e. structural response 2012 - purdue university college of engineering · 2015. 10. 8. · e....
TRANSCRIPT
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CE 461 Roadway and Pavement Design
A model that defines the response of the pavement to loading in terms of stresses, strains, and deflections
P
L/2 L/2
δmax
EIPL48
3max =δ
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Differ in: Capabilities Complexity Material Input Requirements Underlying Assumptions
Provide σ, ε, δ anywhere and in any direction in the pavement structure
Handle dynamic loading HMA modeled as visco-‐elastic PCC modeled as linear-‐elastic Base and subgrade modeled as non-‐linear inelastic Consider temperature stresses
DOES NOT EXIST Would require tremendous material properties inputs
Significant progress has been made
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Multilayer elastic theory Finite element methods Visco-‐elastic theory Dynamic analysis Thermal models
Complexity of model Material property input requirements Computational time Relative accuracy
Flexible pavements Fatigue cracking Rutting Thermal cracking Others
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Alligator cracking in asphalt layer Horizontal tensile strain at the bottom of the asphalt layer
Base material will not take tension Limit tensile strain in asphalt layer
Base Course
HMA
Subgrade
Compression
Tension
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Base Course
HMA
Subgrade
σc
Base Course
HMA
Subgrade
Thermal Contraction
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Rigid pavements Fatigue cracking Pumping/erosion Others
Stress at mid-‐slab Temperature differential
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Ttop > Tbottom
Ttop < Tbottom Day
Night
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Loss of fines Corner breaks Faulting
Travel Direction
Rebo
und
Defl
ectio
n
Loss of fines Fines Deposited
Trailing Slab Leading Slab
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Many cannot be addressed in pavement design Materials problems
One must develop an understanding of the stresses involved in order to design the material and the thickness