Fatigue Stress Analysis of Suspension Bridged using FEM

Fatigue is an important fallurc mode for large suspension bridges under traffic loadings. However, large suspension bridges have so many attributes tbat it is difficult to analyze their fatigue damage using experimental measurement methods. Numerical simulation is a feasible method of studying such fatigue damage. In British standards, the finite element method (FEM) is recommended as a rigorous method for steel bridge fatigue analysis. This paper aims at developing a model of a large slispension steel bridge using finite element methods (FEM) for fatigue stress analysis. The Tsing Ma Bridge (TMB) is selected for a case study and the corresponding finite element model is presented. The verification of the model is carried out with the help of the measured bridge modal characteristics and the online dala measured by the structural health moniloring system installed on the bridge. The results show that the constructed FE model is efficient for bridge dynamic analysis. Global structural analyses using the developed FE model are presented to determine the components of the nominal stress generated by railway loadings and some typical highway loadings. The critical locations in the bridge main span are also identified with the numerical results of the global FE stress analysis. It could be seen that the FE model could be served as a basis for evaluating fatigue damage and the remaining life of the bridge could then be evaluated