Stress Analysis of a Long-Span Steel-Truss Suspension Bridge under Combined Action of Random Traffic and Wind Loads

Abstract

This paper presents an efficient approach for dynamic stress analysis of a long-span bridge under the combined action of stochastic traffic and wind loads based on the stress influence function, which converts the stress finite-element analysis problem into a problem of stress integral or summation. The Aizhai Bridge in China is used as an example to demonstrate the numerical procedure for the stress analysis. First, the finite-element model for the Aizhai Bridge is established, and the critical locations of the bridge are determined by refined analyses. By using influence line analysis, the stress influence functions to calculate the dynamic stress response of the bridge under random traffic and wind loads are obtained through segmented polynomial fitting. Second, the random traffic flow simulation program is compiled by adopting the Monte Carlo–simulation method. The moving equivalent dynamic vehicle loading, representing different types of running vehicles on the bridge, is calculated based on the full interaction analyses of a single-vehicle–bridge–wind system, and the database of the equivalent vehicle load is established. Finally, the stress induced by the combined action of the random traffic and wind loads is obtained by summing the product of the stress influence surface function and equivalent vehicle loads and by integrating the product of the stress influence line functions and wind loads where the dynamic effect is considered by introducing the dynamic influence coefficient. The proposed method is validated by comparing the results with those from analysis with commercial software, and it is found that that the proposed method is feasible and efficient.