Dynamics of falling weight deflectometer

An elastodynamic analysis of pavement response to Falling Weight Deflectometer blows is presented. The analysis is based on a Fourier synthesis of a solution for periodic loading of elastic or viscoelastic horizontally layered strata. The method is applied to selected flexible AASHO test sections for which high quality experimental data are available in the literature. The results show that inertial effects are important in the prediction of the pavement response. Conventional static analyses yield significantly different results and, therefore, yield erroneous (unconservative) predictions of pavement moduli back-calculated from deflection data. Elastodynamic analyses, based on fundamental material parameters (Young’s modulus, mass density) appear to provide a useful vehicle for correlating pavement response between different loading modes (impulse, vibratory, etc.). Since resonance is a less important factor in the displacement response characteristics of pavements subjected to transient loading, deflection data obtained from transient loading devices are in general easier to interpret.