Predicting Vertical Dynamic Loads Caused by Vehicle-Pavement Interaction

Dynamic loads caused by vehicle-pavement interaction are either moving loads or random loads. Motion property of dynamic loads was described by means of Dirac-delta and Heaviside functions, and its randomness property was studied using a quarter-truck vehicle model. A series of statistical characteristics of wheel loads in frequency domain and time domain are presented in this paper. It was found that dynamic loads are a constant mean Gaussian stationary ergodic process whose power spectral density is in proportion to the power spectral density of pavement roughness, whereas the ratio coefficient relates to dynamic properties of vehicle and velocities of travel. Numerical simulation based on the specifications of the International Organization for Standardization (ISO) indicated that only at low speed could dynamic loads be treated as quasi-narrow band-width random processes, which covers the frequency range of 1.0–4.0 Hz. At high speed, main frequency distributions of dynamic loads occur in 1.0–4.0 and 10.0–15.0 Hz. Further analysis also showed that according to the International Organization for Standardization specifications, the root mean square of dynamic loads is proportional to CSP, the square root of an important index related to pavement levels.