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Evaluation of Non-Linear and Tension Cutoff Material Modeling Features for Pavement Base Aggregate

Evaluation of Non-Linear and Tension Cutoff Material Modeling Features for Pavement Base Aggregate. Jeffrey Sharkey Undergraduate Research Assistant Dr. Steven Perkins Assistant Professor. Outline. Background Information Project Design/Methodology Results and Findings Conclusions.

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Evaluation of Non-Linear and Tension Cutoff Material Modeling Features for Pavement Base Aggregate

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  1. Evaluation of Non-Linear and Tension Cutoff Material Modeling Features for Pavement Base Aggregate Jeffrey Sharkey Undergraduate Research Assistant Dr. Steven Perkins Assistant Professor

  2. Outline • Background Information • Project Design/Methodology • Results and Findings • Conclusions

  3. Background • Pavement design analysis • Historical methods using empirical methods • Recent methods using Finite Element Analysis • Finite Element Analysis • Wide range of applications • NCHRP1 Design Guide 1 National Cooperative Highway Research Program

  4. Background

  5. Background • Goal: Simplify FE method • Increase throughput of a system • Increased productivity • More accessible

  6. Methodology • Two ways of simplifying FE models: • Reducing mesh resolution • Removing model features Time: Accuracy: Percentage (%)

  7. Methodology • Two features • Tension cutoff formulation • Non-linear behavior • Issues choosing modulus • Six source models • High, medium, and low traffic loads for Firm and Weak pavement surface designs.

  8. Methodology • Four sub-models: • Using both features • Removing Non-linear Behavior • Removing Tension-cutoff Formulation • Removing both features

  9. Findings • Examining completed models • Physical output variables • Pavement fatigue life • Cycles to permanent deformation

  10. Findings: U2 and E22 • U2 is deformation in vertical direction • Actual movement • E22 is strain in vertical direction • Ratio of deformation to size of original un-deformed object. E22 = ΔL/L0

  11. High Firm E22 • LE: 19.3% • LETC: 19.3% • High Firm U2 • LE: 22.3% • LETC: 22.4%

  12. High Weak E22 • LE: 4.8% • LETC: 4.8% • High Weak U2 • LE: 17.7% • LETC: 17.7%

  13. Medium Firm E22 • LE: 18.7% • LETC: 19.0% • Medium Firm U2 • LE: 21.2% • LETC: 21.2%

  14. Medium Weak E22 • LE: 19.7% • LETC: 19.6% • Medium Weak U2 • LE: 30.1% • LETC: 30.0%

  15. Low Firm E22 • LE: 17.0% • LETC: 16.9% • Low Firm U2 • LE: 14.8% • LETC: 14.8%

  16. Low Weak E22 • LE: 16.7% • LETC: 15.5% • Low Weak U2 • LE: 33.1% • LETC: 41.0%

  17. Findings: U2 and E22 • Physical output variables • Errors introduced into LE sub-models due to modulus calculation method. • Little difference noted when including or excluding tension cutoff formulation. • 0.28% (E22), 1.68% (U2) • Uniform results across source models.

  18. Findings • Pavement fatigue life • High error compared to NLETC (24.2%) • Average TC effect • 0.0% (high), 3.235% (med), 5.736% (low)

  19. Findings • Cycles to permanent deformation • Again, high error compared to NLETC (22.0%) • Average TC effect • 0.0% (high), 0.616% (med), 5.034% (low)

  20. Conclusions • Non-linear behavior • Can be removed only when modulus is carefully chosen. • Tension cutoff formulation • Little difference noted • More important for cycles calculations as traffic loads decrease. • Recommendations

  21. Conclusions • Goal: Simplify FE method • Increase throughput of a system • Increased productivity • More accessible • Thank you • Dr. Steven Perkins • Western Transportation Institute

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