多维地震作用下隔震桥梁地震反应(Ⅱ)——理论分析与试验结果比较

SEISMIC RESPONSE OF ISOLATED BRIDGES WITH LRB UNDER MULDI-DIRECTIONAL EARTHQUAKE——PART (Ⅱ) THEORETICAL AND COMPARATIVE ANALYSIS

为了研究铅芯橡胶支座(LRB)隔震桥梁在双向水平地震激励下的非线性地震反应,首先用Bouc-Wen模型模拟水平正交两向作用力条件下LRB支座非线动力行为的双向恢复力特性。在此基础上,提出一种双向水平地震激励下多跨连续隔震桥梁的非线性地震反应分析模型以及求解方法,并通过隔震连续梁桥结构模型振动台试验证实了所建立双向多自由度计算模型的正确性,以及铅芯橡胶隔震支座两水平方向力变形相互耦合作用模型的合理性。因此,对隔震桥梁LRB支座进行设计时,建议考虑支座恢复力的相互耦合作用;多维地震动输入时,特别是竖向地震分量较大时,进行橡胶支座设计时应考虑铅芯橡胶支座上有竖向拉力产生的情况。

In order to investigate the nonlinear seismic responses of isolated bridges with lead rubber bearings (LRB) under multi-directional horizontal earthquake excitation, Bouc-Wen model of LRB under two horizontal orthogonal directional excitation is adopted. Based on this model of LRB, an analytical model of nonlinear seismic responses of a continuous multi-span isolated bridge with LRB and its solving method are carried out. The multi-degrees-of-freedom mathematical model of the seismically isolated bridge is proved to be right and the bi-directional coupled Park model of LRB is proved to be reasonable by the shaking table tests of the continuous girder isolated bridges model with LRB. It should consider the bi-directional coupled interaction of the restoring forces of LRB, which has considerable effects on the seismic responses of the isolated bridge. Vertical tension of LRB should be considered if vertical earthquake amplitude is greater in isolator design.