t02 Austroads Loadings

Sinclair Knight Merz, Infratech Systems & Services, Road User Research

LOADING CODEContents Summary

2.1 General ...........................................................................................................1

2.2 Dead Loads ....................................................................................................1

2.3 Traffic Loads..................................................................................................1

2.4 Not used .........................................................................................................6

2.5 Not used .........................................................................................................6

2.6 Collision Loads on Bridge Supports...........................................................6

2.7 Kerb and Barrier Design Loadings..............................................................6

2.8 Wind Loads....................................................................................................6

2.9 Thermal Effects .............................................................................................6

2.10 Forces Due to Water .....................................................................................6

2.11 Earth Pressure...............................................................................................6

2.12 Friction Forces ..............................................................................................6

2.13 Earthquake Forces ........................................................................................6

2.14 Shrinkage, Creep and Prestress Effects .....................................................6

2.15 Differential Movement of Supports .............................................................6

2.16 Construction Forces and Effects.................................................................6

2.17 Load Combinations.......................................................................................6

2.18 Dynamic Behaviour.......................................................................................6

2.19 Road Signs & Lighting Structures...............................................................6


Loading Code Contents Details2.1 General ...........................................................................................................1

2.2 Dead Loads ....................................................................................................1

2.3 Traffic Loads..................................................................................................12.3.1 General...............................................................................................12.3.2 W80 Wheel Loading...........................................................................22.3.3 A160 Axle Loading .............................................................................22.3.4 M1600 Moving Traffic Loading ...........................................................22.3.5 S1600 Stationary Traffic Loading .......................................................22.3.6 Heavy Load Platforms ........................................................................22.3.7 Number of Lanes for Design and Lateral Position of Loads...............32.3.8 Accompanying Lane Factors for Multiple Lane Bridges .....................32.3.9 Centrifugal Forces ..............................................................................32.3.10 Braking Forces ...................................................................................42.3.11 Dynamic Load Allowance (DLA).........................................................4

2.3.11.1 Magnitude of the Dynamic Load Allowance .............................42.3.11.2 Application of the Dynamic Load Allowance ............................4

2.3.12 Fatigue Loading..................................................................................52.3.13 Pedestrian Loading.............................................................................52.3.14 Tramway and Railway Loading...........................................................52.3.15 Load Factors and Combinations of Traffic Loadings..........................52.3.16 Minimum Lateral Force.......................................................................5

2.4 Not used .........................................................................................................6

2.5 Not used .........................................................................................................6

2.6 Collision Loads on Bridge Supports...........................................................6

2.7 Kerb and Barrier Design Loadings..............................................................6

2.8 Wind Loads....................................................................................................6

2.9 Thermal Effects .............................................................................................6

2.10 Forces Due to Water .....................................................................................6

2.11 Earth Pressure...............................................................................................6

2.12 Friction Forces ..............................................................................................6

2.13 Earthquake Forces ........................................................................................6

2.14 Shrinkage, Creep and Prestress Effects .....................................................6

2.15 Differential Movement of Supports .............................................................6

2.16 Construction Forces and Effects.................................................................6

2.17 Load Combinations.......................................................................................6


2.18 Dynamic Behaviour.......................................................................................6

2.19 Road Signs & Lighting Structures...............................................................6

1Sinclair Knight Merz, Infratech Systems & Services, Road User Research

2 Design Loads2.1 General

Structures shall be proportioned for the designloads, forces and effects when they exist as setout in Articles 2.2 to 2.16.

If the Authority approves, the design engineer mayvary any of the loads set out in this section on thebasis of engineering measurement andcalculations, provided the loads comply with thegeneral principles of design as set out inSection 1.

The design loads and forces shall be consideredas acting in combinations as set out in Article2.17.

The design engineer shall consider each individualbridge to assess whether any other loads, forcesor effects are applicable to that particular design.The magnitude of these additional forces oreffects and their combination with other loads shallbe consistent with the principles set out in Section1.

On the front sheet of the bridge drawings, thefollowing details relating to design loads must beshown where relevant:

the edition of the Code used any significant variation to the minimum

design loads set out in this Section traffic load (W80, A160, M1600, S1600 The

abbreviation MS1600 implies that the bridgehas been designed to resist the W80, A160,M1600 and S1600 loads)

collision load on piers where applicable design wind speeds flood data (design velocities, levels, debris

etc) earthquake zone differential settlements and mining

subsidence effects allowed for in design foundation data where not shown

elsewhere.

Where required by design conditions, theconstruction methods and sequence or any otherspecific limitations shall be indicated on the bridgedrawings.

2.2 Dead Loads

no change required

2.3 Traffic Loads

2.3.1 General

Traffic loading is the loading resulting from thepassage of vehicles (either singly or in groups) orpedestrians. The magnitude, direction andpositioning of loads specified in this Code produceeffects in structures that approximate the effectsof vehicles or groups of vehicles. The load modelsare not intended to be the same as actualvehicles.

