Bridges, Tunnels and other Transportation Structures
Full Session with Abstracts
As important load bearing members of suspension bridges, hangers also experience corrosion, fatigue and accidental vehicle impact, which may cause the reduction of hanger resistance and even possible breakage of hangers. Due to the high flexibility and low structural damping, suspension bridges are susceptible to vibration due to turbulent wind and moving traffic. The bridge structure may become more vulnerable subjected to hanger-breakage scenarios when considerable wind and traffic loads are usually present. The breakage of a single hanger or multiple hangers may further trigger a disproportionately load distribution and lead to cascade failures of individual members or even the whole bridge collapse. It is therefore essential to incorporate interactions with realistic service loads as well as appropriate nonlinear effects for predicting the bridge time-progressive performance following hanger breakage events. Existing studies on suspension bridges subjected to hanger loss events lack appropriate simulation tools to consider both complex dynamic interactions and nonlinearities at the same time. A finite-element based nonlinear dynamic simulation strategy for suspension bridges is introduced to simulate the hanger-loss incidents of the coupled bridge-traffic-wind system. Different from most existing studies, the simulation tool can directly simulate the hanger loss events through nonlinear iteration, during which the breakage of hangers starts at a dynamic initial state on the bridge. Fully coupled interactions among the bridge structure, multiple vehicle dynamic models, and wind excitation are incorporated simultaneously. In the meantime, comprehensive considerations of both geometric and material nonlinearities originated from the structure, aerodynamic loads and cable-loss incidents are incorporated. A prototype suspension bridge is selected to study hanger loss incident as a demonstration. Detailed parametric study is carried out to understand the mechanism of the hanger-loss incidents as well the impacts on bridge response.
By attending the presentation for the study, the audiences will have enhanced understanding of the dynamic performance as well as associated failure risks on suspension bridges from hanger breakage events. The information in this study will help the design professionals to improve the prediction accuracy of bridge performance after hanger-loss incidents and also more rationally assess the potential risk of failure for individual bridge component as well as the whole bridge structure.