近断层地震作用下层间隔震结构隔震层软限位减震研究

Isolation technology is effective to mitigate earthquake disaster. The research results under far-field ground motion were written into the Code for Seismic Design of Building (GBJ50011-2010). For the past few years, the recodes of near-field ground motion were obtained and studied more. It is found that the characteristics between near-field and far-field ground motion are different. The velocity-pulses and displacement-pulses which possess large amplitude and long period will bring about large deformation and instability to isolation layer. The safety of isolation layer is the precondition which the isolation technology plays to utility. The scheme of soft limiting deformation which protects isolation layer of inter-story isolation building is proposed. The limiting devices are installed into isolation layer, which can limit deformation of isolation layer and reduce dynamic response of superstructure and substructure as far as possible. The reserve space between limiting devices and isolation layer can ensure the effect of isolation to frequent earthquakes. Limiting devices have the advantages of simple construction and low cost. The theoretical analysis and shaking table model test under near-field ground motion will be carried out. The main characteristic parameters of near-field ground motion will be provided. The limiting deformation principle and optimum design method of soft limiting inter-story isolation buildings would be put forward. The research objective is the key problem which needs to be solved urgently to inter-story isolation technology under near-field ground motion, which is development and perfection to isolation technology and possesses long-term economic benefit and social effect.

隔震技术能有效减轻震害，远场地震作用下的研究成果，已编入《建筑抗震设计规范》（GBJ50011-2010）。近年来，随近断层地震动记录增多，研究发现其运动特性不同于远场地震动，大幅值、长周期的速度与位移脉冲会使隔震层产生过大变形，导致隔震支座侧倾失稳。而隔震层安全是隔震技术发挥效用的前提。本项目对层间隔震提出隔震层软限位保护方案。该方案在隔震层安装限位装置，限制隔震层变形，同时尽可能降低上、下部结构动力响应；限位装置与隔震层之间预留距离，可不影响小震隔震效果；限位装置构造简单，造价低。通过近断层脉冲型地震作用下层间隔震结构隔震层软限位与不限位的理论分析，以及振动台模型实验，给出近断层地震动主要特征参数，层间隔震结构隔震层软限位减震机理，提出软限位层间隔震结构体系优化设计方法。本项目的研究，是近断层地震作用下层间隔震技术亟需解决的关键问题，是对隔震理论的发展与完善，具有长远的经济与社会效益。

近断层地震动运动特性不同于远场地震动，大幅值、长周期的速度与位移脉冲会使隔震层产生过大变形，导致隔震支座侧倾失稳。本课题分析了近断层地震动特征参数对层间隔震结构动力响应的影响，对层间隔震结构隔震层软限位进行了研究，主要结论如下。.提出了影响层间隔震结构地震响应的近断层地震动主要特征参数。近断层地震动的输入能、PGV、PGA、PGV/PGA、PGD、断层距、Tp/T1与结构动力响应参数的相关程度较显著，选取近断层地震动记录不能仅考虑PGA，还应考虑相关性较强的其他参数。.对弹簧与U型钢板限位装置进行了力学性能实验研究。给出了U型钢板限位装置的弹性刚度、塑性刚度、卸载刚度、最大弹性恢复力的计算式。.对层间隔震结构输入近断层地震动进行限位振动台模型试验。分析实验数据，给出了不同隔震层位置下，不同刚度、不同预留间隙和不同阻尼限位器的限位效果以及软限位对结构动力响应的影响规律。实验表明，隔震层设置限位装置可控制隔震层位移，同时将结构响应控制在规范允许范围内。为隔震层软限位技术应用于工程，提供了实验依据。.分析了近断层脉冲型地震作用下层间隔震结构隔震层软限位机理。当隔震支座的位移达到预留间隙时，软限位装置发挥作用，提供软限位刚度（或同时提供阻尼），限制隔震层水平位移的增大。在软限位接触时，会对上部结构产生脉冲激励，可能激发高阶阵型响应，引起上部结构动力响应有所增大。.提出了近断层地震动作用下层间隔震结构隔震层大变形软限位减震结构体系优化设计方法。限位装置设计参数包括：（1）预留间隙，取小震作用下隔震层位移作为下限；（2）限位刚度，取将隔震层位移限制在规范允许限值情况下的限位刚度作为最小需求限位刚度；（3）限位阻尼，适当增加限位阻尼，同时考虑施工方便，控制造价。参数设计时，首先选定初始值，然后建模计算，对限位参数进行优化，以取得结构动力响应满足规范要求的限位参数设计值。