All road bridges shall be designed to resist thetraffic loads specified in this Code whichapproximate the effects induced by moving traffic,stationary queues of traffic, accelerating ordecelerating traffic and pedestrian traffic. All roadbridges shall be designed for the most adverseeffects induced by the following loading elements,combinations of these elements and theircorresponding load factors:

W80 Wheel Load A160 Axle Load M1600 Moving Traffic Load S1600 Stationary Traffic Load Dynamic Load Allowance (DLA) Number and position of traffic lanes Accompanying Load Factors (ALF) Centrifugal Forces (FC) Braking Forces (FBS, FBM) Fatigue Loading Pedestrian Loading

2 AUSTROADS Bridge Design Code


2.3.2 W80 Wheel Loading

The W80 wheel loading models an individualheavy wheel load. It shall consist of an 80 kN loaduniformly distributed over a contact area of400 mm x 250 mm. The W80 Wheel loading is tobe applied anywhere on the roadway surface.

2.3.3 A160 Axle Loading

The A160 Axle loading models an individual heavyaxle. It shall consist of the loading shown in Figure2.3.1.

160 kN

400 mm

250 mm

2.0 m

ELEVATION

PLAN

3 m standard design lane

Figure 2.3.1 A160 Axle Load

2.3.4 M1600 Moving Traffic Loading

The M1600 Moving Traffic Load models the loadsapplied by a moving stream of traffic. It is to beconsidered in association with centrifugal forcesand braking forces and is thus relevant for bridgesof all spans.

The M1600 Moving Traffic Load shall consist of auniformly distributed load together with a truckloading as defined in Figure 2.3.2. The uniformlydistributed component of the M1600 Moving TrafficLoad continues under the truck and shall be

considered as uniformly distributed over the widthof a 3 m Standard Design Lane.

The uniformly distributed component of the M1600Moving traffic Load shall be continuous ordiscontinuous and of any length as may benecessary to produce the most adverse effects.Likewise, the truck position and variable spacingshall be determined so as to produce the mostadverse effects.

2.3.5 S1600 Stationary Traffic Loading

The S1600 loading models the loads applied by astationary queue of traffic. The S1600 StationaryTraffic Load shall consist of a uniformly distributedload together with a truck loading as defined inFigure 2.3.3. The uniformly distributed componentof the S1600 Stationary Traffic Load continuesunder the truck and shall be considered asuniformly distributed over the width of a 3 mStandard Design Lane.

The uniformly distributed component of the S1600Stationary Traffic Load shall be continuous ordiscontinuous and of any length as may benecessary to produce the most adverse effects.Likewise the truck position and variable spacingshall be determined so as to produce the mostadverse effects.

2.3.6 Heavy Load Platforms

No heavy load platform design loading (HLP) isrequired unless specified by the Authority.

360 kN 360 kN 360 kN 360 kN

ELEVATION

6 kN/m

3.5 m Varies: 6.5 m minimum 5.0 m

0.5 m

2.0 m

0.5 m

400 mm200 mm 3 m standard

design

PLAN

1.25 1.25 1.25 1.25 1.25 1.25 1.25 1.25

Figure 2.3.2 M1600 Moving Traffic Load

2 - Design Loads 3


2.3.7 Number of Lanes for Design andLateral Position of Loads

The A160, M1600 and S1600 loadings shall beassumed to occupy one Standard Design Lane of3 m width. The number and position of StandardDesign Lanes shall be as follows:

The number of Standard Design Lanes n shall be:

13.bn = (rounded down to next integer)

where b = width between traffic barriers (inmetres) unless specified otherwise.

These Standard Design Lanes shall be positionedlaterally on the bridge to produce the mostadverse effects.

2.3.8 Accompanying Lane Factors forMultiple Lane Bridges

When more than one lane is loaded, the A160,M1600 or S1600 loading applied to the additionallanes shall be multiplied by the AccompanyingLane Factors in Table 2.3.8.

The number of Standard Design Lanes loadedand the load patterning (Standard Design Lane

numbering) is to be selected to produce the mostadverse effects.

For bridges that support vehicle and pedestriantraffic, the accompanying lane factors shall beapplied to both the vehicle and the pedestriantraffic. The total pedestrian loading shall beconsidered as one Standard Design Lane.

2.3.9 Centrifugal Forces

For bridges on horizontal curves, allowance shallbe made for the centrifugal effects of trafficloading on all parts of the structure. The bridge isto be designed to resist the most adverse co-existing effects induced by the M1600 MovingTraffic Load and the Centrifugal Force (FC).

