拟负刚度磁流变智能隔震系统振动台试验研究

为研究拟负刚度控制算法及磁流变智能隔震系统的有效性和适应性，将自主研发的最大出力为10kN的磁流变液阻尼器(MRFD)安装在隔震层中心，并选取4条有代表性的远近场地震波，峰值加速度由0.1g~0.9g逐步增大，分别对普通隔震结构、输入电流为0A和1A的被动控制结构以及采用基于位移的拟负刚度(DPNS)控制算法的智能控制结构进行振动台试验。通过对结构响应和阻尼器响应的对比分析，研究拟负刚度控制算法的减震效果和磁流变智能控制系统的耗能特性。结果表明：恒定电流为0A的被动控制可同时降低上部结构反应和隔震层位移，但是减震效果有限；恒定电流为1A的被动控制对隔震层位移降低效果明显，但是在多遇地震及远场地震作用下放大了上部结构反应；DPNS控制可同时降低隔震层位移和多遇、设防地震甚至罕遇地震作用下上部结构的反应，且适应于不同的地震动特性；试验中控制系统存在的时滞效应使得DPNS控制力在多遇、设防地震作用下具有较小值，同时罕遇地震作用下具有较强的耗能能力。

Shaking table test of smart isolation system with magneto-rheological damper employing pseudo-negative-stiffness control algorithm

In order to investigate the effectiveness and adaptability of pseudo-negative-stiffness control algorithm and smart isolation systems with magneto-rheological fluid damper (MRFD), a self-developed MRFD with maximum force capacity of 10 kN was installed at the center of base isolation level, and shaking table tests were conducted on four types of structures: conventional base-isolated structure, passive controlled structure with an input current of 0 A, passive controlled structure with an input current of 1 A, and smart controlled structure with displacement-based pseudo-negative-stiffness (DPNS) control algorithm. Each type of structure was subjected to four representative seismic ground motions with far-filed or near-field characteristics and peak ground accelerations (PGAs) varying from 0.1g to 0.9g. Through comparative analysis of the structural response and damper response, the control effect of DPNS control algorithm and energy dissipation characteristics of smart control system with magneto-rheological damper were studied. The experimental results indicate that, in the case of the passive control with input current of 0 A, the superstructure responses and base isolation displacement are reduced simultaneously, while the reduction effect is limited. In the case of the passive control with input current of 1 A, the base isolation displacement is reduced obviously, while the superstructure responses are increased under seismic ground motions with small PGAs or far-field characteristics. The DPNS control can reduce the base isolation displacement and the superstructure responses simultaneously under low-to-median and even extreme seismic excitations, and it can adapt to both far-field and near-field seismic excitations. Because of the time-lag effect of the control system, the DPNS control force shows a small value under low-to-median seismic excitations and a large energy dissipation capacity under extreme seismic excitations.