This document presets a new approach to determining layered elastic moduli from in situ loaddeflection data, which was developed under the Federal Highway Administration’s project for reviewing Long-Term Pavement Performance (LTPP) backcalculation data. This approach is called forwardcalculation, and it differs from backcalculation in that modulus estimates are calculated directly from the load and deflection data using closed-form formulae rather than through iteration. The closedform forwardcalculation equations are used for the subgrade and the bound surface course, respectively, for both flexible and rigid pavement falling weight deflectometer (FWD) data. Intermediate layer moduli are estimated through commonly used modular ratios between adjacent layers. The audience for this document includes highway agency engineers, researchers, and consultants who are involved in pavement analysis, design, construction, and deflection data analysis. (Author/publisher)
Abstract