The Centrifugal Force (FC) shall be assumed toact at deck level and is to be applied inaccordance with the distribution of load in theM1600 Moving Traffic Load. The Centrifugal Force(FC) shall be calculated from:

C

CC

W

WrgvF

).( than greater not but +

=

350

2

whereFC = centrifugal force (kN)WC = the load due to the M1600 Moving

Traffic Load for the length underconsideration (kN). Accompanyinglane factors shall be applied. NoDynamic Load Allowance is to be

considered. (ie. = =

j

iii MALF

1

1600 )

v = operating speed of the road (m/s)r = radius of curve (m)g = acceleration due to gravity

(9.81 m/s2) = super-elevation of the road

expressed as a ratio

240 kN 240 kN 240 kN 240 kN

ELEVATION

24 kN/m

1.25 3.5 m Varies: 6.5 m minimum 5.0 m

0.5 m

2.0 m

0.5 m

400 mm200 mm 3 m standard

design

PLAN

1.25 1.25 1.25 1.25 1.25 1.25 1.25

Figure 2.3.3 S1600 Stationary Traffic Load

Table 2.3.8 Accompanying lane factors

Standard DesignLane Number ( i )

Accompanying LaneFactor (ALFi)

1 1.0

2 0.8

3 or more 0.4



2.3.10 Braking Forces

Braking effects of traffic shall be considered as alongitudinal force. Braking forces shall be appliedin either direction. The restraint system shall bedesigned to resist the most adverse co-existingeffects induced by the Braking Force (FB) and thevertical traffic loading. The Braking Force (FB) is tobe applied in accordance with the distribution ofmass of the vertical traffic loading.

The braking force (FB) shall be assumed to act atthe road surface. The most adverse effects fromthe following two scenarios (FBS and FBM) shall beconsidered:

(a) Single vehicle stopping

FBS = 0.45WBS but not less than 200 kN orgreater than 700 kN

Where:FBS = braking force applied by a single

vehicle (kN)WBS = load due to a single lane of the

M1600 Moving Traffic Loading up to amaximum of 1600 kN (i.e. 25 m ofM1600 loading).

(b) Multi-lane moving traffic stream stopping

FBM = 0.15WBM

whereFBM = braking force applied by multiple

vehicles (kN)WBM = the load due to multiple lanes of the

M1600 Moving Lane Load for thelength under consideration (kN).Accompanying lane factors shall be

applied (i.e = =

j

iii MALF

1

1600 ).

When assessing the effects of longitudinal forceson bridge bearings and substructure, the friction orshear displacement characteristics of expansionbearings and the stiffness of the substructure shallbe taken into account.

2.3.11 Dynamic Load Allowance (DLA)

The dynamic load allowance (DLA) models thedynamic effects of vehicles moving over bridgeswith typical road profile irregularities.

2.3.11.1 Magnitude of the Dynamic LoadAllowance

The maximum bridge response = (1+ DLA) x themaximum static bridge response to the loadingunder consideration. The DLA is set out in Table2.3.1.

Table 2.3.1 Dynamic Load Allowance

Note: No Dynamic Load Allowance (DLA) is required forCentrifugal Forces, Braking Forces or Pedestrian Loadings.

0.00

0.10

0.20

0.30

0.40

0.50

0 1 2 3 4 5 6 7First flexural frequency of the superstructure (Hz)

Dyn

amic

load

allo

wan

ce

Note: A range of first flexural frequencies from 0.9 to 1.1times the calculated superstructure frequency shall be

considered. The dynamic load allowance adopted shall be themaximum value obtained from this figure for this frequency

range.

Figure 2.3.4 Dynamic Load Allowance for M1600Moving Traffic Load

2.3.11.2 Application of the Dynamic LoadAllowance

The dynamic load allowance shall be applied to allparts of the structure extending down to theground line.

For parts of the structure below the ground line,the Dynamic Load Allowance shall be linearlytransitioned from the ground line value to zero at acover depth of 2 m.

For buried structures, such as culverts and soil-steel structures, the Dynamic Load Allowance

Loading Dynamic LoadAllowance (DLA)

W80 Wheel Load 0.3

A160 Axle Load 0.3

M1600 Moving TrafficLoad

As perFigure 2.3.4

S1600 Stationary TrafficLoad

0.0

2 - Design Loads 5


shall not be less than the values specified for theA160 Axle Load (applied to the W80 Wheel Load,the A160 Axle Load and M1600 Moving TrafficLoad) for a cover depth of zero and not less than0.1 for a cover depth of 2 m or more, with a linearinterpolation in between. The Dynamic LoadAllowance established for the appropriate coverdepth shall apply to the complete structure.

2.3.12 Fatigue Loading

Amendments to this section are to be prepared bythe Austroads Structures Technology Group sothat the fatigue loads are compatible with therevised Traffic Loads.

2.3.13 Pedestrian Loading

No change

2.3.14 Tramway and Railway Loading

The implications of and for the newAUSTROADS Railway Supplement needconsideration.

