Reliability Assessment Framework of the Long-Span Cable-Stayed Bridge and Traffic System Subjected to Cable Breakage Events

As important load bearing members of cable-stayed bridges, stay cables may experience corrosion, fatigue, and accidental or intentional actions that may lead to possible breakage failure. The current bridge design guidelines require that a cable-stayed bridge be designed against single-cable breakage. A holistic reliability assessment framework is developed for a long-span cable-stayed bridge and traffic system subjected to breakage of stay cables considering service load conditions from both traffic and wind. In addition to the bridge structural ultimate limit state, a new bridge serviceability limit state is also introduced by focusing on the overall traffic safety performance of all vehicles of the traffic flow on the bridge following cable breakage incidents. Random variables are defined by considering uncertainties related to structural material properties, sectional properties, traffic, wind condition, and cable breakage parameters. The Latin hypercube sampling technique is adopted to sample the random variables and establish the simulation models by considering various uncertainties of parameters. Nonlinear dynamic analysis is conducted in each experiment to simulate the breakage of stay cables, during which various sources of nonlinearities and dynamic coupling effects from traffic and wind are incorporated. Fragility analyses of the bridge subjected to cable breakage events in terms of the ultimate limit state and the serviceability limit state are finally conducted.