基础隔震结构在近断层水平-竖向地震联合作用下的动力响应

Seismic Response of Base-isolated Structures Under the Combined Action of Horizontal and Vertical Components of Near-fault Ground Motions

隔震结构在中远场常规地震作用下表现良好,而在近断层地震作用下,其隔震效果可能有所降低。一方面,由于近断层地震水平分量富含长周期速度脉冲,隔震支座可能发生较大水平位移;另一方面,近断层地震竖向加速度峰值较大,会导致隔震支座竖向力发生较大变化,使其水平刚度有所降低,严重时发生屈曲失稳,或者受拉破坏。考虑到隔震结构是由隔震支座和上部结构串联而成,隔震支座的动力响应和破坏模式将直接影响上部结构动力响应,所以,本文在ABAQUS软件中建立隔震结构非线性有限元模型,使用Koh-Kelly力学模型考虑隔震支座水平和竖向力学性能的相互耦合,进行隔震结构在近断层水平–竖向地震联合作用下的动力响应分析,评估不同隔震层参数对隔震结构动力响应的影响。

Base-isolated structures show excellence performance under far-field earthquake. However, when subjected to near-fauh ground motions, the isolation effects may be reduced to some extent. On one hand, the horizontal component of near-fault ground motions may lead to large horizontal displacements in the isolation layer. On the other hand, the large vertical acceleration of near fault ground motions will lead to significant variation in the vertical load of the bearings, which may lead to decrease in its horizontal stiffness. In extreme circumstance, the bearings may buckle under pressure or experience tensile damage. Considering that based isolated structures are assembled by isolation bearings and superstructures in series, the dynamic response and failure pattern of the bearings will significantly affect the dynamic response of the structure. In the view of this, nonlinear finite element model of base-isolated structures are built in ABAQUS software in this paper. The coupling effects of the bearings are simulated by Koh-Kelly model. Then dynamic response analysis are conducted to investigate the effects of different isolation parameters on the dynamic response of the base-isolated structures.