长周期长持时强震下铅芯橡胶隔震结构动力性能演化及失效控制研究

With the rise of loading cycles on lead rubber bearings, temperature of lead core in bearings will increase and the mechanical performance of lead rubber bearings will be degenerated under real-time reciprocating large-displacement loading of which frequency is basically equal to frequency of isolated structure. Then, yield force of lead rubber bearings will decrease and ability of energy dissipation of bearings will be reduced. Even the lead core finally appears smashing damage, becomes lead powder and loses shear strength. Thereby the displacement at isolated layer of structure will be larger and isolated structure will be failure under strong earthquake with long period and duration. Therefore, this project is aimed to study effect of mechanical performance degradation of lead rubber bearings on isolated structure under strong earthquake with long period and duration by using the degenerative mechanical model obtained by real-time reciprocating large-displacement testing, and dynamic performance evolvement and failure rules of isolated structure is obtained. A new high damping rubber passive control device is developed for controlling the displacement failure at isolated layer and the nonlinear mechanical model of this passive control device is presented. Then, according to nonlinear mechanical model, the control strategy for failure of displacement at isolated layer is discussed, and optimum parameter of passive control device is obtained by the method of random parameter optimization. Real-time hybrid testing for isolated structure and controlled isolated structure are carried out by adopting full-scale lead rubber bearings and passive control device, and dynamic performance evolvement and failure rules of isolated structure is obtained by testing. Finally, practical design method for isolated layer of isolated structure with lead rubber bearings under strong earthquake with long period and duration is presented. The findings of the project provide the theoretical and practical foundation for earthquake safety of isolated structure.

铅芯橡胶隔震支座在实时（加载频率与结构频率基本相同）往复大变形荷载作用下，随着加载次数的增加，铅芯温度升高，力学性能退化，屈服力降低，造成支座耗能能力降低，甚至极端情况下铅芯发生粉碎性破坏，变成铅粉，失去承载能力，从而导致隔震结构在长周期长持时强震作用下隔震层位移过大，造成隔震结构失效。本课题通过建立实时往复大变形下铅芯橡胶隔震支座力学退化模型，研究其力学性能退化对隔震结构在长周期长持时强震作用下影响，得到其动力性能及失效演化规律；研制控制层位移失效的高阻尼橡胶被动控制装置，建立其非线性力学模型，探讨控制隔震结构失效的策略；通过参数随机优化，获得控制隔震层失效控制装置的最优参数；采用足尺铅芯橡胶隔震支座进行隔震结构和受控隔震结构实时混合试验，通过试验获得隔震结构动力性能演化及失效规律；提出长周期长持时强震作用下铅芯橡胶隔震结构隔震层实用设计方法。研究为隔震体系的地震安全提供理论与应用基础。

铅芯橡胶隔震支座在实时往复大变形荷载作用下，随着加载次数的增加，铅芯温度升高，力学性能退化，屈服力降低，造成支座耗能能力降低，甚至极端情况下铅芯发生粉碎性破坏，变成铅粉，失去承载能力，从而导致隔震结构在长周期长持时强震作用下隔震层位移过大，造成隔震结构失效。本课题通过采用足尺铅芯橡胶隔震支座以及接近足尺铅芯橡胶隔震支座，进行多次不同大变形下实时加载水平力学性能试验，基于义Bouc-Wen模型，通过遗传算法将力学模型与试验曲线进行拟合修正，建立实时往复大变形下铅芯橡胶隔震支座力学退化模型。然后，研究了力学性能退化对隔震结构在长周期长持时强震作用下影响，得到其动力性能及失效演化规律，考虑铅芯性能退化对隔震层的影响较大， 这会对上部结构产生整体倒塌的风险。因此在长周期长持时地震作用下，需要考虑铅芯退化对隔震结构的影响。.研究长周期长持时强震作用下隔震结构失效控制策略，研发两种针对隔震层失效的被动控制装置：新型柔性弹性限位防护装置和柔性弹塑性限位防护装置，通过对足尺柔性限位装置有限元仿真分析和压缩性能试验，提出了其相应的力学模型。建立考虑性能退化的铅芯橡胶隔震支座、具有非线性力学性能的控制装置和上部结构的一体化分析模型，研究了其相应的减震效果。应用概率密度演化方法，研究了抗震结构、基础隔震结构和限位基础隔震结构的随机响应和动力可靠度，结果表明，采用限位后，可有效提高隔震结构的动力可靠度；然后基于遗传算法对隔震层失效控制装置进行多目标一体化优化设计，获得了失效控制装置参数的最优解集；然后进一步搭建了隔震实时混合实验平台软件和硬件系统，完成了强震作用下隔震结构性能评估。最后，建立长周期长持时强震作用下铅芯橡胶隔震结构隔震层实用设计方法。本项目已发表学术论文24篇，其中SCIJCR一区论文4篇，EI论文8篇。研究成果为考虑长周期长持时强震或超烈度地震作用时隔震结构科学设计与推广应用提供科技支撑。