Evaluation of Non-Linear and Tension Cutoff Material Modeling Features for Pavement Base Aggregate
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Transcript of Evaluation of Non-Linear and Tension Cutoff Material Modeling Features for Pavement Base Aggregate
Western Transportation InstituteMontana State University-Bozeman
Evaluation of Non-Linear Evaluation of Non-Linear and Tension Cutoff and Tension Cutoff Material Modeling Material Modeling
Features for Pavement Features for Pavement Base AggregateBase Aggregate
Jeffrey SharkeyJeffrey SharkeyUndergraduate Research AssistantUndergraduate Research Assistant
Dr. Steven PerkinsDr. Steven PerkinsAssistant ProfessorAssistant Professor
Western Transportation InstituteMontana State University-Bozeman
OutlineOutline
Background InformationBackground Information Project Design/MethodologyProject Design/Methodology Results and FindingsResults and Findings ConclusionsConclusions
Western Transportation InstituteMontana State University-Bozeman
BackgroundBackground
Pavement design analysisPavement design analysis– Historical methods using empirical methodsHistorical methods using empirical methods– Recent methods using Finite Element Recent methods using Finite Element
AnalysisAnalysis Finite Element AnalysisFinite Element Analysis
– Wide range of applicationsWide range of applications– NCHRPNCHRP11 Design Guide Design Guide
1 1 National Cooperative Highway Research ProgramNational Cooperative Highway Research Program
Western Transportation InstituteMontana State University-Bozeman
BackgroundBackground
Western Transportation InstituteMontana State University-Bozeman
BackgroundBackground
Goal: Simplify FE methodGoal: Simplify FE method– Increase throughput of a systemIncrease throughput of a system– Increased productivityIncreased productivity– More accessibleMore accessible
Western Transportation InstituteMontana State University-Bozeman
MethodologyMethodology
Two ways of simplifying FE models:Two ways of simplifying FE models:– Reducing mesh resolutionReducing mesh resolution– Removing model featuresRemoving model features
Time:
Accuracy:
Percentage (%)
Western Transportation InstituteMontana State University-Bozeman
MethodologyMethodology
Two featuresTwo features– Tension cutoff formulationTension cutoff formulation– Non-linear behaviorNon-linear behavior
Issues choosing modulusIssues choosing modulus
Six source modelsSix source models– High, medium, and low traffic loads for High, medium, and low traffic loads for
Firm and Weak pavement surface Firm and Weak pavement surface designs.designs.
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MethodologyMethodology
Four sub-models:Four sub-models:A.A. Using both Using both
featuresfeatures
B.B. Removing Non-Removing Non-linear Behaviorlinear Behavior
C.C. Removing Tension-Removing Tension-cutoff Formulationcutoff Formulation
D.D. Removing both Removing both featuresfeatures
Non-Non-linear linear BehaviorBehavior
Linear Linear BehaviorBehavior
Tension-Tension-cutoffcutoff AA BBNo No Tension-Tension-cutoffcutoff CC DD
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FindingsFindings
Examining completed modelsExamining completed models– Physical output variablesPhysical output variables– Pavement fatigue lifePavement fatigue life– Cycles to permanent deformationCycles to permanent deformation
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Findings: UFindings: U22 and E and E2222
UU22 is deformation in vertical direction is deformation in vertical direction– Actual movementActual movement
EE2222 is strain in vertical direction is strain in vertical direction– Ratio of deformation to size of Ratio of deformation to size of
original un-deformed object.original un-deformed object.
