基于动力测试的竖向不规则大跨度空间钢结构抗震性能研究

RESEARCH ON SEISMIC BEHAVIOR OF VERTICALLY IRREGULAR LONG-SPAN SPACE STEEL STRUCTURE BASED ON DYNAMIC CHARACTERISTIC TEST

对复杂结构在环境激励下的现场实测及随机振动分析,所获得的频率等模态信息对于结构的动力性能评估和抗震设计有着重要意义。对一大跨度空间钢结构进行脉动观测,采用Nakamura法估算结构自振频率,基于有限元平台建立模型进行模态分析,与振动实测对比误差在2%以内,且振型相似。在此基础上进行静力弹塑性及动力弹塑性分析,结果表明:2~4层侧向刚度不规则成为结构薄弱部位;在推覆过程中受压支撑首先进入屈服状态,然后受拉支撑及梁端出现塑性铰,为结构提供了足够的耗能能力,结构没有出现整体倒塌;基于增量动力分析得到结构不同地震动强度作用下的响应,可供同类结构的动力特性和抗震性能的研究借鉴。

The field test and random vibration analysis of complex structures under environmental excitation were conducted,the obtained frequency and other modal information are of great significance to the dynamic behavior evaluation and seismic design of structures. The pulsating observation for a long-span space steel structure was carried out,and the natural frequencies of structures were estimated precisely by adopting the Nakamura. Based on the finite element software,the model was established and the modal analysis was carried out,and the fundamental frequency deviation was controlled within 2%,and the modes of vibration were similar. On this basis,the static elastic-plastic and dynamic elastic-plastic analysis were performed. The result showed that the lateral stiffness from layer 2 to layer 4 was irregular and became the weak part; the compression brace entered the yielding state first during the nappe process,and then the plastic hinges appeared in tension bracing and beam-end. These provided sufficient energy dissipation for the structure to avoid overall collapse. Based on the incremental dynamic analysis,the responses of structures under different earthquake intensities were obtained,which could provide reference for the study of dynamic characteristics and seismic behavior of similar structures.