Influence of the Accuracy of a Bridge Weigh-In-Motion System on the Determination of a Bridge Assess...
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Influence of the Accuracy of a Bridge Weigh-In-Motion System on the Determination of a Bridge Assessment Dynamic Ratio. Jason Dowling Arturo González Eugene O’Brien. Quick Overview. - Bridge Weigh-In-Motion Model Description Assessment Dynamic Ratio Bridge Weigh-In-Motion Accuracy.

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Jason dowling arturo gonz lez eugene o brien

Influence of the Accuracy of a Bridge Weigh-In-Motion System on the Determination of a Bridge Assessment Dynamic Ratio

Jason Dowling

Arturo González

Eugene O’Brien


Jason dowling arturo gonz lez eugene o brien

Quick Overview on the Determination of a Bridge Assessment Dynamic Ratio

  • - Bridge Weigh-In-Motion

  • Model Description

  • Assessment Dynamic Ratio

  • Bridge Weigh-In-Motion Accuracy


Jason dowling arturo gonz lez eugene o brien

Bridge Weigh-In-Motion on the Determination of a Bridge Assessment Dynamic Ratio

Bridge Weigh-In-Motion systems use instrumented bridges to collect data on the truck fleet at a specific location.

  • - This concept was first proposed by Moses (1979)

  • Strain transducers are attached to the soffit of a bridge

  • Axle detectors are placed on the road surface

  • An algorithm is used to interpret the data

source: WAVE (2001)


Jason dowling arturo gonz lez eugene o brien

Bridge Weigh-In-Motion on the Determination of a Bridge Assessment Dynamic Ratio

  • Moses Algorithm (1979) remains the most popular algorithm used in Bridge Weigh-In-Motion systems.

  • - Based on minimizing the sum of squares of differences between theory and measurements:

Lots of measurements are available during the truck crossing...

- This is utilised to smooth out the dynamic component.


Jason dowling arturo gonz lez eugene o brien

Bridge Weigh-In-Motion on the Determination of a Bridge Assessment Dynamic Ratio

Typical ‘Measured’ Response


Jason dowling arturo gonz lez eugene o brien

Bridge Weigh-In-Motion on the Determination of a Bridge Assessment Dynamic Ratio

Theoretical Response

x


Jason dowling arturo gonz lez eugene o brien

Bridge Weigh-In-Motion on the Determination of a Bridge Assessment Dynamic Ratio

Matrix Solution Technique

Minimizing the Error function,

gives a system of simultaneous equations in Wi

Where {W} is a vector of the desired axle weights


Jason dowling arturo gonz lez eugene o brien

Model Description on the Determination of a Bridge Assessment Dynamic Ratio

Truck Model

- 8 Degrees of Freedom


Jason dowling arturo gonz lez eugene o brien

Model Description on the Determination of a Bridge Assessment Dynamic Ratio

Data Used for simulations of truck crossings...

Statistical Data for - GVW & Velocity

- Axle Spacing

- Axle Weights


Jason dowling arturo gonz lez eugene o brien

Model Description on the Determination of a Bridge Assessment Dynamic Ratio

Data Used for simulations of truck crossings...

Carpet Profile


Jason dowling arturo gonz lez eugene o brien

Model Description on the Determination of a Bridge Assessment Dynamic Ratio

Model Accuracy Classification

COST323 (2002) proposed a method of classification for Bridge Weigh-In-Motion systems

- The models classification under this method is ‘B+(7)’

  • Most individual axle weights predicted within ± 7%

  • Axle group weights & GVW predicted within ± 5%


Jason dowling arturo gonz lez eugene o brien

Assessment Dynamic Ratio on the Determination of a Bridge Assessment Dynamic Ratio

Assessment Dynamic Ratio (ADR) is defined as:

i.e. Not necessarily associated with a single loading event

Recent work has discovered a tendency for ADR to decrease as Return Period, or Load Effect increases.


Jason dowling arturo gonz lez eugene o brien

Assessment Dynamic Ratio on the Determination of a Bridge Assessment Dynamic Ratio

Trends in ADR with Time...

source: Rattigan (2007)


Jason dowling arturo gonz lez eugene o brien

Assessment Dynamic Ratio on the Determination of a Bridge Assessment Dynamic Ratio

Trends in ADR with Time...

source: SAMARIS (2006)


Jason dowling arturo gonz lez eugene o brien

Assessment Dynamic Ratio on the Determination of a Bridge Assessment Dynamic Ratio

Trends in ADR with Time...


Jason dowling arturo gonz lez eugene o brien

Bridge Weigh-In-Motion Accuracy on the Determination of a Bridge Assessment Dynamic Ratio

Inferred Static Response


Jason dowling arturo gonz lez eugene o brien

Bridge Weigh-In-Motion Accuracy on the Determination of a Bridge Assessment Dynamic Ratio

Inferred Static Response


Jason dowling arturo gonz lez eugene o brien

Bridge Weigh-In-Motion Accuracy on the Determination of a Bridge Assessment Dynamic Ratio

Inferred Static Response

Error in Maximum Static


Jason dowling arturo gonz lez eugene o brien

Bridge Weigh-In-Motion Accuracy on the Determination of a Bridge Assessment Dynamic Ratio

Error in prediction of ADR


Jason dowling arturo gonz lez eugene o brien

In Summary: on the Determination of a Bridge Assessment Dynamic Ratio

Moses Algorithm tends to over estimate the maximum static response.

This leads to an underestimation of ADR

Future work will look at further understanding this inaccuracy

With a view to quantifying this or suggesting possible remediation measures...


Jason dowling arturo gonz lez eugene o brien

My Thanks to the 6th European Framework Project ARCHES (Assessment and Rehabilitation of Central European Highway Structures) for funding my work.

Thank you for listening.