远场长周期地震下基于规范设计隔震结构的抗震性能研究

Seismic Performance of Base-Isolated Structures Under Far-field Long-period Ground Motion Based on Seismic Codes

隔震结构具有较长自振周期,且容易受地震动长周期特性的影响,因此其在长周期地震动作用下的抗震性能值得研究。以某基于规范设计的基础隔震结构为例,通过对该结构在规范规定地震作用和远场长周期地震作用下的地震响应进行分析和对比,研究长周期地震动对结构地震响应的影响;通过对钢筋和混凝土的损伤状态进行定义和标识,探讨长周期地震作用下基础隔震结构的损伤分布规律。研究结果表明,长周期地震动作用下隔震结构发生破坏的概率远大于具有相同峰值地面加速度的普通地震动,其中长周期地震动反应谱的谱峰值"后移"被认为是造成这种情况的主要原因,且长周期地震动作用下隔震结构的损伤分布并不均匀,其主要集中在结构的底层。

A base-isolated structure is a civil engineering structure with a long natural vibration period and is easily influenced by the long period spectrum characteristics of seismic ground motion. Some re search results show that, compared with far-field ordinary seismic ground motion, an isolated structure may experience greater deformation under far-field long period ground motion, and that this will cause structural damage. Therefore, the seismic performance of isolated structures under long period ground motion is worth studying. In this paper, nine far field long period ground motion records were chosen from the Pacific Earthquake Engineering Research Center （PEER） as seismic input, and a lea＆rubber bearing （LRB） base isolated structure, based on the design code, was taken as the object of study. The seismic response of the structure was analyzed and compared under far-field ordinary and far field long period ground motion, and the effect of long period ground motion on isolated structures was studied. The damage distribution law for base-isolated structures under long period ground motion is discussed by defining the damage status of the concrete and steel in the structure. The research results show that the probability of damage to base-isolated structure under long period ground motion is far greater than un der ordinary ground motion. Furthermore, the damage distribution in isolated structures under long peri od ground motion is uneven and is mainly concentrated in the bottom floors of the structure.