大跨度中承式钢桁拱桥抗震性能分析

为研究大跨度中承式钢桁拱桥在地震作用下的地震响应以及减隔震措施,以主跨436 m的中承式钢桁拱桥——广州明珠湾大桥为背景,利用MIDAS Civil软件建立主桥空间有限元模型,采用反应谱法计算罕遇地震作用下的地震响应并进行抗震性能分析;选择双曲面球型减隔震支座作为减隔震措施,采用非线性时程分析方法计算罕遇地震作用下的地震响应,对比设置减隔震措施前、后抗震性能进行减隔震效果评估。结果表明:该桥自振基本周期长,罕遇地震作用下结构动力响应较大,桥墩桩基不能满足抗震性能要求;设置双曲面球型减隔震支座后,各向地震作用下大部分结构的内力响应均明显减小,其中桩基安全系数提高66%,改善了大跨度中承式钢桁拱桥的抗震性能,结构满足抗震要求。

Seismic Performance Analysis of Long-Span Half-Through Steel Truss Arch Bridge

The Mingzhu Bay Bridge,a half-through steel truss arch bridge with a main span of 436 m,is used as a case to study the seismic responses of the long-span half-through steel truss arch bridge under seismic actions and verify the seismic mitigation and isolation measures.Spatial finite element models of the main bridge were established by MIDAS Civil to compute the seismic response of the bridge under rare earthquakes and conduct seismic performance analysis,using the response spectrum method.Spherical bearings with double curved surfaces are installed for seismic mitigation and isolation.The seismic responses of the bridge under rare earthquakes were computed by the nonlinear time-history analysis method,and the seismic performances of the bridge before and after installation of spherical bearings were compared to evaluate the seismic mitigation and isolation effect of the bearings.The results show that the natural periods of the Mingzhu Bay Bridge were long,which exhibited strong dynamic responses to rare earthquakes before the installation of spherical bearings,and the pile foundations of piers could not meet the seismic resistant requirements.Whereas with spherical bearings,the internal force responses of the majority of bridge components are remarkably reduced under the seismic motions in varying directions.The safety factors of pile foundations are improved by 66%,leading to great enhancement of the seismic performance of the long-span half-through steel truss arch bridge,and the bridge structure can also meet the seismic performance requirements.