Flexible Pavement Design Methods Heuristic Methods (early 1900s) - - PowerPoint PPT Presentation

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Flexible Pavement Design Methods Heuristic Methods (early 1900s) - - PowerPoint PPT Presentation

Jun 14, 2023 542 likes •828 views

Flexible Pavement Design Methods Heuristic Methods (early 1900s) Empirical Based on Soil Class (1920s) Empirical Based on Soil Strength (1930s) Limiting Shear Stress (1940s) Limiting Deflection (1950s) Regression-Based

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Flexible Pavement Design Methods

  • Heuristic Methods (early 1900s)
  • Empirical Based on Soil Class (1920s)
  • Empirical Based on Soil Strength (1930s)
  • Limiting Shear Stress (1940s)
  • Limiting Deflection (1950s)
  • Regression-Based (1960s)
  • Mechanistic-Empirical (21st Century)
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7133 Earth Structures

  • Analysis, design, and construction of earth

dams, levees, embankments and slopes; soil stabilization; seepage, drainage, and flow nets.

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Rigid Pavement Design Methods

  • 1919 – Goldbeck’s Formula
  • 1926 – Westergaard’s Equations
  • 1951 – Pickett’s Equations
  • 1965 – Finite Element Methods
  • 1979 – ILLI-SLAB
  • 1981 – WESLIQUID & WESLAYER
  • 1985 – KENSLABS
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Road Tests

  • Bates Road Test (rigid & flexible)
  • Maryland Road Test (rigid)
  • WASHO Road Test (flexible)
  • AASHO Road Test (flexible & rigid)
  • WesTrack (flexible)
  • NCAT Test Track (flexible)
  • SHRP LTPP (flexible & rigid)
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AASHO Road Test

Source: Highway Research Board Special Report 61A-G

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AASHO Road Test

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AASHO Road Test

Source: Highway Research Board Special Report 61A-G

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AASHO Road Test

Source: Highway Research Board Special Report 61A-G

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AASHO Road Test

Source: Highway Research Board Special Report 61A-G

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AASHO Road Test

Source: Highway Research Board Special Report 61A-G

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AASHO Road Test

Source: Highway Research Board Special Report 61A-G

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AASHO Road Test

Source: Highway Research Board Special Report 61A-G

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WesTrack

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WesTrack

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WesTrack

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NCAT Test Track

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NCAT Test Track

Source: Better Roads, November 2006

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NCAT Test Track

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SHRP LTPP

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Pavement Design Factors

  • Traffic

– Axle Loads – Contact Pressure – Load Repetitions – Vehicle Speed

  • Environment

– Temperature – Moisture – Freeze/Thaw

  • Materials

– Elastic Modulus – Poisson’s Ratio – Resilient Modulus – Creep Compliance – Fatigue Life – Subgrade Reaction – Modulus of Rupture – Strength

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Failure Criteria

  • Flexible Pavements

– Fatigue Cracking in Asphalt – Rutting in Asphalt and Base – Permanent Strain in Subgrade – Thermal Cracking in Asphalt

  • Rigid Pavements

– Fatigue Cracking in Slab – Permanent Strain in Subgrade

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Highway vs. Airport

  • Load Magnitudes
  • Load Durations
  • Contact Pressures
  • Traffic Volume
  • Tracking / Wander
  • Gear Configurations
  • Edge Effects
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Highway Wander

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Airport Wander

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Gear Configurations

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Dual Wheel – Single Axle