Integral Bridges

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Integral Bridges

• Development of a constitutive model for soil
  structure interaction

2008 Structures Congress - Crossing Borders
April 24-26, 2008
James Banks Alan Bloodworth Thomas Knight Jeffery
Young
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Integral Bridges

• Concept
• Problem
• Fundamental Behaviour
• Soil Modelling
• Implementation, Testing and Validation
• Further Work
• Outcomes

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Integral Bridges
g

• Short Span Bridges
• Full/Shallow height
• Backfilled/embedded
• No expansion joints or bearings
• Reduced maintenance and construction costs

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The Problem
g
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Soil Element Behaviour
g

• Granular material
• Typical loading for Integral bridge
• Radial Strain - controlled Cyclic Triaxial Tests
• fundamental behaviour for a single element of
  soil behind an abutment

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Soil Element Behaviour
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Mathematical Model

• Mathematical Description of the Soil
• Parameters
• Youngs Modulus (Eh)
• Axial Strain (?ea)
• Relative Density (DR)
• Pre-dilation
• Eh and ?ea are proportional to DR
• Post-dilation
• Same behaviour continues

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Hardening Parameter
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Element Modelling in Excel
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FLAC Model of Element
g

• Modelled in FDM programme FLAC
• Single axi-symmetric element for triaxial tests
• Failure represented by Mohr-Coulomb

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FLAC Model of Element
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Further Work
g
Centrifuge Prototype Modelled in FLAC
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Further Work
g

• Magnitudes
• Triangular Stress Envelope

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Outcomes
g

• Modelled fundamental behaviour
• Implemented and Validated model
• Extended Model to abutment system
• Better bridges

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www.mottmac.com
www.civil.soton.ac.uk
James Banks - james.banks_at_mottmac.com