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Melbourne 23-24 Nov. 2015
Earth Structures &
Retention Conference
Antonio Ramirez Martinez(Design Engineer)
Reinforced Earth
Caroline Stack(Design Engineer)
Reinforced Earth
A NEW APPROACH TO
TRADITIONAL MASONRY
ARCH BRIDGES
DESIGN & CONSTRUCTION OF BRIDGE
No. 4163 OVER CRAVENS CREEK AT
EAST-WEST ARTERIAL STAGE 2 (ACT)
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceOUTLINE
1. INTRODUCTION
2. TRADITIONAL MASONRY ARCH BRIDGES
3. THE PRECAST APPROACH TO TRADITIONAL
MASONRY ARCH BRIDGES
4. BRIDGE No.4163 BUILDING SEQUENCE
5. CONCLUSIONS
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceINTRODUCTION
Cravens Creek Bridge No. 4163 is situation at the East-West Arterial
Rd. ACT.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceINTRODUCTION
This is a double arch bridge designed to replicate a traditional
masonry arch bridge with the use of precast elements and MSE
walls.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceINTRODUCTION
Spandrel
SpandrelWingwall
AbutmentArchesAbutment
Wingwall
Wingwall
Wingwall
The arch structures are installed parallel.
Arches are 36m in length and span 18m each.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceINTRODUCTION
Balustrade Balustrade
Charcoal finishCharcoal finish
Somme
Tobacco
finish
The precast facing panels have varied finishes to replicate the stone
spandrel, wingwalls and balustrades of a traditional masonry bridge.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceINTRODUCTION
Charcoal finish
Somme
Tobacco
finish
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention Conference
TRADITIONAL MASONRY
ARCH BRIDGES
Typically constructed with natural stone, brick or blocks
Arched, with large supports
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention Conference
TRADITIONAL MASONRY
ARCH BRIDGES
Compression forces are transferred outward along the arch curve
towards the abutments.
Tensile forces are almost negligible.
Substantial material required at sides to avoid arch spreading or
central section collapsing inwards.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention Conference
TRADITIONAL MASONRY
ARCH BRIDGES
Main advantages are their
durability and architectural
attractiveness.
Disadvantages include Complex
and labour-intensive construction.
They can vary aesthetically with
similar basic structure.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention Conference
THE PRECAST APPROACH TO
TRADITIONAL MASONRY ARCH BRIDGES
1. Precast Arches
2. Mechanically Stabilized Earth Walls
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferencePRECAST ARCHES
Two opposite precast arch units are assembled to form a three-hinged
arch structure.
This technology is a rapid and simple method of construction.
Arches can be complimented with MSE head walls, allowing for unique
architectural features.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferencePRECAST ARCHES DESIGN
First, we develop the funicular arch shape considering the clearance
box required inside the arch and geometry of the surrounding soil.
For developing geometrical characteristics of the arch, it is assumed no
bending moment occurs in the arch.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferencePRECAST ARCHES DESIGN
Forces in the elements must be calculated for various stages of
construction including:
- Lifting of the arch units for handling and construction
- Resting on their ends just before being lifted into position
- Assembled units prior to backfilling considering effects of
wind loads
- All stages of Backfilling
- Live loads at road level
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferencePRECAST ARCHES DESIGN
Reinforced Earth Group developed a specific finite element program
called AZTECH to model the soil and arches together.
AZTECH is a non- linear elasto-plastic finite element program, which
allows us to analyse the backfilling lifts around the arch.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferencePRECAST ARCHES DESIGN
The finite element analysis is carried out for a number of load cases.
The backfill around the arch is the most complicated material to
model but has the greatest effect on the arch.
The final load cases analysed by the finite element model are the live
loads on the surface, where the most critical cases are of the
asymmetric live loads.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferencePRECAST ARCHES DESIGN
Concrete design complies with AS3600.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferencePRECAST ARCHES DESIGN
Crown beam is designed to resist the shear load that develops when
the arches are loaded longitudinally
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferencePRECAST ARCHES CONSTRUCTION
1. Prepare the Site
2. Cast Footing with keyway
3. Mark out keyway for panel positions
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferencePRECAST ARCHES CONSTRUCTION
4. Lift, position and hold first arch unit in place with crane.
5. Lift, position and hold opposite arch unit in place with crane.
6. Release panels
7. Repeat installing method for remaining arch units.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceARCH CONSTRUCTION SEQUENCE
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferencePRECAST ARCHES CONSTRUCTION
8. Grout Keyway.
9. Waterproof arch unit joints.
10. Backfill around the arch.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferencePRECAST ARCHES CONSTRUCTION
There are 3 zones of backfilling required around the arch.
Once the backfill reaches the crown of the arches, the in-situ crown
beam is then cast.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention Conference
PRECAST ARCHES CONSTRUCTION
In situ Footing
Arch Units
Erection
Backfilling
Crown
Beam
0.5m Max.
0.5m Max.
0.5m Max.
Waterproofing
ARCH CONSTRUCTION SEQUENCE
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention Conference
MECHANICALLY
STABILISED EARTH (MSE)
Composite material formed by the interaction of a cohesionless
granular soil and reinforcing strips
Reinforcing strips resist stresses produced within the soil mass
Precast Concrete panels are used at the facing for the reinforced block
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceMSE DESIGN
Valdez is a limit state program, used to check the internal and
external stability.
Basic equilibrium equations are
used to check the overturning,
sliding and bearing pressure of the
MSE block.
Analysis of the active pressure at
the rear of the reinforced earth block,
self-weight of the block, Meyerhof
pressure and any applied loads.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceMSE DESIGN
Internal stability analysis checks the maximum applied forces at each
layer of reinforcing strips.
Frictional resistance and tensile strength of each strip is calculated.
The number of strips required is developed by comparing these results
to strip capacity.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceMSE DESIGN
STARES is a limit equilibrium stability analysis program using an analysis
based on Bishop's simplified method for unreinforced slopes.
Resultant forces are developed in vertical slices within the generated
circle of slip failure
Reinforcing strips restrain the forces through slices
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceMSE CONSTRUCTION
1. Prepare the Site.
2. Cast Levelling pads.
3. Place initial course of panels with crane.
4. Prop and clamp panels before releasing from crane.
5. Cover joints with specified geotextile.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceMSE CONSTRUCTION
6. Place and compact backfill behind the panel up to the first row of
tie points.
7. Place reinforcing strips on the compacted backfill.
8. Connect reinforcing strip to the cast-in tie strip at rear of panel.
9. Repeat the cycle, placing bearing pads at horizontal joints, until the
design height is reached.
10. Install capping units.
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceBRIDGE No.4163.
BUILDING SEQUENCE
INSERT MODEL
In situ Footing & Arch UnitsConstruction of
MSE Abutment & Spandrel
Completion
of Embedment
Installation of Capping
&
Pavement
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceBRIDGE No.4163 BUILDING SEQUENCE
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceBRIDGE No.4163 BUILDING SEQUENCE
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceBRIDGE No.4163 BUILDING SEQUENCE
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceBRIDGE No.4163 BUILDING SEQUENCE
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceCONCLUSIONS
Bridge No. 4163 achieves a traditional masonry arch bridge key features,
durability and architectural attractiveness, with the use of precast
arches together with MSE walls, while also adding the following
benefits:
- Faster and easier construction
- More economical
- Flexible design methods
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention ConferenceCONCLUSIONS
Melbourne 23-24 Nov. 2015
Earth Structures &
Retention Conference
Thank you for
your attention
cstack@reco.com.au
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