Ashton Avenue Integral Bridge with

Battledeck Slab

Behzad Golfa| Senior Structural Engineer

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Overview of Ashton Avenue Bridge

Location Ashton Avenue over Perth Fremantle Railway.

Span Length 19.1m between abutments centreline

Bridge Width 20.51 m overall and 12.5 m minimum between kerbs

Span to Depth Ratio 37

Client Main Roads WA

Consultant GHD

Contractor Coleman Rail

Contract Value Approx $ 10 m

•Bridge Location

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Longitudinal Elevation

of Old Bridge

Elevation of Old Bridge

4800

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Project Constraints• Provide increased vertical rail clearances of 5.4m;

• Limited opportunity to raise the road level of Gugeri Street and Ashton

Avenue intersection;

• Constant deck thickness to provide minimum clearance over shared

path;

• Very limited space for foundation works due to constrained corridor;

• Only two weekend rail shutdowns permitted – one for deconstruction of

existing bridge and one for beam placement. All other work to be

completed during normal rail operations.

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Replacement Options

Option 1. The VFT-WIB beam;

• This option required a hunched beam profile which reduced the clearance

on both ends.

• Complex fabrication.

Option 2. Prestressed concrete planks with an in-situ topping slab.

• The difference between short term and long term deflection was more

than the other two options and the pre-camber deflection was excessive.

Option 3. Battledeck Planks;

• Simpler steel fabrication compare to VFT-WIB.

• Provides a constant deck thickness,

• The difference between the long-term and short-term deflection of

battledeck plank was minimum.

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Solution: Integral bridge with battledeck planks

5.4

m

Road level constraint due to

geometry of Gugeri Street and

Ashton Ave intersection.

Min

2.7

m

515mm

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Battledeck Superstructure

The superstructure comprises:

• 20 No. precast battledeck planks.

• 2 No of 310 UC 158 steel beams.

partially encased in reinforced concrete.

• Top and bottom flange shear studs and

shear ties used to ensure composite action.

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Battledeck Superstructure

Advantages:

• The beams acted compositely with concrete in both sagging and hogging area.

• The steel beams were acting compositely with concrete during installation.

• The difference between long term and short term deflections was minimum

compared to concede prestressed bweam.

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Battledeck Geometry Requirement

The battledeck plank geometry was designed

to meet the geometry requirements of

Eurocode 4 for the “filler beams”.

•The steel beams are not curved in plan;

•The skew angle should not be greater than

30°;

•The nominal depth h of the steel beams

complies with: 210 mm<h<1100 mm;

•The spacing Sw of webs of the steel beams

do not exceed the lesser of h/3 + 600 mm and

750 mm.

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Battledeck End Connection

Option 1: Using Shear connectors on steel beam flanges.

Option 2: Using Endplate to provide end fixity.

• Insufficient space at abutment to install sufficient shear stud.

• Planks depth was too shallow, there was not sufficient space to install horizontal shear reinforcement.

• The end plate was clashing with the existing reinforcement.

• The end plate made it more difficult to install horizontal shear reinforcement.

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Option3: Using Macalloy Anchor bolts.

Battledeck End Connection

This option utilises a combination of shear connectors and Macalloy anchor bolts to

transfer the bending moment. The anchor bolts moved the stress concentration away from

the connection joint, hence allowing sufficient room to provide required shear ligatures and

longitudinal reinforcement.

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Battledeck Bending Capacity

The design moment determined by plastic theory:

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Why Integral?

1. Moment Redistribution.

2. Operations and maintenance advantages:

a) Removal of bearing and joints;

b) Lower whole-of-life cost;

c) Improvement of bridge appearance;

d) Superior performance under earthquake loading.

Approx 87% of the bridges less than 100m long in United States have

integral abutments.

