Structural Analysis of Bridges with Time-Variant Modulus of Elasticity under Moving Loads

A simply supported bridge model is used to investigate the effect of a strain rate dependent modulus of elasticity on the dynamic response of the structure to a moving load. The bridge is modelled as a one-dimensional discretized finite element beam and the moving load is represented by a point force. A constant modulus of elasticity is traditionally employed when simulating the dynamic response of structures under moving loads. In this paper, a time-variant modulus is used to calculate strains and displacements and compare them to the traditional approach for different speeds and bridge spans. The time-variant modulus is obtained from the strain rate of the structure which is used in turn to update the strain at each point in time. The results show significant changes in the modulus and in the resulting load effect as load magnitude and speed increase.