Analysis and optimization of a nonlinear dual‐mode floor isolation system subjected to earthquake excitations
Analysis and optimization of a nonlinear dual‐mode floor isolation system subjected to earthquake excitations
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DOI：
10.1002/eqe.3449
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发表时间：
2021-04
影响因子：
4.5
通讯作者：
P. Bin;M. H. Tehrani;M. Nisa;P. S. Harvey;A. Taflanidis
中科院分区：
文献类型：
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作者：
P. Bin;M. H. Tehrani;M. Nisa;P. S. Harvey;A. Taflanidis
地板隔震系统 (FIS) 用于减轻地震对敏感建筑内容造成的损坏。当大隔离器位移下存在强非线性时，FIS 和主结构 (PS) 之间的动态耦合可能是不可忽略的，甚至是有利的。本研究研究了强震下 FIS 中存在非平滑（类冲击）非线性时 PS 和 FIS 之间动态耦合的影响。使用分量模式分析，通过将线性 PS 的压缩模型耦合到非线性 FIS，开发了 FIS-PS 组合系统的非线性降阶模型。 FIS 假设采用双线性赫兹型接触模型，其中间隙、冲击刚度和阻尼提供参数变化。 FIS-PS 系统的性能通过多目标、基于风险的设计标准进行量化，同时考虑服务级地震下孤立质量所承受的总加速度和最大考虑地震下的层间位移。参数研究的结果有助于了解解耦方法可以可靠地应用于遭受影响的非线性 FIS 的有效范围。还表明，除了在低到中度震动时保护隔离质量之外，还可以通过这种方式调整非线性 FIS，以减轻强震动下支撑 PS 的地震响应。因此，FIS 充当双模式隔振器/减震器系统，具有位移相关响应自适应功能。基于基于风险的随机设计优化，提出了这种双模式系统的优化调整指南。
Floor isolation systems (FISs) are used to mitigate earthquake‐induced damage to sensitive building contents. Dynamic coupling between the FIS and primary structure (PS) may be nonnegligible or even advantageous when strong nonlinearities are present under large isolator displacements. This study investigates the influence of dynamic coupling between the PS and FIS in the presence of nonsmooth (impact‐like) nonlinearity in the FIS under intense earthquakes. Using component mode analysis, a nonlinear reduced order model of the combined FIS–PS system is developed by coupling a condensed model of the linear PS to the nonlinear FIS. A bilinear Hertz‐type contact model is assumed for the FIS, with the gap and the impact stiffness and damping providing parametric variation. The performance of the FIS–PS system is quantified through a multiobjective, risk‐based design criterion considering both the total acceleration sustained by the isolated mass under a service‐level earthquake and the interstory drift under a maximum considered earthquake. The results of a parametric study shed light on understanding the valid range that the decoupled approach can be reliably applied for nonlinear FISs experiencing impacts. It is also shown that the nonlinear FIS can be tuned in such a way to mitigate seismic responses of the supporting PS under strong shaking, in addition to protecting the isolated mass at low to moderate shaking. The FIS, therefore, functions as a dual‐mode vibration isolator/absorber system, with displacement‐dependent response adaptation. Guidelines to the optimal tuning of such a dual‐mode system are presented based on the risk‐based stochastic design optimization.