DESIGN & CONSTRUCTION OF BRIDGE No. 4163 OVER CRAVENS ...€¦ · Melbourne 23-24 Nov. 2015 Earth Structures & PRECAST ARCHES DESIGN Retention Conference The finite element analysis

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)


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


Earth Structures &

Retention ConferenceINTRODUCTION

Cravens Creek Bridge No. 4163 is situation at the East-West Arterial

Rd. ACT.


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This is a double arch bridge designed to replicate a traditional

masonry arch bridge with the use of precast elements and MSE

walls.


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Spandrel

SpandrelWingwall

AbutmentArchesAbutment

Wingwall

Wingwall

Wingwall

The arch structures are installed parallel.

Arches are 36m in length and span 18m each.


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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.


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Charcoal finish

Somme

Tobacco

finish


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TRADITIONAL MASONRY

ARCH BRIDGES

Typically constructed with natural stone, brick or blocks

Arched, with large supports


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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.


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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.


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THE PRECAST APPROACH TO

TRADITIONAL MASONRY ARCH BRIDGES

1. Precast Arches

2. Mechanically Stabilized Earth Walls


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.


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.


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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


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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.


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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.


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Concrete design complies with AS3600.


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Crown beam is designed to resist the shear load that develops when

the arches are loaded longitudinally


Earth Structures &

Retention ConferencePRECAST ARCHES CONSTRUCTION

1. Prepare the Site

2. Cast Footing with keyway

3. Mark out keyway for panel positions


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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.


Earth Structures &

Retention ConferenceARCH CONSTRUCTION SEQUENCE


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8. Grout Keyway.

9. Waterproof arch unit joints.

10. Backfill around the arch.


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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.


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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


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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


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.


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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.


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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


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.


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.


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


Earth Structures &

Retention ConferenceBRIDGE No.4163 BUILDING SEQUENCE


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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


Earth Structures &

Retention ConferenceCONCLUSIONS


Earth Structures &


Thank you for

your attention

[email protected]

Documents

DESIGN & CONSTRUCTION OF BRIDGE No. 4163 OVER CRAVENS ...€¦ · Melbourne 23-24 Nov. 2015 Earth Structures & PRECAST ARCHES DESIGN Retention Conference The finite element analysis