following sentence:

“eg frost pockets and sheltered low-lying areas where the minimum shade air

temperature may be substantially lower”

Replace the Table 2.9.2 (a) with the following:


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Table 2.9.2 (a) Shade Ai r Temperatures

SHADE AIR TEMPERATURES ( 0 C)

CLIMATIC REGION (1) Maximum Minimum

Coastal (2)

Flat Land and High Land (3)

40

42

11

8

Notes: 1) For the extent of climatic regions refer to Figure 2.9.2

2) For locations less than 20 km from the sea coast the maximum temperature

may be reduced by 2 0 C and the minimum temperature increased by 3 0 C

3) For locations with altitude greater than 1000 m above the sea level the

maximum temperature shall be reduced by 10 0 C and the minimum

temperature shall be reduced by 5 0 C.


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Add the following Figure 2.9.2:

F igur e 2.9.2 Climatic Regions in Cambodia

2.9.3 Differential Temperatures.

In Figure 2.9.3, replace the “Regional Values for T” and associated information with the

following:

LOCATION OF THE BRIDGE T

1. All locations less than 500 m above sea level

2. All locations more than 500 m above sea level

13 0C

18 0C


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2.13 Earthquake Forces

2.13.1 General

Replace the whole of the Clause with the following:

“There are no records of seismographs inside Cambodia in the World Earthquake

database. Information gathered in neighbouring countries indicates there are no

recorded epicentres in Cambodia.

A uniform acceleration coefficient of a = 0.05 is considered to be appropriate

throughout Cambodia.”

2.13.2 Earthquake Resistant Design

Insert between the second and the third paragraph:

“As a minimum requirement for conditions prevailing in Cambodia, the ends of deck at

abutments and at piers of simply supported structures shall allow for a minimum 200

mm of horizontal displacement additional to displacements calculated for otherloadings, without falling off the edge of the support.”

2.13.4 Equivalent Quasi-Static Earthquake Forces

(a) Seismicity factor, α

Delete Table 2.13.4.1 and replace the text with the following:

“The value of Seismicity Factor shall be determined by the application of the following

relationship to the acceleration coefficient, a:

For a # 0.08 α = 0.13”

(e) Site-structure resonance factor, S

Replace the text with the following:

“The Site-Structure Resonance Factor shall be either taken as 1.5 or determined from

Table 2.13.4 (e):


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Tabl e 2.13.4.(e) Site-Structu re Resonance Factors

SOIL PROFILE SITE-STRUCTURE

RESONANCE

FACTOR S

A profile of rock materials with rock strength low or better 0.67

A soil profile with either;

(a) Rock material with extreme low or very low strength

characterised by shear wave velocities greater than 760 m/sec, or

(b) not more than 30 m of :medium dense to very dense coarse

sands and gravels;

firm, stiff or hard clays; or

controlled fill

1.0

A soil profile with more than 30 m of :

Medium dense to very dense coarse sand and gravels :

Firm, stiff or hard clays; or

Controlled fill

1.25

A soil profile with a total depth of 20 m or more and containing 6 to 12 m

of:

Very soft to soft clays;

Very loose or loose sands;

Silts; or

Uncontrolled fill

1.5

A soil profile with more than 12 m of;

Very soft to soft clays:

Very loose or loose sands;

Silts; or

Uncontrolled fill characterised by shear wave velocities less

than 150 m/sec

2.0

2.19 Road Signs and Lighting Structures

2.19.3 Design Wind Speeds

2.19.3.2 Ultimate Limit State

Replace the first line with the following:

“The basic design gust wind speed shall be:”

Replace “200 year return interval wind speed *” with “ 0.85 Vu* ”

Replace “* Determine from AS 1170.2” with “ The design wind speed, Vu, shall be

determined from Clause 2.8.2.1 which includes the application of height and topographical

multipliers.”

2.19.4 Design Wind Pressure

The design wind pressure q* (kPa), for Serviceability or Ultimate Limit States, may be

calculated using the following equivalent dynamic pressure approach:


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32* 1061.0 −= V C Q d where

V = the basic wind speed (VU) or (VS) (see Table 2.8.2), in metres per second.

Cd = drag coefficient, determined from AS1170.2 or Table 2.19.4, as appropriate.

Note: For tall slender structures, such as high masts, the equivalent dynamic pressure

approach may be unconservative. As an alternative the gust-energy or gust-factor method of determining design wind loads may be employed.


29/67




SECTION 3 FOUNDATIONS

The AUSTROADS Code includes provisions for the determination of ultimate pile

resistance design of pile footings by a choice of methods, including static analysis, dynamic

analysis or static load testing, and provides the appropriate material factors fordetermination of the design resistances.

