Dynamic load allowance for highway bridges
University of New Brunswick
Dynamic response of highway bridges under traffic loads is an important design consideration in bridge engineering. Design codes simplify the dynamic analysis by scaling the live load using the dynamic load allowance parameter. In Canada, the dynamic load allowance, recommended by CSA S6:19 is based on dated testing and simplified analysis. In this thesis, a coupled vehicle-bridge interaction model is derived and validated to study the bridge live load interaction. The model represents the bridge as a series of Timoshenko beam elements with lumped masses. The vehicle is modelled as a system of rigid masses on an elastic suspension. The parametric study focuses on vehicle characteristics, velocity, pavement roughness, bridge configurations, and bridge material properties. It was found that lighter trucks tend to produce higher amplification values, as does higher velocities. The effects of vehicle suspension were negligible, as was road roughness and material properties under certain circumstances.