Difference in Estimated Layer Moduli from Static and Dynamic Back-calculations

A falling weight deflectometer (FWD) is commonly utilized to make structural evaluation of pavement systems, which applies impulsive force at a surface of pavement and measure surface deflections. Static back-calculation employs only peak force and peak deflections, while dynamic back calculation uses time histories of both. Since dynamic analysis of elastic multi-layered systems required in its back-calculation routine of the latter method is extremely time consuming, reducing computational time required for the dynamic analysis is very important. Dynamic reduction analysis method based on Ritz vectors is implemented in the algorithm. In both back-calculation routines, truncated singular value decomposition technique is introduced to improve numerical stability. The results from both methods are presented and discussed.