Life-cycle failure probability analysis of deteriorated RC bridges under multiple hazards of earthquakes and strong winds

Engineering structures may be exposed to one or more extreme hazards during their life-cycles. Current structural design specifications usually treat multiple hazards separately in designing structures and there is a limited probabilistic basis on extreme load combinations. Additionally, the performance of engineering structures will be deteriorated by the aggressive environments during their service periods, such as chloride attack, concrete carbonation, and wind-induced fatigue. This study presents a probabilistic methodology to assess the time-dependent failure probability of RC bridges with chloride-induced corrosion under the multiple hazards of earthquakes and strong winds. The loss of cross-section area of reinforcements and the reduction in strength of reinforcing steel and concrete cover induced by the chloride attack are considered. Moreover, the Poisson model is employed to obtain the occurrence probabilities of the individual and concurrent earthquake and strong wind events. The convolution integral is used to determine the joint probability distribution of combined load effects under simultaneous earthquakes and strong winds. Numerical results indicate that the structural failure probability under multiple hazards increases significantly during the bridge′s life-cycle due to the chloride corrosion effect. The contribution of each hazard event on the total structural failure probability varies with time. Thus, neglecting the combined influences of multiple hazards and chloride-induced corrosion may bring erroneous predictions in failure probability estimates of RC bridges.