Analytical dynamic impact study based on correlated road roughness

The dynamic behavior of multigirder bridges under heavy trucks is investigated based on correlated road surface roughness. Four prestressed concrete bridges with span lengths ranging from 9.14 to 42.67 m (30 to 140 ft) are modeled as grillage beam systems. 3D nonlinear mathematical models for typical trucks are developed based on weigh-in-motion measurement data. These data were collected at two stations located on interstate highway 75 and 95, respectively, for a period of one week. There are a total number of truck counts of 21,444 processed in this study. The longitudinal road surface roughness is generated as correlated random processes along the deck transverse direction. Based on the results from field measurements, the spatial coherence function of these roughness profiles is approximately taken as a constant. Analytical results indicate that (1) the mean values of dynamic impact factors induced by heavy trucks are generally less than the values specified by the American Association of State Highway and Transportation Officials Specifications; and (2) the impact factors generally increase with the coefficient of correlation of road surface roughness.