挡块对斜拉桥横向抗震体系的影响

Influence of side retainers on transverse anti-seismic system in cable-stayed bridge

为探讨挡块限位装置对斜拉桥横向抗震体系的影响,以宁波大榭二桥为工程背景,采用非线性时程法分析比较了三种状况下斜拉桥的结构地震响应,即不考虑挡块的作用、考虑挡块的影响、挡块破坏后的效应等三种情况。研究表明:梁体与挡块的碰撞效应有利于改善斜拉桥在地震作用下的横向受力,降低控制横向设计的锚墩的响应需求;而挡块的破坏则会导致梁体侧向过大的位移,带来结构稳定和疲劳方面的隐患;通过在边墩和锚墩设置粘滞阻尼器可以改善结构的受力、限制梁体的侧移并使支座免于破坏,但增加了设计困难和建设造价,而设置足够强度的挡块值得推荐。

Under the background of Daxie Bridge in Ningbo,the effect of side retainers on the lateral anti-seismic system in cable-stayed bridge was investigated.Nonlinear time history analysis was utilized to obtain the seismic responses of Daxie Bridge in correspondence with three conditions,i.e.structural response excluding retainer influences,structural response incorporating retainer influences,and structural response considering the effects of damage of retainers.It is found that the pounding effects between girder and retainer are effective to reduce the earthquake response of the auxiliary piers,which usually governs the design of cable-stayed bridges in the transverse direction.Damage of retainers will amplify the lateral displacement of the girder,which is not expected to happen for cable-stayed bridges.The retainers are efficient to diminish the seismic response of bridge structure,to restrain the displacement of girder and to protect the bearings from earthquake when dampers are mounted on the side piers,which will,however,increase the cost and cause design problems.Recommendations were made to choose strong retainers with sufficient strength to survive severe ground motions as a useful measure for cable-stayed bridge.