In view of the broad range of acceptable methods, which also include the current practice

in Cambodia, it is not considered necessary to modify this Section.

The following Australian Standards referred to in the text have been replaced:

AS 2042 replaced by AS 2041

AS1342 replaced by AS 4058

SECTION 4 BEARINGS AND DECK JOINTS

There are no amendments to Section 4 except that AS 1511, referred to in Clause 4.14.3,has been replaced by AS 4100.

Refer to Section 4 Commentary for revised Articles C4.3 and C4.17


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SECTION 5 CONCRETE

5.1 Scope and General

5.1.1 Scope and Application

5.1.1.2 Application

Add after (a):

“Compressive strength of concrete is defined in this Code on the basis of tests carried

out on standard test cylinders 150 mm diameter by 300 mm long. Where concrete

strength is to be determined on the basis of tests carried out on samples of other

dimensions, this fact shall be clearly stated on the drawings and in the specification.

Where standard 150 mm x 150 mm x 150 mm concrete cubes are used for testing,the equivalent standard cylinder strength may be obtained from:

''

10'

15log2.076.0 cube

cubec f

f f

+=

5.1.5 Construction

Add the following paragraph at the end of the Article:

“The tolerances for position and size of the structure and members are reproduced in

Clause C5.15. More stringent tolerances may be required for reasons ofserviceability, fit of components, or aesthetics of the structure. These will be specified

in the Construction Specifications issued by relevant Authorities.”

5.2 Design Requirements and Procedures

5.2.4 Design for Serviceability

5.2.4.3 Cracking

Refer to the Commentary for examples of additional requirements stipulated by some RoadAuthorities in Australia to supplement the requirements related to cracking.


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5.4 Design for Durability.

5.4.3 Exposure Classification

Replace the existing Table 5.4.3 with the new Table 5.4.3.

Table 5.4.3 Exposure Classif ications

SURFACE AND EXPOSURE ENVIRONMENT EXPOSURE

CLASSIFICATION

1 SURFACES OF MEMBERS IN CONTACT WITH THE GROUND (Note

1)

(a) Members in non-aggressive soil (Note 2)

(b) Members protected by a damp-proof membrane

(c) Members in aggressive soils (Note 3)

B1

A

U

2 SURFACES OF MEMBERS IN INTERIOR ENVIRONMENT

Fully enclosed within a structure except for a brief period of

weather exposure during construction. A

3 SURFACES OF MEMBERS IN ABOVE-GROUND EXTERIOR

ENVIRONMENTS IN AREAS THAT ARE:

(a) Inland & near-coastal (> 1 km from coastline).

(b) Coastal (Up to 1 km from coast -line but excluding tidal and

splash zones) (Note 4).

B1

B2

4 SURFACES OF MEMBERS IN WATER (Note 1)

(a) In fresh water

(b) In sea water or ground water containing salt:

(i) permanently submerged

(ii) In tidal or splash zone

(c) In soft or running water

B1

B2

C

U

5 SURFACES OF MEMBERS IN OTHER ENVIRONMENTS

Any exposure environment not described in Items 1 to 4 above UNote s: 1) Members, such as piles without permanent steel casing, shall be classified as members

in water unless it is proved by geotechnical investigation that no part of the member is

below the permanent water table level.

2) If testing has been undertaken to ascertain that the soil in contact with concrete is non-

aggressive, then exposure classification A may be used, provided that the soil is not

subject to wetting and drying. Typically, members in the top 500 mm of soil would not

qualify for this reduction.

3) Permeable soils with pH < 4.0 or with ground level containing more than one gram per litre

of sulphate ions, would be considered aggressive.

4) For the purpose of this Table, the coastal zone includes locations within 1 km of the

shoreline of the large expanses of salt water, eg river deltas affected by tides. Where thereare strong prevailing winds or vigorous surf, the distance should be incr eased beyond 1

km and higher levels of protection should be considered. Proximity to small salt water

bays, estuaries and rivers may be disregarded, except for structures immediately over or

adjacent to such bodies of water.


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5.4.10 Requirements for Cover to Reinforcing Steel and

Tendons

5.4.10.3 Cover for corrosion protection

Add at the end of Clause 5.4.10.3 (b):

“In cases where the standard of formwork is likely to be lesser than specified by

AS 3610 - Formwork for Concrete, the values in Table 5.4.10.3 (A) shall be suitably

increased.”

