Analytical Modeling of Bridge-Road-Vehicle Dynamic Interaction System

Abstract

We present a three-dimensional (3D) dynamic model for the bridge-road-vehicle interaction system. A slab-on-girder bridge is modeled as a grillage system subjected to multiple moving truck loads. Multi-axle semi-tractor-trailer is idealized as a 3D vehicle model with a nonlinear tire-suspension system, having eleven independent degrees of freedom. Road roughness profiles are generated from the random Gaussian process as well as limited measurements of actual road profiles. Truck wheel loads are applied at any point and then transferred to nodes as equivalent nodal forces. The Newmark-\#946; integration method is applied as a numerical algorithm for solving the bridge-road-vehicle dynamic interaction equations. The major parameters affecting the bridge dynamic response (or the dynamic load factor) include road roughness, truck weight, speed and mechanical properties of the tire-suspension system and bridge stiffness and boundary conditions. Results from other dynamic models as well as field tests are compared with those from the current 3D model. The results show that the dynamic load factor is highly dependent on road roughness, vehicle suspension, and bridge geometry.