带有复合摩擦阻尼系统的基础隔震结构分析

摘要

针对常规摩擦阻尼器的起滑力难以确定的问题,提出了复合摩擦阻尼系统(CFDS),它由非线性硬弹簧和摩擦阻尼器串联而成.当地震较小时,摩擦阻尼器处于附着状态,非线性硬弹簧发挥作用,防止隔震层位移过大；当地震较大时,非线性硬弹簧的变形则保持不变,摩擦阻尼器处于滑动状态,通过摩擦阻尼耗散能量.建立了带有复合摩擦阻尼系统的基础隔震结构的运动方程,指出摩擦阻尼器处于附着和滑 移2种状态下边界条件.据此研究了常规强震和近断层脉冲型地震动作用下复合摩擦阻尼装置对橡胶隔震结构的减震效果.仿真分析表明:安装复合摩擦阻尼系统,在显著降低隔震层位移的同时,对上部结构的层间位移和加速度均有一定的减震效果；并且,在整个运动过程中,摩擦阻尼器会在附着和滑移2种状态之间来回切换.详细研究了复合摩擦阻尼系统的3个参数对隔震结构的减震效果.结果表明:在不同地震波作用下,由于摩擦阻尼系统参数的变化导致隔震结构地震响应的变化趋势是不同的,因此最优参数的取值与输入地震波类型和地面加速度峰值有关,并且不存在使隔震层位移和上部结构加速度同时达到最小的最优参数,因此需要设定合适的控制目标以确定适当的阻尼系统参数.%It is hard to decide the initial slip force of normal friction damper.In order to solve this problem,a novel composite friction damping system (CFDS) is formed by connecting a nonlinear hard spring and a friction damper in series.When the earthquake intensity is smaller,the friction damper is in a state of adhesion,and nonlinear hard spring undergoes deformation to prevent the isolated layer from large drift.When the earthquake intensity is larger,the deformation of the hard spring keeps constant,while the friction damper is slip and friction damping occurs to dissipate seismic energy.The motion equations of base isolated structure with the proposed damping system are derived,and boundary conditions aimed at two different phases,stick and slip,of friction damper are pointed out.Then seismic response of the base isolated structure subjected to normal far-field earthquakes and near-fault pulse-like ones are studied.Compared with structures only installed with isolator devices,numerical simulation shows that CFDS can effectively suppress the horizontal motion of isolated layer.If the parameters of the damping system are proper,the interstorey drift and acceleration of the main structure are also reduced.Furthermore,the state of the friction damper in CFDS will switch between stick status and slip status.The influence of three parameters of the proposed damping system is also investigated in depth.It is pointed out that,since the seismic response change trend of the base isolated structure caused by the variation of CFDS parameters depends on earthquake type,optimal parameters of the CFDS is related to the peak ground acceleration and type of the earthquake,and the optimal parameters,which minimize both displacement and acceleration response of the superstructure,is not exist.So only when the proper control goal is given,the proper parameters of CFDS can be selected.