5.6 Design Properties of Materials

5.6.1 Properties of Concrete

5.6.1.1 Strength

Add at the end of this Clause:

“For the definition of the compressive strength of concrete refer to Clause 5.1.1.2.”

5.6.1.7 Shrinkage

For the applicability of the curves for the shrinkage coefficient k 1 appropriate for the relative

humidities applicable in Cambodia refer to clause C5.6.1.7.

5.6.1.8 Creep

For the applicability of the curves for the creep factor coefficient k 2 appropriate for the

relative humidities applicable in Cambodia refer to clause C5.6.1.8.

5.6.2 Properties of Reinforcement

5.6.2.1 Strength

Add the following paragraph after the existing first paragraph:

“Reinforcing bars, steel hard drawn wires and welded wire fabric to the ASTM

Standards may be also used follows:

Type Australian Standard ASTM Standard

Deformed bars AS 1302 A 615 Grade 60*

Steel wire AS 1303 A 185

Welded wire fabric AS 1304 A 82

* Bars to A 615 are not weldable.”


33/67


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5.13 Stress Development and Splicing of Reinforcement

and Tendons

5.13.1 Stress Development in Reinforcement

5.13.1.2 Development length for bar in tension.

(b) Deemed-to-comply development length

Add the following:

“(vi) f sy does not exceed 400 MPa.”

5.14 Joints, Embedded Items, Fixings and Connections

5.14.2 Embedded Items and Holes in Concrete

5.14.2.2 Limitations of materia ls

In Article (a) replace “AS 3600” by “the Authority”.

5.16 Material Requirements

5.16.1 Material Requirements for Concrete and Grout

5.16.1.1 Materials for concrete and grout

(a) Portland Cement

Add the following at the end of the sub-clause:

“Cement complying with ASTM C150 Standard Specification for Portland Cement

Type I would also be acceptable.”

(b) Blended cements.


“ASTM C595M Standard Specification for Blended Hydraulic Cements (Metric) is

the nearest equivalent ASTM specification that covers blended cements. It contains

more types than the Australian Standard.”

(c) Fly ash.

Replace “AS 3583.1” with “AS 3582.1”.


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“The ASTM C618 Standard Specification for coal Fly Ash and Raw or Calcined

Natural Pozzolan for Use as a Mineral Admixture in Concrete is the nearest

equivalent.”

(d) Slag.

Replace “AS 3972” with “AS 3582.1”.


“The ASTM C989 Standard Specification for Ground Granulated Blast Furnace Slag

for Use in Concrete and Mortars is the nearest ASTM equivalent.”

Add new sub-clause after (d) as follows:

“(e) Silica fume

Silica fume shall comply with AS 3582.3

The ASTM C 1240 Standard specification for Silica Fume for Use as a Mineral

Admixture in Hydraulic Cement, Concrete, Mortar and Grout is the nearest

equivalent.”

Renumber existing sub-clause (e) as follows:

“(f) Aggregates”

and add the following to the end of the renumbered sub-clause:

“ASTM C33 Standard Specification for Concrete Aggregates is the nearest

equivalent ASTM standard.”

Renumber existing sub-clause (f) as follows:

“(g) Water ”

Renumber existing sub-clause (g) as follows:

“(h) Chemical admixtures”

and add the following to the end of the renumbered sub-clause:

“ASTM C494 Standard Specification for Chemical Admixtures in Concrete is thenearest equivalent standard. Other relevant ASTM Standards are ASTM C260


36/67




Standard Specification for Air-entraining Admixtures of Concrete and ASTM C1017

Standard Specification for Chemical Admixtures for Use in Producing Flowing

Concrete.

Cellulose-type chemical water thickeners may be used in grout (See SAA MP 20

Part 3).”

Renumber existing sub-clause (h) as follows:

“(i) Other materials”

5.16.1.2 Normal-class concrete

Replace Article 5.16.1.2 (d)(i) with the following:

“Cement shall comply with AS 3972 alone or in combination with one or more

cementitious materials.”

5.16.2 Material for Reinforcing Steel

5.16.2.1 Reinforcement

At the end of the Article, add the following:

“Alternative ASTM Standards are listed in Article 5.6.2.1.”

5.16.3 Material Requirements for Prestressing Ducts,

Anchorages and Tendons

5.16.3.4 Tendons.

At the end of the first paragraph add the following:

“The nearest equivalent ASTM standards are:

ASTM 416-96 Standard Specification for Steel Strand, Uncoated Seven-Wire

for Prestressed ConcreteASTM A722-97 Standard Specification for Uncoated High-Strength Steel Bar for

Prestressing Concrete.

