Determining the Effects of Cross-Anisotropy on Pavement Response and Performance
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2017-12-31
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TRIS Online Accession Number:01682398
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Edition:Final Report
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Abstract:This study is performed to investigate the effect of cross-anisotropy in Asphalt Concrete (AC) on pavement responses, i.e., stress-strain, and performance, i.e., damage due to fatigue and permanent deformation. To date, a full-scale Finite Element Model (FEM) of an instrumented pavement section is developed in ABAQUS 6-EF-2. Laboratory tests were conducted on AC cores and aggregates to inputs for material models: (a) cross-anisotropic and viscoelasticity for AC layer, and (b) nonlinear elasticity and stress-dependency for aggregate layers. The developed material models are integrated to ABAQUS via User Defined Material (UMAT) interface. The full-scale FEM is validated by comparing the simulated pavement responses with those measured by field instrumentation under a Falling Weight Deflectometer (FWD) test load. Later, a parametric study is performed by simulating the FEM at varying parameters such as degree of cross-anisotropy (n-value) in AC layer, pavement temperature, and so on. It is observed that the tensile strain at the bottom of AC layer and resulting fatigue damage increases whenever AC is cross-anisotropic. This effect is enhanced in presence of high pavement temperature, unbound layer cross-anisotropy, and nonlinearity. Vertical compressive strain as well as damage due to permanent deformation are also sensitive to AC cross-anisotropy and follows the similar type of trend. Effect of AC cross-anisotropy on these strains and damage are very high in unbound layers, specially, base and subbase. In addition, presence of high temperature and base layer cross-anisotropy. It is observed that variation in loading duration highly affects vertical strain and permanent deformation in pavement layers.
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