evaluation of predicted pavement response using …€¦ · 3 background • state has seen large...

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DaeDae--Wook ParkWook ParkQuality Engineering Solutions, Inc.Quality Engineering Solutions, Inc.

Emmanuel FernandoEmmanuel FernandoTexas Transportation InstituteTexas Transportation Institute

Joe LeidyJoe LeidyTexas Department of TransportationTexas Department of Transportation

EVALUATION OF PREDICTED EVALUATION OF PREDICTED PAVEMENT RESPONSE USING PAVEMENT RESPONSE USING

MEASURED TIRE CONTACT MEASURED TIRE CONTACT STRESSESSTRESSES

BackgroundBackground

•• State has seen large increase in State has seen large increase in special carrier loadsspecial carrier loads

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•• High diversity of tire sizes and High diversity of tire sizes and pressurespressures




•• Change in transportation codeChange in transportation code

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•• Change in transportation codeChange in transportation code•• Future changes to general trucking Future changes to general trucking

industryindustry

Background (cont.)• Assumptions used in

existing pavement analysis programs:

wheel loads are defined as having circular footprintfootprint size defined by tire inflation pressurecontact pressure assumed uniform

• How does tire design affect:

contact pressuresprimary responses to loading within the pavement structure

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Research Objectives

• Determine how tire footprint and contact pressure distribution vary with tire type

• Evaluate how results can be used in existing layered elastic programs

How were objectives pursued?

• Collect tire contact pressure data• Analyze data• Predict pavement response• Develop computer program

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Available Tire Contact Pressure Measurements

• U.C. Berkeley data (1997):Conventional radial (11R22.5)Low profile (295/75R22.5)

• TTI data (2002):11R24.5 radial215/75R17.5 radial

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Evaluation of Tire Contact Patches

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Evaluation of Tire Contact Area

• Tire contact patches were scanned as necessary

• Tire contact area determined based on shading of pixels of scanned image

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ANALYSIS OF TIRE CONTACT STRESS DATA

ORIGINALORIGINAL DECIMATEDDECIMATED

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Total Loads: Original vs. Decimated

∑ ××=e

i LFSPLoadTotal 1

Evaluate Finite Element Mesh Configuration

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3D FINITE ELEMENT MESH

Top view Elevation view

LoadingArea

3.81 m

Asphalt = 152 mm

Base = 304 mm

Subgrade = Infinite

MODELING TIRE CONTACT PRESSURES

• Use 3D finite element analysis• Run ABAQUS and BISAR programs

BISAR with measured tire contact areaBISAR with conventional procedure

• Compare ABAQUS and BISAR results

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Pavement Response Predictions

Layered Elastic Analysis• Conventional – inflation pressure

assumed as tire contact pressure acting uniformly on a circular area

A Ppc

i

= rAc=π

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Layered Elastic Analysis• Modified – contact area determined

based on tire type, tire load and tire inflation pressure. Then, equivalent circular pressure distribution is determined.

p PAm

=rAm=π

FINDINGS FROM COMPARISON OF ABAQUS AND LAYERED ELASTIC PREDICTIONS

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Differences greatest near surface and diminish with depth

Effect of tire contact area on fatigue predictions

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Findings – Comparison of ABAQUS & Layered Elastic Predictions

• Differences in predicted fatigue life and Mohr-Coulomb value vary with tire type

• Differences are greatest near surface and diminish with depth

• Overall, predicted fatigue life and Mohr-Coulomb value from modified analysis closer to ABAQUS

• Recommend using modified analysis for approximation using prediction equations for tire contact area

Other Findings

215/75R17.5Most damaging

11R24.5

295/75R22.5

11R22.5Least damaging

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PREDICTION OF TIRE CONTACT PRESSURES

Measured vs predicted vertical tire contact forces for the 11R24.5 tire at 6200 lb tire load and 130 psi inflation pressure.

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Program for Predicting Tire Contact Pressures

Program for Predicting Tire Contact Forces

evaluation of predicted pavement response using …€¦ · 3 background • state has seen large...

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