ASTM A882/A882M-96 Standard Specification for Epoxy-Coated Seven-WirePrestressing Steel Strand.

ASTM A886/A886M-96 Standard specification for Steel Strand, Indented, Seven-Wire Stress-Relieved for Prestressed Concrete.”


37/67




Appendix 5A Reference Documents

Add the following references:

“AS 3582.1 Supplementary Cementitious Materials for use with Portland and

Blended Cement - Fly Ash AS 3582.2 Supplementary Cementitious Materials for use with Portland and

Blended Cement - Ground Granulated Iron Blast Furnace Slag

AS 3582.3 Supplementary Cementitious Materials for use with Portland and

Blended Cement - Silica Fume

ASTM A615 Standard Specification for Deformed and Plain Billet Steel Bars for

Concrete Reinforcement

ASTM A185 Standard Specification for Steel Welded Wire Fabric, Plain, for

Concrete Reinforcement

ASTM A82 Standard Specification for Steel Wire, Plain, for Concrete

Reinforcement

ASTM 416-96 Standard Specification for Steel Strand, Uncoated Seven-Wire for

Prestressed Concrete

ASTM A722-97 Standard Specification for Uncoated High-Strength Steel Bar for

Prestressing Concrete.

ASTM A882/A882M-96 Standard Specification for Epoxy-Coated Seven-Wire

Prestressing Steel Strand.

ASTM A886/A886M-96 Standard specification for Steel Strand, Indented, Seven-Wire

Stress-Relieved for Prestressed Concrete.

ASTM C150 Standard Specification for Portland Cement Type I would also be

acceptable.

ASTM C595M Standard Specification for Blended Hydraulic Cements (Metric)

ASTM C618 Standard Specification for coal Fly Ash and Raw or Calcined Natural

Pozzolan for Use as a Mineral Admixture in Concrete

ASTM C989 Standard Specification for Ground Granulated Blast Furnace Slag

for Use in Concrete and Mortars

ASTM C1240 Standard specification for Silica Fume for Use as a Mineral Admixture in

Hydraulic Cement, Concrete, Mortar and Grout ASTM C33 Standard Specification for Concrete Aggregates

ASTM C494 Standard Specification for Chemical Admixtures in Concrete

ASTM C260 Standard Specification for Air-entraining Admixtures of Concrete

ASTM C1017 Standard Specification for Chemical Admixtures for Use in Producing

Flowing Concrete.”

The following Australian Standards referred to in Section 5 have been withdrawn:

AS1312

AS 1314


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SECTION 6 STEEL AND COMPOSITE

CONSTRUCTION

6.2 Materials

6.2.1 Yield Stress and Tensile Stress used in Design.

Add the following new Article after 6.2.1.1:

“6.2.1.3 Equivalent ASTM Standards

The revised Table 6.2.1 includes nearest, but not exact, equivalent ASTM Standards

and Grades. An exact equivalent is not possible to specify as there is sometimes none

available or because part of the standard complies, but other part may not (eg the

range of thicknesses).

In critical cases both standards (AS and ASTM) should be compared and the

designer should establish the full compatibility of the ASTM Standard for the intended

use.

Table 6.2.1 Strength of Steels Complying wi th AS 1163, AS 1594, AS

3678 and AS 3679.

Steel

Standard

Form Steel Grade Thickness

of material

(t), (mm)

Yield

Stress

(MPa)

Tensile

Strength

(MPa)

ASTM

No.

ASTM

Grade

C450 All 450 500

C450 L0 All 450 500

C350

C350L0

All 350 430

AS 1163 Hollow Sections

C250

C250L0

All 250 320

Plate & Strip XF500 All 480

(see

Note)

570 A715 Gr 70

Plate, Strip &

Floorplate

Hd400 All 400 460 A572 Gr 60

t ≤ 3.5 380 460 A715 Gr 60 Plate & Strip XF400

t > 3.5 360 440 A715 Gr 60

Plate, Strip &Floorplate

Hd350 All 350 430 A572 Gr 50

Plate & Strip HW350 All 340 450 A606

Hd300/1 All 300 430 A414 Gr BPlate, Strip &

FloorplateHd300 All 300 400 A572 Gr 42

Plate & Strip XF300 All 300 440 A715 Gr 50

Hd250 All 250 350 A36

AS 1594

Plate, Strip &

FloorplateHd200 All 200 300 A570 Gr 30


39/67




Table 6.2.1 (Continued)

Steel

Standard


of material

(t), (mm)

Yield

Stress

(MPa)

Tensile

Strength

(MPa)

ASTM

No.

