Numerical Simulations of FWD and TSD Loading and the Effects on Pavement Surface Deflection

Pavement surface deflection is essential to assess the structural performance of pavements and to accordingly design the most suitable rehabilitation strategies. Various deflectometer devices can measure these deflections in different manners. A falling weight deflectometer (FWD) measures surface deflection responses to an impulsive and stationary load. A traffic speed deflectometer (TSD), in contrast, simultaneously records deflection data under vehicle-moving speed. Many studies have reported the different responses of FWD and TSD under simple assumptions. Additionally, even though both devices utilize an unidentical loading pattern, the deflection data are still interpreted by the same radial location, indices, and curvature. This study aimed at comparing the outcomes of FWD and TSD loading by fully looking at the surface deflections and other responses under various scenarios. This comparison was numerically conducted by a three-dimensional (3D) finite element method and 3D-Move software. Dynamic effect and time- and temperature-dependent material behavior were considered in the analysis. The effects of pavement thickness, material, roughness, and speed were also discussed.