Reliability-based Analysis and Design Loads for Slender Cable-Supported Bridges Subjected to Cable Loss

拉索突然脱空是缆索承重桥梁的一种极端事件，可能发生在蓄意攻击或拉索损坏的情况下。细长的大跨度桥梁可能同时存在大量车辆或显著的风沿着缆索突然断裂。大多数电缆损失事件突然发生，没有太多的警告时，服务负荷，如交通和风可能存在。在现有的电缆损耗分析中，没有考虑这种极端荷载和使用荷载的组合。目前的荷载抗力系数设计（LRFD）规范没有考虑同时加载。建议的研究是开发一个基于可靠性的动态分析方法，细长的大跨度缆索支撑桥梁组合极端（缆索断裂）和服务负载，如交通和/或风。分析方法的开发沿着以及风洞试验的验证是该项目的一部分。该项目将继续研究缆索支撑的大跨度桥梁在突然失去一根或多根缆索的情况下的响应、安全性和可靠性。由于斜拉桥依靠拉索作为主要支撑元件，因此拉索损失会导致桥梁上的动态载荷，这可能会产生灾难性的后果。将开发各种电缆故障和桥上移动交通的场景，以涵盖实际情况。将对极限状态情况进行非线性分析模拟，并通过风洞中的比例模型实验进行验证（正常移动交通和风是情景荷载的一部分）。该项目的最终目标是在各种实际荷载和事故条件下为大跨度缆索支撑桥梁提供一致的可靠性。该项目的成果将通过出版物传播，并将提供给标准编写机构。

Abrupt cable loss is a critical extreme event for cable-supported bridges, which can happen under intentional attack scenario or deterioration of cables. Slender long-span bridges may have simultaneous presence of a large number of vehicles or significant wind along with sudden breakage of cables. Most cable-loss events occur suddenly without much warning when service loads like traffic and wind may be present. Such combined extreme and service loads have not been considered in the existing cable-loss analyses. The current load resistant factor design (LRFD) specification do not consider simultaneous loading. The proposed research is to develop a reliability-based dynamic analysis method for slender long-span cable-supported bridges under combined extreme (cable breakage) and service loads such as traffic and/or wind. Analytical method development along with validation with wind tunnel testing is part of the project.The project will pursue research in response, safety and reliability of cable supported long-span bridges in case of a sudden loss of one or more cables. The cable loss causes dynamic loads on the bridge which can have catastrophic consequences since cable-stayed bridges depend on cables as the main supporting element. A variety of scenario of cable failure and moving traffic on the bridge will be developed to encompass realistic situations. Non-linear analytical simulation will be developed for limit state situation which will be validated with scale model experiment in wind tunnel (normal moving traffic and wind are part of scenario loading). The ultimate goal of the project is to provide consistent reliability to long-span cable supported bridges under various realistic load and accident conditions. Results of the project will be disseminated through publications as well as will be made available to standard writing bodies.