ECGD4228 Transportation Engineering II Summer 2008 Saturdays 15:30-18:30 PM K204 - PowerPoint PPT Presentation

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ECGD4228 Transportation Engineering II Summer 2008 Saturdays 15:30-18:30 PM K204 PowerPoint Presentation
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ECGD4228 Transportation Engineering II Summer 2008 Saturdays 15:30-18:30 PM K204

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ECGD4228 Transportation Engineering II Summer 2008 Saturdays 15:30-18:30 PM K204
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ECGD4228 Transportation Engineering II Summer 2008 Saturdays 15:30-18:30 PM K204

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  1. ECGD4228 Transportation Engineering II Summer 2008 Saturdays 15:30-18:30 PM K204 Dr. Wa'el M. Albawwab albawwab@gmail.com

  2. Lecture 6 • Pavement Design Methods • Design Parameters • Flexible Pavement • Rigid Pavement Dr. Wa'el M. Albawwab albawwab@gmail.com

  3. Distribution of Stresses & Temperatures Dr. Wa'el M. Albawwab albawwab@gmail.com

  4. Present Serviceability Rating (PSR) Picture from: Highway Research Board Special Report 61A-G Dr. Wa'el M. Albawwab albawwab@gmail.com

  5. Present Serviceability Index (PSI) • Values from 0 through 5 • Calculated value to match PSR SV = mean of the slope variance in the two wheelpaths (measured with the CHLOE profilometer or BPR Roughometer) C, P = measures of cracking and patching in the pavement surface Dr. Wa'el M. Albawwab albawwab@gmail.com

  6. Present Serviceability Index (PSI) • C = total linear feet of Class 3 and Class 4 cracks per 1000 ft2 of pavement area: • A Class 3 crack is defined as opened or spalled (at the surface) to a width of 0.25 in. or more over a distance equal to at least one-half the crack length. • A Class 4 is defined as any crack which has been sealed. • P = expressed in terms of ft2 per 1000 ft2 of pavement surfacing. Dr. Wa'el M. Albawwab albawwab@gmail.com

  7. Typical LEF’s Notice that cars are insignificant and thus usually ignored in pavement design. Dr. Wa'el M. Albawwab albawwab@gmail.com

  8. Design Catalog Example design catalog from the Washington Asphalt Pavement Association (WAPA) for residential streets Dr. Wa'el M. Albawwab albawwab@gmail.com

  9. AASHTO Flexible PavementDesign Formula Dr. Wa'el M. Albawwab albawwab@gmail.com

  10. AASHTO Rigid PavementDesign Formula Dr. Wa'el M. Albawwab albawwab@gmail.com

  11. Terminologies • W18 (loading) • Predicted number of ESALs over the pavement’s life. • D (slab depth) • Abstract number expressing structural strength • SN = a1D1 + a2D2m2 + a3D3m3 + … • S’c (PCC modulus of rupture) • A measure of PCC flexural strength • Usually between 600 and 850 psi • Cd (drainage coefficient) • Relative loss of strength due to drainage characteristics and the total time it is exposed to near-saturated conditions • Usually taken as 1.0 Dr. Wa'el M. Albawwab albawwab@gmail.com

  12. Terminologies • J (load transfer coefficient) • Accounts for load transfer efficiency • Lower J-factors = better load transfer • Between 3.8 (undoweled JPCP) and 2.3 (CRCP with tied shoulders) • Ec (PCC elastic modulus) • 4,000,000 psi is a good estimate • k (modulus of subgrade reaction) • Estimates the support of the PCC slab by the underlying layers • Usually between 50 and 1000 psi/inch Dr. Wa'el M. Albawwab albawwab@gmail.com

  13. Reliability Reliability = P [Y > X] X = Probability distribution of stress(e.g., from loading, environment, etc.) Y = Probability distribution of strength(variations in construction, material, etc.) Probability Stress/Strength Dr. Wa'el M. Albawwab albawwab@gmail.com

  14. Basic AASHTO Flexible PavementDesign Method Determine the desired terminal serviceability, pt Convert traffic volumes to number of equivalent 18-kip single axle loads (ESAL) Determine the structural number, SN Determine the layer coefficients, ai Solve layer thickness equations for individual layer thickness Dr. Wa'el M. Albawwab albawwab@gmail.com

  15. Basic AASHTO Rigid PavementDesign Method Select terminal serviceability Determine number of ESALs Determine the modulus of sub-grade reaction Determine the slab thickness Dr. Wa'el M. Albawwab albawwab@gmail.com

  16. Dr. Wa'el M. Albawwab albawwab@gmail.com

  17. Dr. Wa'el M. Albawwab albawwab@gmail.com

  18. Dr. Wa'el M. Albawwab albawwab@gmail.com

  19. Dr. Wa'el M. Albawwab albawwab@gmail.com

  20. Dr. Wa'el M. Albawwab albawwab@gmail.com

  21. Dr. Wa'el M. Albawwab albawwab@gmail.com

  22. Dr. Wa'el M. Albawwab albawwab@gmail.com

  23. Dr. Wa'el M. Albawwab albawwab@gmail.com

  24. Dr. Wa'el M. Albawwab albawwab@gmail.com

  25. Dr. Wa'el M. Albawwab albawwab@gmail.com

  26. Dr. Wa'el M. Albawwab albawwab@gmail.com

  27. Dr. Wa'el M. Albawwab albawwab@gmail.com

  28. Economic Analysis Different treatments results in different designs Evaluate cost of different alternatives Dr. Wa'el M. Albawwab albawwab@gmail.com

  29. Sensitivity Analysis Input different values of traffic volume Compare resulting differences in pavement Fairly significant differences in ADT do not yield equally significant differences in pavement thickness Dr. Wa'el M. Albawwab albawwab@gmail.com

  30. Dr. Wa'el M. Albawwab albawwab@gmail.com

  31. Dr. Wa'el M. Albawwab albawwab@gmail.com