ASTM

Grade

400

400L15

t ≤ 12 400 480 A572 Gr 60

400

400L15

12


40/67




Steel

Standard


of material

(t), (mm)

Yield

Stress

(MPa)

Tensile

Strength

(MPa)

ASTM

No.

ASTM

Grade

250

250L0

250L15

t ≤ 12 260 410 A 36

250250L0

250L15

12 < t < 40 250 410 A 36


41/67




Table 6.2.1 (Continued)

Steel

Standard


of material

(t), (mm)

Yield

Stress

(MPa)

Tensile

Strength

(MPa)

ASTM

No.

ASTM

Grade

AS 3679 Sections & Flat

bars (cont.)

250

250L0250L15

t ≥ 40 230 410 A 36

350

350L0

350L15

t ≤ 50 340 480 A 572 Gr 50

350

350LO

350L15

50


42/67




SECTION 7 RATING

There are no amendments to Section 7.

RAILWAY SUPPLEMENT TO SECTIONS 1-5

1.1 General Principles

1.1.1 Applicability

In the first line replace “Australia” with “Cambodia”.


43/67

RBHraCaNacRkkm


44/67


AMENDMENTS TO BASE DOCUMENT BRIDGE DESIGN COMMENTARY

July 1999 MINISTRY OF PUBLIC WORKS AND TRANSPORT

BLANK


45/67


BRIDGE DESIGN COMMENTARY AMENDMENTS TO BASE DOCUMENT

MINISTRY OF PUBLIC WORKS AND TRANSPORTJuly 1999 Page 3 of 25

TABLE OF CONTENTS

SECTION C1 - GENERAL

C1.1 General Principles. ........... ........... ......... .......... ........... .......... . ....... ....... ...... ...5

C1.1.1 Applicability ....................................................................................5

C1.3 Geometric Requirements - Carriageway Widths and Vertical Clearances. .... ... ..5C1.3.1 Bridge Carriageway Widths........... ........... .......... ....... ....... ....... ....... ...5

C1.3.2 Edge Clearances for Bridges Without Footways .......... ........... ........... .5

SECTION C2 - LOADS

C2.3 Traffic Loading ........... ........... .......... ........... ........... .......... ........ ....... ........ ......5

C2.3.3 L44 Lane Loading ........... ........... .......... .......... ........... ........... ............ 5

C2.3.4 Heavy Load Platform Loading.................... .......... ... ....... ....... ....... ......5

C2.3.5 Number of Lanes for Design and Lateral Position of Loads. .... ... .... ... ... .6

C2.3.5.2 Heavy load platform loading................... .......... .... .... ...6

C2.3.8 Fatigue Loading............ ........... ......... .......... ........... ........... ...... ...... ...6

C2.4 Dynamic Load Allowance...... ........... ........... ..... .......... ........... ........... ............ 6

C2.4.1 General...........................................................................................6

C2.4.2 Dynamic Load Allowance - T44 Truck and L 44 Lane Loadings.... .... ... ..6

C2.5 Horizontal Forces Due to Traffic ........... ........... .......... ........... ........... .......... ....7C2.5.2 Braking forces .......... ........... ........... ........... ........... .......... ........ ....... ..7

C2.5.4 Minimum Lateral Restraint Capacity - Ultimate Limit State ....... ....... ....7

C2.8 Wind Loads ................................................................................................8

C2.8.2 Basic Wind Speeds .......... ........... ........... .......... ........... ........... ....... ..8

C2.8.2.3 Terrain and structure height multipliers, and... ... .... .... ...8

C2.8.2.4 Changes in terrain category. .......... ........... ........... ..... .8

C2.9 Thermal Effects...... ........... ........... .... .......... .......... ........... . ....... ....... ....... ......8

C2.9.2 Variation in Average Bridge Temperature.......... ........... ........... ............ 8

C2.9.3 Differential Temperature........... ........... .......... ........... ........... .......... .. 10

C2.13 Earthquake Forces... ........... .......... ........ .......... .......... ........... . ............. ....... 10

C2.13.1 General.........................................................................................10

C2.13.2 Earthquake Resistant Design.......... ........... .......... . ........ ....... ....... .... 10

C2.13.4 Equivalent Quasi-Static Earthquake Forces........... ........... ........... ..... 11C2.19.3 Design Wind Speeds ..................................................................... 12

C2.19.3.2 Ultimate limit state.............. ........... ....... ...... ....... ..... 12

SECTION C3 - FOUNDATIONS .......... ........... ........... .......... ........... ........... ............ 13

SECTION C4 - BEARINGS AND DECK JOINTS

C4.3 Loads and Movements.... ........... ........... ....... .......... ........... ........... ...... ....... . 13

