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为了减小底层柔性结构的地震反应,防止结构因底层位移过大而倒塌,提出了一种底层柔性结构减震控制体系,在柔性底层安装磁流变阻尼器对其实施半主动控制。考虑到竖向地震的不利影响,建立了结构在双向耦合地震作用下的动力分析模型和振动控制方程,采用LQR控制算法对结构进行地震反应分析。研究表明,在无控情况下,结构的位移主要集中在底部柔性层;实施半主动控制后,结构的底层位移、顶层位移、各层加速度和倾覆力矩均明显减小,其中底层位移减小60%以上。在耦合地震作用下结构的地震反应比单纯水平地震作用下有所增加,以倾覆力矩的增加最明显,因此在高烈度地区应该考虑竖向地震对结构的影响。层间刚度比对结构的控制效果也会产生较大的影响,结构层间刚度比的确定应该在底层位移、顶层加速度和倾覆力矩之间权衡考虑。考虑土与结构相互作用会使结构的控制效果降低。
In order to reduce the seismic response of the bottom flexible structure and prevent the structure from collapsing due to the excessive bottom displacement, a damping control system of the bottom flexible structure is proposed. The MR damper is installed on the flexible bottom to implement semi-active control. Taking into account the adverse effects of vertical earthquake, the dynamic analysis model and the vibration control equation of the structure under the bidirectional coupling earthquake are established. The seismic response analysis of the structure is carried out by LQR control algorithm. The results show that under uncontrolled conditions, the displacement of the structure mainly concentrates on the bottom flexible layer. After the semi-active control is implemented, the displacement of the bottom layer, the displacement of the top layer, the acceleration and overturning moment of each layer are obviously reduced, and the displacement of the bottom layer is reduced by 60 %the above. The seismic response of the structure under coupling earthquake is increased more than that of the simple horizontal earthquake so that the overturning moment increases most obviously. Therefore, the influence of vertical earthquake on the structure should be considered in the area of high intensity. The effect of interlayer stiffness on the control effect of the structure will also have a greater impact. The determination of the stiffness ratio of the structural layers should be considered between the bottom displacement, top acceleration and overturning moment. Taking into account the interaction of soil and structure will reduce the control effect of the structure.