Multiple wheel-load interaction in flexible pavements

Various highway vehicle axle-wheel arrangements and aircraft gearwheel configurations adopted currently to accommodate increasing load levels affect, according to different multiple wheel-loading scenarios, flexible pavement response and performance. The traditional approach of single wheel-load response superposition, especially in the case of nonlinear analysis, may not be adequate to analyze pavements subjected to such multiple wheel-load cases. These complex loading conditions require advanced pavement layered solutions for realistic consideration of non-linear behavior of pavement foundation geomaterials (e.g., fine-grained subgrade soils and unbound aggregates used in untreated base-subbase layers), and at the same time use three-dimensional (3-D) finite element (FE) analyses to apply multiple wheel loading. In this study, stressdependent resilient modulus models successfully incorporated into the 3-D FE-based mechanistic pavement analysis through a programmed user material subroutine in ABAQUS were used to predict pavement resilient responses at observed critical-load locations. The results indicated that proper characterizations of the nonlinear, stress-dependent pavement foundation geomaterials significantly affected predictions of critical pavement responses. Most important, pavement responses under multiple wheel loads were somewhat different from those obtained from the single wheel-load response superposition approach, which suggested the need for 3-D nonlinear FE analyses for improved response predictions.