Fatigue reliability analysis of multi-loading suspension bridges considering nonlinear accumulative damage

Taking into account uncertainties in the nonlinear process of fatigue damage accumulation for fatigue reliability analysis of multi-loading long-span bridges, a fatigue reliability assessment method for a long suspension bridge under combined highway, railway, and wind loadings was proposed using a continuum damage model (CDM). First, the CDM based on continuum damage mechanics was briefly introduced, and main model parameters were analyzed. Then, a simplified CDM was proposed for further application to bridge structures. A limit state function for fatigue reliability analysis based on CDM was defined by introducing proper random variables into the CDM. The Monte Carlo simulation (MCS) was adopted to generate the random variables and to calculate the failure probability. Finally, the Tsing Ma Bridge in Hong Kong was taken as a case study, and the failure probabilities of the bridge at the end of 120 years were estimated for different loading scenarios. The results indicate that the health condition of the bridge in fatigue is satisfactory under the current traffic conditions, but attentions should be paid to future traffic growth because it will largely accelerate the damage growth.