考虑约束体系变化的独塔斜拉桥抗震性能研究

Research on Seismic Performance of Single-pylon Cable-stayed Bridge Considering the Change of Constraint System

以跨径为268 m+213 m+85 m的独塔斜拉桥——东江特大桥为研究对象,通过基于IDA分析的能力需求比法,研究了不同地震峰值加速度(PGA)下关键装置损伤引起的结构体系变化对桥梁抗震性能的影响,并进一步探究了不同约束体系下结构关键构件的损伤顺序及破坏机理。研究结果表明,不同PGA下,支座失效会引起结构约束体系变化,改变斜拉桥的传力途径,对结构抗震性能有重要影响,整体表现为由结构内力响应向位移响应的过渡;支座作为斜拉桥传力的关键部件,应保证支座固定方向的承载能力具有较高的安全储备,活动方向具备充足的容许位移;对预期破坏的分级支座,应保证支座在各静动力荷载工况下能够正常工作,避免体系变化对桥梁结构抗震性能产生显著影响。

In this paper,the Dongjiang Bridge which is a single pylon cable-stayed structure and 268m+213m+85min span layout is taken as the research object,based on IDA analysis,the effect of structural system changes caused by damage of key devices under different peak seismic acceleration(PGA)on the seismic performance of the Bridge is studied,and the damage sequence and failure mechanism of key structural members under different constraint systems are further explored.Results show that,under different PGA,the failure of support will cause the change of the structural constraint system and the force transmission path,and have an important impact on the seismic performance of the structure,which is manifested as the transition from internal force response to displacement response.As the key component of force transmission of cable-stayed bridge,the bearing capacity of the support in the fixed direction should be ensured with high safety reserve and the moving direction should have sufficient allowable displacement.For the graded supports that are expected to be damaged,the normal operation of the supports under different static and dynamic loads should be ensured to avoid the significant impact of system changes on the seismic performance of the bridge structure.