弹塑性索和黏滞阻尼器系统用于斜拉桥横向减震分析

Elastoplastic cable pair and viscous damper used in the lateral seismic isolation of cable-stayed bridges

旨在研究弹塑性索对与黏滞阻尼器组合减震系统用于大跨度斜拉桥横向抗震设计作用。依据Caltrans规范构建了弹塑性索对的非线性本构关系,基于永宁黄河大桥弹性索对与黏滞阻尼器组合减震系统设计,通过调增地震波幅值,使弹性索进入塑性状态并分析结构响应。研究结果表明:容许拉索进入塑性可以显著增加其变形能力,进而提高整个结构应对强震作用的能力;与塔梁固定的常规体系相比,引入弹塑性索与黏滞阻尼器组合体系可以大幅降低主塔塔底弯矩及主梁加速度响应;与理想弹性索对工况相比,采用弹塑性索对虽然会导致较大的主梁残余位移,但对于控制最大索力和改善主梁加速度响应效果明显,同时塔梁、墩梁最大相对位移和塔底弯矩基本不变。

The feasibility of utilizing the elastoplastic cable pair and viscous damper in the seismic isolation of long span cable-stayed bridges was evaluated. A nonlinear constitutive model for the elastoplastic cable pair was developed based on the Caltrans standard. Through linearly increasing the excitation intensity, the responses of the Yongning Yellow River Bridge were analyzed, where the elastic cable pair and viscous damper were successfully applied in lateral seismic control, and the cable pairs were forced to enter into an inelastic phase. The results show that the deformation capacity of cable pairs can be greatly enhanced if certain plastic behavior is allowed and consequently the ability of the structure against strong earthquakes can be significantly improved. In comparison with the conventional system with fixed transverse girder-tower connections, the utilization of elastoplastic cable pair and viscous damper can substantially reduce the base bending moment response on pylon and the acceleration response of girder. When compared with the hypothetic case with ideal elastic cable pair, though the residual displacement of the girder is relatively larger, the maximum transmitted force of the cables and the acceleration of the girder can be well controlled, while the relative displacements at the tower and piers and the base bending moment on tower columns maintain almost unchanged.