Reliability analysis of suspension bridges against buffeting failure

A reliability analysis of suspension bridges against buffeting failure due to gustiness of wind velocity is carried out using the concept of PRA (probabilistic risk analysis) procedure. For this purpose, the bending stresses at the critical nodes of the bridge deck are obtained for buffeting forces using a spectral analysis technique and a finite element approach. For the purpose of reliability analysis, uncertainties are considered as those arising due to variation of stiffness and mass properties of the bridge, damping, mathematical modeling, flutter derivatives and due to ductility and damage concentration effects. These uncertainties are incorporated by a set of multiplying factors in the limit state function. All multiplying factors are assumed to be independent log-normally distributed random variables. An extensive parametric study is conducted to show the effect of some important parameters on the reliability estimate. The results of the study show that ductility of the system and the structural damping have a significant effect on the reliability against buffeting failure.