C4.14 Deck Joints...............................................................................................13

C4.14.7 Proprietary Deck joints.......... ........... ........... .......... ........... ........... ... 13

SECTION C5 - CONCRETE

C5.1 Scope and General .......... ........... ........... .......... .......... ........... . ............. ....... 14

C5.1.1 Scope and Application .......... ........... ........... .......... ........... ........... ... 14

C5.1.1.2 Application............................................................. 14

C5.1.5 Construction..................................................................................14

C5.2 Design Requirements and Procedures........ ........... .......... ... ........ ........ ....... .. 15

C5.2.4 Design for Serviceability ........... ........... .......... ........... .......... ........... . 15

C5.2.4.3 Cracking ................................................................ 15

C5.2 Design for Durability................. ........... .... ........... ........... .......... ...... ....... ......16

C5.4.3 Exposure Classification..................... ........... . ........... .......... ........... . 16

C5.4.10 Requirements for Cover to Reinforcing Steel and Tendons..... .... .... ... .. 17

C5.4.10.3 Cover for Corrosion Protection......... ........... ........... . .. 17

C5.6 Design Properties and Materials ........... ........... .......... ........... .......... ........... . 17

C5.6.1 Properties of Concrete............ ........... ......... .......... ........... ........... .... 17

C5.6.1.7 Shrinkage and ........... ........... .......... ............ ............ 17


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C5.7.1.8 Creep.....................................................................17

C5.6.2 Properties of Reinforcement ........... ........... .......... ........... ........... ...... 18

C5.6.2.1 Strength .................................................................18

C5.6.3 Properties of Tendons.... ........... ........... ....... .......... ........... ........... ....18

C5.8.6 Crack Control of Beams........ ........... ........... .. .......... ........... .......... . ..18

C5.13 Stress Development and Splicing of Reinforcement and Tendons. ... .... ... .... ... .19

C5.13.1 Stress Development in Reinforcement...... .......... ........... ..... ....... ...... .19C5.13.1.2 Development length of bar in tension. ............ ............ 19

C5.16 Material Requirements .......... ........... .......... . ........... ........... .......... ...... ...... ...20

C5.16.1 Material Requirements for Concrete and Grout. .......... ........... ........... .20

C5.16.2 Material for Reinforcing Steel............ ........... ......... ....... ...... ....... .......20

C5.16.3 Material Requirements for Prestressing Ducts, Anchorages and

Tendons........................................................................................21

C5.16.3.2 Anchorages. ........... .......... ........... ....... ...... ....... .......21

C5.16.3.4 Tendons ........... ........... .......... .......... ........... ........... .21

SECTION C6 - STEEL AND COMPOSITE CONSTRUCTION

C6.2 Materials...................................................................................................21

C6.2.1 Yield Stress and Tensile Stress used in Design .......... ........... ........... 21

C6.2.1.3 Equivalent ASTM Standards .......... ........... ........... .....21

SECTION C7- RATING

C7.7 SUPPORTING INFORMATION. .......... ........... ........... .......... ........... ........... ...21

C7.7.1 Publications ..................................................................................21

C7.7.2 Other Information .......... ........... ........... .......... .......... ........... . ...... .....22

RAILWAY SUPPLEMENT TO SECTIONS C1-5

SECTION C2 - DESIGN LOADS

C2.3 Traffic Loading........... ........... .......... .......... ........... ........... ....... ....... ....... .....23

C2.3.12 300-A-12 Railway Traffic Loading. .......... ........... .......... ........ ....... ......23

APPENDIX A

NAASRA BRIDGE DESIGN SPECIFICATION 1976 - SECTION 3 - LOAD DISTRIBUTION .25


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SECTION C1 - GENERAL

C1.1 General Principles

C1.1.1 Applicability

The range of bridges for which the ‘92 AUSTROADS Code is applicable has been

extended to include railway bridges; Clause 1.1.1 of the Railway Supplement refers.

The provisions of Clause 1.1.1. have been extended for the use by the Ministry of

Public Works and Transport and also for use by any other Authority or organisation.

C1.3 Geometric Requirements - Carriageway Widths and

Vertical Clearances.

C1.3.1 Bridge Carriageway Widths

The minimum set back distance of the kerb on bridge has been adjusted to suit the other

adopted horizontal clearances.

C1.3.2 Edge Clearances for Bridges Without Footways

The edge clearances on bridges without footways have been coordinated with values

included in the Road Design Manual.

