Framework of Nonlinear Dynamic Simulation of Long-Span Cable-Stayed Bridge and Traffic System Subjected to Cable-Loss Incidents

摘要

Cable loss is a critical extreme event for cable-supported bridges, which sometimes governs the bridge design. Like most extreme events possibly occurring on long-span bridges, cable loss (breakage) may happen with service loads such as traffic and/or wind applied to the bridge simultaneously. Dynamic analysis incorporating critical interactions with realistic service loads as well as appropriate nonlinear effects becomes essential for predicting the time-progressive performance of the bridge following cable-loss incidents. Despite the recent progress on related topics, existing studies on long-span bridges often suffer from the lack of appropriate simulation tools to address the needs of both complex dynamic interactions and nonlinearities associated with cable-loss incidents at the same time. A finite-element (FE) based nonlinear dynamic simulation framework for long-span bridges is developed to simulate the cable-loss incidents of the coupled bridge-traffic-wind system. Different from most existing studies, firstly, such a simulation tool directly simulates the cable-breakage event by both applying the counteracting forces and also physically reducing the area of the failing cable within the total breakage duration. As a result, both the elemental configuration and force condition during a general cable-loss incident can be characterized more realistically than existing studies. Secondly, the fully-coupled interactions among the bridge structure, multiple-vehicle dynamic models, and wind excitation are simulated on the FE basis. Lastly, comprehensive considerations of both geometric and material nonlinearities originated from structure, aerodynamic loads, and cable-loss incidents are incorporated. A prototype long-span cable-stayed bridge is selected to demonstrate the investigation of single-cable loss incidents. A detailed parametric study is carried out to understand the mechanism of the cable-loss incidents as well the impacts on bridge response. (C) 2015 American Society of Civil Engineers.