EE22 22 = = ΔΔLL//LL00
Western Transportation InstituteMontana State University-Bozeman
High Firm EHigh Firm E2222
– LE: 19.3%LE: 19.3%– LETC: 19.3%LETC: 19.3%
High Firm UHigh Firm U22
– LE: 22.3%LE: 22.3%– LETC: 22.4%LETC: 22.4%
Western Transportation InstituteMontana State University-Bozeman
High Weak EHigh Weak E2222
– LE: 4.8%LE: 4.8%– LETC: 4.8%LETC: 4.8%
High Weak UHigh Weak U22
– LE: 17.7%LE: 17.7%– LETC: 17.7%LETC: 17.7%
Western Transportation InstituteMontana State University-Bozeman
Medium Firm EMedium Firm E2222
– LE: 18.7%LE: 18.7%– LETC: 19.0%LETC: 19.0%
Medium Firm UMedium Firm U22
– LE: 21.2%LE: 21.2%– LETC: 21.2%LETC: 21.2%
Western Transportation InstituteMontana State University-Bozeman
Medium Weak EMedium Weak E2222
– LE: 19.7%LE: 19.7%– LETC: 19.6%LETC: 19.6%
Medium Weak UMedium Weak U22
– LE: 30.1%LE: 30.1%– LETC: 30.0%LETC: 30.0%
Western Transportation InstituteMontana State University-Bozeman
Low Firm ELow Firm E2222
– LE: 17.0%LE: 17.0%– LETC: 16.9%LETC: 16.9%
Low Firm ULow Firm U22
– LE: 14.8%LE: 14.8%– LETC: 14.8%LETC: 14.8%
Western Transportation InstituteMontana State University-Bozeman
Low Weak ELow Weak E2222
– LE: 16.7%LE: 16.7%– LETC: 15.5%LETC: 15.5%
Low Weak ULow Weak U22
– LE: 33.1%LE: 33.1%– LETC: 41.0%LETC: 41.0%
Western Transportation InstituteMontana State University-Bozeman
Findings: UFindings: U22 and E and E2222
Physical output variablesPhysical output variables– Errors introduced into LE sub-models Errors introduced into LE sub-models
due to modulus calculation method.due to modulus calculation method.– Little difference noted when including or Little difference noted when including or
excluding tension cutoff formulation.excluding tension cutoff formulation. 0.28% (E0.28% (E2222), 1.68% (U), 1.68% (U22))
– Uniform results across source models.Uniform results across source models.
Western Transportation InstituteMontana State University-Bozeman
FindingsFindings
Pavement fatigue lifePavement fatigue life– High error compared to NLETC (24.2%)High error compared to NLETC (24.2%)– Average TC effectAverage TC effect
0.0% (high), 3.235% (med), 5.736% (low)0.0% (high), 3.235% (med), 5.736% (low)
Sub-model
High Firm
High Weak
Med Firm
Med Weak
Low Firm
Low Weak
LE 19.204 7.228 4.671 44.917 22.658 49.049
LETC 19.204 7.228 11.141 44.917 28.877 31.359
Western Transportation InstituteMontana State University-Bozeman
FindingsFindings
Cycles to permanent deformationCycles to permanent deformation– Again, high error compared to NLETC (22.0%)Again, high error compared to NLETC (22.0%)– Average TC effectAverage TC effect
0.0% (high), 0.616% (med), 5.034% (low)0.0% (high), 0.616% (med), 5.034% (low)
Sub-model
High Firm
High Weak
Med Firm
Med Weak
Low Firm
Low Weak
LE 12.332 7.208 4.146 49.838 14.783 16.480
LETC 12.332 7.208 5.378 49.838 11.339 29.991
Western Transportation InstituteMontana State University-Bozeman
ConclusionsConclusions
Non-linear behaviorNon-linear behavior– Can be removed Can be removed onlyonly when modulus is when modulus is
carefully chosen.carefully chosen. Tension cutoff formulationTension cutoff formulation
– Little difference notedLittle difference noted– More important for cycles calculations More important for cycles calculations
as traffic loads decrease.as traffic loads decrease. RecommendationsRecommendations
Western Transportation InstituteMontana State University-Bozeman
ConclusionsConclusions
Goal: Simplify FE methodGoal: Simplify FE method– Increase throughput of a systemIncrease throughput of a system– Increased productivityIncreased productivity– More accessibleMore accessible
Thank youThank you– Dr. Steven PerkinsDr. Steven Perkins– Western Transportation InstituteWestern Transportation Institute