Total Load Effects of Portal Frame Bridges in High-Speed Railway Lines

This paper studies the maximum total load effects of short span portal frame railway bridges when traversed by high-speed trains. It is generally assumed that in single span bridges the maximum stresses, displacements and accelerations occur at the mid-span section. However, this in not necessarily correct and the maximum might be located in a wide area around the mid-span. This study aims to quantify the underestimation of the mid-span assumption when calculating maximum load effects. A numerically validated 2D Vehicle-Bridge Interaction model is used to analyze the stresses, displacements and accelerations that develop during the passage of high-speed trains. These load effects are studied along the full length of the structure and compared to the maximum obtained at the mid-span section. Particular attention is given to the resonant speeds near the operational speeds of high-speed railways. The results show that significantly higher load effects can be expected. The presented study is the preliminary work for deciding on the optimum configuration of empirical field tests.