ashton avenue integral bridge with battledeck slaboption3: using macalloy anchor bolts. battledeck...
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Ashton Avenue Integral Bridge with
Battledeck Slab
Behzad Golfa| Senior Structural Engineer
Presentation title
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
Presentation title
Longitudinal Elevation
of Old Bridge
Elevation of Old Bridge
4800
Presentation title
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.
Presentation title
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.
Presentation title
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
Presentation title
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.
Presentation title
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.
Presentation title
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.
Presentation title
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.
Presentation title
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.
Presentation title
Battledeck Bending Capacity
The design moment determined by plastic theory:
Presentation title
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
Presentation title
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
Presentation title
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
Presentation title
Design of Integral Bridges
Lateral Earth pressure k* (European Method)
Presentation title
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.
Presentation title
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.
Presentation title
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)
Presentation title
Horizontal earth pressures on abutments founded on piles
(without isolation device)
Earth pressures applied to the front of abutment (contraction case)
Presentation title
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
Presentation title
• 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.
Presentation title
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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www.ghd.com
THANK YOU FOR YOUR ATTENTION
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