SECTION C2 - LOADS

C2.3 Traffic Loading

C2.3.3 L44 Lane Loading

Replace the second paragraph with the following:

“L 44 has been slightly modified at the request of Cambodian Authorities.

The tandem of concentrated loads is not intended to represent heavy axles, but it is

merely an analytical device used to simulate the bending and shearing effectscaused by actual vehicle loading”.

C2.3.4 Heavy Load Platform Loading.

Replace the second paragraph with the following:


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“The application of HLP 240 is mandatory for all bridges on Expressways,

Highways, Provincial Roads, Secondary Roads and Arterial roads. For bridges on

other roads it is not mandatory. However, the Authority should consider:“

C2.3.5 Number of Lanes for Design and Lateral Position ofLoads.

C2.3.5.2 Heavy load platform loading.

This Clause has been only amended to include the HLP 240. The Authority may specify

other special HLP loading on specially designated roads.

C2.3.8 Fatigue Loading

No additional commentary is provided.

C2.4 Dynamic Load Allowance.

C2.4.1 General

Replace the last two sentences (commencing with ‘Because…) with the following:

“The constant dynamic load allowance for T44 and L44 loadings for all span

lengths is based on the AASHTO approach and its magnitude is broadly that

corresponding to dynamic responses of short and medium span bridges. Longer

span bridges normally have low first flexural frequencies and therefore lowerdynamic load allowances may be applicable. However, with increasing length of

span the ratio of live load to dead load is decreasing and therefore the ratio of the

dynamic load allowance to the total load is also decreasing. In addition, the CBDS

also provides for alternative determination of the dynamic load allowance.”

C2.4.2 Dynamic Load Allowance - T44 Truck and L 44 LaneLoadings

The dynamic load allowance expressed as a constant percentage of the live load has been adopted for simplicity, instead of the method included in the 1992 AUSTROADS

Bridge Design Code, which requires to use an approximate value for the design and re-check the adopted value when all the information for calculation of first flexural

frequency is available.

To achieve optimum economy for major structures and/or long spans, the Authority mayapprove different values of dynamic load allowances based on tests or dynamic analysis.


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C2.5 Horizontal Forces Due to Traffic

C2.5.2 Braking forces

The braking forces between 400 kN and 800 kN specified by the AUSTROADS

Bridge Design Code have been reduced to between 300 kN for short bridges and

600 kN for bridges 60 m and longer. Road trains with overall weight exceeding 100 t

and travelling at high speed are not considered to be applicable in foreseeable future for

Cambodian roads.

Magnitudes of the braking forces adopted for the Cambodian Bridge Design Code,

although lower than the AUSTROADS values, are similar to the braking forces (at

Ultimate Limit State) specified by the British Code and are somewhat higher,

particularly for longer bridges, than the braking forces specified at ULS by AASHTO

and Ontario Codes for up to 3 lanes travelling in the same direction.

C2.5.4 Minimum Lateral Restraint Capacity - Ultimate Limit State

Additional Commentary on the revision of the paragraph 3:

“The Australian Bridge Design Code Clause 2.5.4 specifies some minimum lateral

restraint loadings where no other loading is specified. The minimum of 500 kN is

well in excess of many of the normal loadings which would apply. In particular, in

the case of small bridges over creeks, the likely log impact loadings in the order of

100 kN are overwhelmed by this 500kN ultimate load. Where there is no vehicularaccess under the bridge, there is no good reasons for such a large load as 500 kN.

The bridge needs to be restrained to cater for unanticipated loadings such as

earthquake loadings in a nil earthquake zone, and impact from repair equipment or

other accidental minor impacts. There is no need to have a load as high as 500 kN

for this purpose.

However, a minimum 500 kN load should be retained for all cases where the deck

may be struck by road, rail or river traffic. A 3.5 metre clearance above the normal

vehicle or vessel height provides sufficient assurance to minimise the risk of impact

to a bridge from an anticipated high load.

The revision of the Clause 2.5.4 is based on the amendment document CBE 98/11

issued by the Chief Bridge Engineer of the Roads and Traffic Authority of NSW

authorised for use from 30 July, 1998.”


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C2.8 Wind Loads

C2.8.2 Basic Wind Speeds

Replace the part of the last paragraph commencing with “The current...” with the

following:

“The appropriate Serviceability Limit State basic gust design wind speeds have

been determined from the data provided by the Department of Meteorology inPochentong, Phnom Penh, the undated French report ‘Apercu General sur le

Climat du Cambodge’ and other sources. In Cambodian conditions the

Serviceability Limit State design wind speed is uniform at 35 m/sec and the

Ultimate Limit State wind speeds vary between 45 m/sec inland and 60 m/sec in

the coastal region close to the coast. Table 2.8.2 replaces references to the

AS 1170.2.

