近场地震作用下采用拉索减震支座桥梁纵向地震响应特性

Influence of Near-Fault Ground Motion Characteristics on Seismic Responses of Continuous Beam Bridges Using Cable-Sliding Friction Aseismic Bearing(CSFAB)

选择台湾集集近场地震记录作为地震动输入,以常规盆式支座和铅芯减隔震支座为对比,系统考察了近场地震动的速度脉冲效应、破裂方向性效应、上盘效应对采用拉索减震支座连续梁桥纵向地震响应的影响,并且对拉索减震支座进行了参数分析。计算结果表明,近场地震三种效应对采用三种支座的连续梁桥的地震响应都有放大效应;拉索减震支座同铅芯减隔震支座比较,对于位移的放大效应有明显的减小,对于在近场强震情况下通常由位移控制的减隔震连续桥梁,突出显示了其限位优势,能够实现力和位移的完美调节;通过调整拉索减震支座的摩擦系数和拉索自由程能达到更理想的减隔震效果,控制结构的位移,防止落梁、碰撞等灾害发生。

The selected seismic input of Taiwan Chi-Chi near-fauh ground motion records are used as input waves. The responses of continuous beam bridges using the cable-sliding friction aseismic bearing（CSFAB） are comprehensively inspected under the consideration of the velocity pulse effect, rupture directivity effect, hanging wall effect in reference of using ordinary pot rubber bearing and lead rubber bearing （ LRB）, including the parametric analysis of CSFAB. The calculation shows that the three near-fault ground motion effects would magnify the seismic responses of continuous beam bridges using three different bearings. Compared with LRB, the alleviation of displacement magnification by CSFAB is obvious. It shows the advantage in controlling displacement and ideal regulation of both force and displacement, considering the fact that the displacement is usually the key in near-fault seismic design of continuous beam bridges. Better isolation effect can be achieved by adjusting the friction coefficient and cable free distance of CSFAB, and thus the displacement can be limited and failure such as unseating and collision can be prevented.