Study of dynamic impact factors of two-track continuous and integral railway bridge subjected to high-speed loads

The impact factor (IF) assessment of a four-span non-prismatic continuous and an equivalent integral railway bridge under the action of high-speed moving train loads is conducted in this study. Critical analysis of the full-scale three-dimensional finite element (FE) bridge models is done to investigate the differences in the IFs of all the spans of the two-track railway bridge under various loading conditions. A simplified approach is proposed to identify the dynamic IF values. The results show that for a continuous bridge, with the increase in the load on the bridge, IF coefficients reduce from 0.195 to 0.102. However, for the integral bridge, and considered loading conditions, almost similar IF coefficients (0.100) are obtained. For the intermediate spans, the resonance phenomenon for the integral bridge is achieved at lower speeds compared to the equivalent continuous bridge.