Bending Moment Diagram Under

Live Load

329 kNm

492 kN.m

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Design of Integral Bridges

Code Requirements

Location Code/Design Guide

Australia AS5100 (no guidance)

VicRoads BTN 2012/003 (references BA 42/96)

UK BA 42/96 (prior to 2011)

PD 6694-1:2011 Section 9 (2011 onwards)

USA Varies State to State

Restrictions on the Use of Integral Bridges:

Criteria PD6694 Vic RoadsBTN USA (FHWA)

Maximum overall length 70m 70m 100m

Skew 30 30 30

Approach Slab length Not requited 1.5 times abutment

depth and 4m3m or 1.5 times abutment depth

Maximum thermal movement at abutments

20mm 20mm 20mm

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Integral Substructure

Foundation:

• Limited space for piling.

• Two rows of 450 mm diameter bored

pile at 1200 mm centres.

Abutment:

• 700mm thick insitu walls with widening

at top to accommodate the steel beam

fixed connection

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Design of Integral Bridges

Lateral Earth pressure k* (European Method)

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Horizontal pressures on abutments accommodating thermal movements by rotation and/or flexure

Full height abutments on spread footings

• H is the vertical distance from

ground level to the level at which

the abutment is assumed to

rotate.

• d’d is the wall deflection at a depth

H/2 below ground level when the

end of the deck expands a

distance dd.

• C is 20 for foundations on flexible

(unconfined) soils with E<100

MPa; and is 66 for foundations on

rock or soils with E> 1000 Mpa.

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Horizontal earth pressures on end screen and abutment that

accommodate thermal movements by translation without rotation

Semi-integral abutment, Sleeved Pile, and bank Abutment

• H is the height of end

screen.

• d’d is the movement of end

screen at H/2 below

ground level.

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Horizontal earth pressures on abutments founded on piles

(without isolation device)To calculate the soil pressure on piled footing an iterative approach is required.

Earth pressures applied to the back of abutment (expansion case)

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Horizontal earth pressures on abutments founded on piles

(without isolation device)

Earth pressures applied to the front of abutment (contraction case)

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For deriving d’d and H’, the following iterative procedure was used.

• Step 1: The soil pressure behind the abutment was calculated based on the movement

due to maximum expansion of the bridge and assuming H’=H & d’=0.5 d.d

• Step 2: The soil pressure in front of piles was calculated based on the movement due

to maximum bridge expansion and assuming: H’=H & d’=0.1 d.d

.

• Step 3: The soil was modelled as series of springs. The springs stiffness’s (E.d) were

calculated using the following formulas:

• v is the vertical stress;

• .m is the mean stress;

• u is the hydrostatic pressure;

• G is the shear modulus of the soil;

• is Poisson’s ratio

• RF,G depends on the average rotational strain

d’/H

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• Step 4: Apply contraction giving a movement of d.d/2 at the end of the deck;

• Step 5: Apply expansion giving a movement of d.d at the end of the deck and

determine earth pressures applied to the abutment for this expansion case;

• Step 6: Compare the values of H’ and d’ for the back of the abutment with those

used in Step 3. If these are significantly different, repeat Steps 4 to 6 using

updated values of H’ and d’d;

• Step 7: Apply contraction giving a movement of d to the end of the deck and

determine earth pressures applied to the abutment for this contraction case;

• Step 8: Identify the depth below excavation level at which the earth pressure in

front of the abutment reduces to at rest pressure (H’) and the resulting

deflection d’ at H’/2; and

• Step 9: Compare the values of H’ and d’d for the front of the abutment with those

used in Step 3. If these are significantly different, repeat Steps 7 to 9 using

updated values of H’ and d.

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Construction Isues – Lessons Learnt

• Constructability of reinforcement in abutment walls;

• Anchor bolt installation required A lot of survey was required to ensure the

correct location;

• Beam precamber and deflections – pour sequencing

• Deck Construction Joint;

• Backfill of abutments;

• Piling – preference of industry for CFA, resistance by PTA.

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Construction Photos

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