EFFECTS OF VEHICLE SUSPENSION DESIGN ON DYNAMICS OF HIGHWAY BRIDGES

The effects of heavy vehicles with leaf-spring and air-spring suspensions on the dynamic response of short-span highway bridges are considered in this paper. The dynamic bridge responses are calculated by modeling the bridge and vehicle separately and combining the models with an iterative procedure. The bridge model is obtained by combining mode shapes with dynamic wheel loads in a convolution integral. This bridge calculation procedure is validated by experiments on two highway bridges. The validated, nonlinear vehicle models consist of a leaf-sprung, four-axle articulated vehicle, and a similar vehicle fitted with air suspensions and hydraulic dampers. These two vehicle models are combined with three different bridge models to predict dynamic bridge responses. Two surface profiles are used on each bridge: a step up at the entrance, and a pseudo-random profile. Dynamic response increments are used to compare the effects of the two vehicles on bridges. The air-suspended vehicle is found to cause significantly lower dynamic bridge responses than the leaf-sprung suspended vehicle.