2.3.15 Load Factors and Combinations ofTraffic Loadings

The effects of the elements of the transient trafficloads defined in this Article are to be combined inthe following manner to achieve the most adverseresults. These combined traffic loads are thencombined with other loads as specified in Article2.17.

In the following definitions, the subscript i is thestandard design lane number which varies from 1to the number of standard design lanes n. Thenumber of lanes loaded ( j ) and the sequence inwhich the lanes are numbered is to be chosen toinduce the most adverse effects.

The effects of pedestrian loads are to be added tothe A160, M1600 and S1600 loads whereapplicable.

(a) Serviceability Limit State

)1(80 DLAW +

)+(11601=

j

iii DLAAALF

=

j

iii DLAMALF

11600 )+(1

=

j

iiiALF

1 S1600

=

j

iiiC DLAALFF

1

)+(1M1600 and

)1(1600 and 1 DLAMFBS +

)1(1600 and 1

DLAMALFFj

iiiBM +

=

(b) Ultimate Limit State

[ ])(. DLAW + 18081

=

)+(1.j

iii DLAAALF

1

16081

=

j

iii +DLAMALF

1116008.1 )(

=

j

iii SALF

1

160081 .

=

j

iiiC +DLAMALFF

1116008.1 )( and

[ ])( and DLA MFBS + 116008.1 1

+

=

)( and DLAMALFFj

iiiBM 116008.1

1

Note that the lateral forces shall not be less thanthe Minimum Lateral Restraint force defined inArticle 2.3.16.

2.3.16 Minimum Lateral Force

To ensure that the superstructure has sufficientlateral restraint to resist unaccounted for lateralforces not otherwise accounted for in the design, apositive lateral restraint system between thesuperstructure and the substructure shall beprovided at piers and abutments.

For continuous superstructures, lateral restraintsmay be omitted at some piers provided eachcontinuous section of superstructure betweenexpansion joints is adequately restrained.

The restraint system for each continuous sectionof superstructure shall be capable of resisting anultimate design horizontal force normal to thebridge centreline of 500 kN or 5% of the



superstructure dead load at that support,whichever is greater.

Supports providing this lateral restraint shall alsobe designed to resist this design force at theUltimate Limit State.

Restraints shall have sufficient lateral clearance toallow thermal movements, especially on widecurved superstructures.

2.4 Not used

Not used

2.5 Not used

Not used

2.6 Collision Loads on BridgeSupports

Amendments to this section are to be prepared bythe Austroads Structures Technology Group sothat the loads are compatible with the revisedTraffic Loads.

2.7 Kerb and Barrier DesignLoadings

Amendments to this section are to be prepared bythe Austroads Structures Technology Group sothat the loads are compatible with the revisedTraffic Loads.

2.8 Wind Loads

As per Australian Bridge Design Code.

2.9 Thermal Effects


2.10Forces Due to Water


2.11Earth Pressure


2.12Friction Forces


2.13Earthquake Forces


2.14Shrinkage, Creep andPrestress Effects


2.15Differential Movement ofSupports


2.16Construction Forces andEffects


2.17Load Combinations


2.18Dynamic Behaviour


2.19Road Signs & LightingStructures




Comments by Adam Lim MRD WA

1. Cl 2.3.8 accompanying load factors should be accompanying lane factors (refers to pedestrian loads)

2. Cl 2.18. Refers to deflection due to T44.

2.1General2.2Dead Loads2.3Traffic Loads2.3.1General2.3.2W80 Wheel Loading2.3.3A160 Axle Loading2.3.4M1600 Moving Traffic Loading2.3.5S1600 Stationary Traffic Loading2.3.6Heavy Load Platforms2.3.7Number of Lanes for Design and Lateral Position of Loads2.3.8Accompanying Lane Factors for Multiple Lane Bridges2.3.9Centrifugal Forces2.3.10Braking Forces2.3.11Dynamic Load Allowance (DLA)2.3.11.1Magnitude of the Dynamic Load Allowance2.3.11.2Application of the Dynamic Load Allowance

2.3.12Fatigue Loading2.3.13Pedestrian Loading2.3.14Tramway and Railway Loading2.3.15Load Factors and Combinations of Traffic Loadings2.3.16Minimum Lateral Force

2.4Not used2.5Not used2.6Collision Loads on Bridge Supports2.7Kerb and Barrier Design Loadings2.8Wind Loads2.9Thermal Effects2.10Forces Due to Water2.11Earth Pressure2.12Friction Forces2.13Earthquake Forces2.14Shrinkage, Creep and Prestress Effects2.15Differential Movement of Supports2.16Construction Forces and Effects2.17Load Combinations2.18Dynamic Behaviour2.19Road Signs & Lighting Structures

t02 Austroads Loadings

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