On Sensitivity of Time Step for Dynamic Analysis of Bridges under Moving Loads
For engineers analyzing railway bridges, this provides a practical guideline for selecting time steps to ensure accurate dynamic responses.
This study investigates the effect of time step selection on the dynamic analysis of railway bridges under high-speed moving loads, proposing an equation to determine the proper time step based on bridge span length and vehicle speed.
In the analysis of structures under dynamic loads, selection of a proper time step has a great influence to reach exact results. In this research determination of proper time step in dynamic analysis of railway bridges under high speed moving loads is considered. Dynamic responses of four simple span steel bridges with 10, 15, 20 and 25 meter length to moving trains with speed from 100 to 400 km/h and axle distances from 13 to 23 meter are calculated considering different time steps in analysis. The results indicate that by increase in moving speed of vehicle (increase in loading speed) the length of proper time step for dynamic analysis is reduced. In contrast by increase in span length (increase in bridge vibration period) longer time steps can be used in dynamic analysis. In this research by investigation of dynamic analysis results, an equation is suggested for determination of proper time step for dynamic analysis of bridges under moving loads.