考虑长周期地震动作用特性的RC框架柱抗震性能及失效机理研究

The displacement time-history responses of high-rise building structures under long-period ground motions have the significant large-displacement and long-duration characteristics. Revealing the influence mechanism of this type of action characteristic on seismic performance and failure mechanism of the structural component is the key to investigate the influence of long-period ground motion on the high-rise building structure. This project proposes the thought that reflecting the large-displacement and long-duration action characteristic of the long-period ground motion by the loading protocol of pseudo-static test. As the conventional pseudo-static loading protocol cannot reflect this action characteristic, this project firstly analyzes the distribution laws of displacement amplitudes and number of cycles corresponding to the elastic-plastic SDOF system under long-period ground motions, and on this basis establishes the pseudo-static loading protocol which can reflect the action characteristics of long-period ground motions. Then, through the pseudo-static test, numerical modeling and theoretical analysis, the strength and stiffness degradation laws, energy dissipation performance, ductility property and the influence factors of RC frame columns under long-period ground motions are investigated. The hysteretic model and damage model of the RC frame column which can consider the influence of action characteristic of the long-period ground motion are established. The damage and failure mechanism of RC frame column under long-period ground motion is revealed. The research results can provide the foundation to reveal the influence mechanism of long-period ground motion on the high-rise building structure. It has the important theoretical value and engineering significance.

长周期地震动作用下高层建筑结构的位移响应时程具有明显的大位移与长持时特征，揭示该作用特性对结构构件抗震性能及损伤失效的影响机理是研究长周期地震动对高层建筑结构影响的关键。本项目提出将长周期地震动对结构的大位移与长持时作用特性反映到拟静力试验加载制度的思想，首先针对传统拟静力试验加载制度无法反映该作用特性的问题，基于雨流计数法分析长周期地震动作用下弹塑性SDOF体系位移响应幅值与循环数分布规律，在此基础上构建可反映长周期地震动作用特性的拟静力试验加载制度；然后通过拟静力试验、数值模拟与理论分析，研究长周期地震动作用下RC框架柱的强度与刚度退化规律、耗能性能、延性性能及其影响因素，建立考虑长周期地震动作用特性影响的RC框架柱恢复力模型与地震损伤模型，揭示长周期地震动作用下RC框架柱的损伤失效机理。研究成果可为揭示长周期地震动对高层建筑结构的影响机理提供基础，具有重要的理论价值与工程意义。

长周期地震动因含有丰富的低频成分而易使自振周期较长的（超）高层建筑发生震害，现有研究多集中于长周期地震动作用下整体结构的响应分析，而对长周期地震动的影响机理尚缺少深入系统的研究。本项目针对长周期地震动作用下高层结构位移响应时程的大位移与长持时特征，提出将长周期地震动的作用特性反映到拟静力试验加载制度，进而通过拟静力试验研究长周期地震动对结构构件抗震性能影响机理的研究思路。首先，建立了可反映长周期地震动作用特性的拟静力试验加载制度，并编制了软件，可快速得到适用于多种类型构件的拟静力试验加载制度；然后，以RC柱为研究对象，通过拟静力试验与有限元模拟分析，研究了长周期地震动作用特性对RC柱抗震性能的影响机理。此外，系统分析了长周期地震动的频谱特性与强度指标，以及高层RC框架结构在长周期地震动作用下的响应特征、损伤失效模式以及倒塌破坏机制。