Bridge response with tractor‐trailer vehicle loading

A method for the calculation of dynamic response and loading of single span multigirder bridges due to vehicle loads is described. The analysis takes account of vehicle acceleration or braking, road surface roughness and eccentric placement of the vehicle on the bridge. The analysis is presented for a three‐axle tractor‐trailer vehicle and the bridge is modelled as an orthotropic plate using higher order finite strips. As an example application, the loadings produced with braking of the three‐axle vehicle and a nominally equivalent two‐axle vehicle on a bridge were computed. Previous theoretical studies of bridge loading with vehicle braking had employed a two‐axle idealization of a three‐axle vehicle. The results of the present study show that this approximation is not valid for braking studies as the behaviour of the two vehicle models is significantly different. The loadings produced by a three‐axle vehicle are generally less severe than those due to an ‘equivalent’ two‐axle vehicle.