Structural importance and shielding factors have been omitted. Use of these factorsin the AUSTROADS Bridge Design Code is reflecting the origin of these

provisions in the AS 1170.2 which is a wind loading code for all types of

structures. For bridges the relevance of these factors is not significant.”

C2.8.2.3 Terrain and structure height multipliers, and

C2.8.2.4 Changes in terrain category.

The values in these clauses have been updated in accordance with the draft of the new

edition of the AS 1170.2.

C2.9 Thermal Effects

C2.9.2 Variation in Average Bridge Temperature

For Cambodia, the Minimum, Maximum and Average Shade Air Temperatures have

been derived from the information contained in the undated French Report ‘Apercu

General sur le Climat du Cambodge’ as follows:


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Station Av.

Annual

max.

temp.

(º C)

Average

annual

min.

temp.

(º C)

Average

annual

temp.

(º C)

Absolute

min. (º C)

Absolute

max. (ºC)

Derived

from a

period of

Climatic

Region

Stung Treng 31.6 22.6 27.1 9.5 41.4 28 years H

Siem Riap 32.0 22.7 27.4 9.5 40.3 28 years F

Battambang 32.5 23.0 27.7 10.4 41.0 20 years F

Krakor 32.2 23.1 27.7 14.6 39.5 5 years F

Kompong

Cham

(Chhnang)

32.0 23.4 27.7 12.4 39.3 26 years F

Pochentong

(Phnom

Penh)

32.2 23.7 27.8 13.3 40.5 42 years F

Svay Rieng 32.5 23.4 27.9 12.2 38.7 24 years F

Kampot 31.2 23.6 27.4 14.7 37.2 18 years C

Sihanoukville 30.3 25.2 27.8 20.5 34.4 4 years C

The altitudes of all stations but Stung Treng is


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This information indicates remarkable uniformity of average annual temperatures across

the country. The most appropriate temperature for the determination of nominal

dimensions dependant on temperatures (ie for setting of deck openings at deck

expansion joints, etc.) would appear to be 27 ºC.

The stations are located in all three climatic zones (Coastal, Flat Lands, High Lands),however, there is only one station located in the High Land Climatic region. The

elevation of this station is only 54 m and it is therefore not representative for the

mountainous north eastern region of Cambodia. No climatic information appears to be

available for this region and the recommended temperature reductions related to high

elevations are based on information from other tropical regions.

C2.9.3 Differential Temperature

Values of T have been revised to reflect the climatic conditions prevailing in Cambodia,

namely, higher uniformity of temperatures than in Australia.

In the absence of information on temperature ranges in higher elevations in Cambodia,

the value of T has been determined from information from other tropical regions.

C2.13 Earthquake Forces

C2.13.1 General

Replace the text with the following:

“Earthquake severity at different locations is now defined by an acceleration

coefficient, a, the value of which for Cambodia has been determined by the

Seismological Centre of the Australian Geological Survey Organisation inCanberra, on the basis of the World Earthquake Database. This indicates that

there is not a single epicentre in Cambodia. Figure C2.13.1, a copy of the map of

regional seismicity covering Cambodia and a large area around Cambodia, shows

the regional tectonics.

The ISC World Seismograph station list shows that there are no seismographs inCambodia. The records also show that there have been no magnitude 6+

earthquakes since 1960 and no magnitude 5+ earthquakes since 1980. The nearest

large earthquake was more than 300 km from the Cambodian border and the plate

boundaries at least 650 km away.”

C2.13.2 Earthquake Resistant Design

Delete second paragraph and replace with the following:

“In a general situation, design for earthquake resistance must comprise anassessment of the seismicity of the site, an estimation of the induced seismic load


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and an evaluation of the structural system characteristics and the dynamic structural

response. The subject is discussed in Newmark and Rosenbleuth (1971).

Evaluation of the dynamic response due to seismic loading of a specified

acceleration spectrum can be performed with the aid of a number of readily

available computer programs.”

F igur e C2.13.1 Map of Regional Seismicity

C2.13.4 Equivalent Quasi-Static Earthquake Forces.

Delete fourth paragraph and replace with the following:

“The seismicity Factor, α , has been related to the acceleration coefficient, a.”

Delete sixth paragraph and replace with the following:


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Page 12 of 25 July 1999 MINISTRY OF PUBLIC WORKS AND TRANS

Cambodia Bridge Design Standard

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