空间结构弹塑性地震反应分析的简化模型与方法

Simplified model and procedure for elasto-plastic seismic response analysis of spatial structure

为解决应用模态推覆法计算空间结构弹塑性地震反应时,主振型数量过多、等效单自由度(ESDOF)体系双折线型力-位移关系与实际状况不吻合、结构荷载-节点位移-支座反力对应关系难确定等问题,提出一种简化的静力推覆方法.首先用SRSS方法组合振型节点位移以确定荷载模式,对结构实施静力弹塑性分析;然后采用整体刚度参数及等效质量,建立新的空间结构ESDOF体系;最后用多折线代替双折线表征该体系力-位移关系,基于该体系计算空间结构弹塑性地震反应.对K8单层球面网壳的分析表明:提出的计算模型及方法操作性强、省时;相对于时程分析结果,本方法所求大部分节点位移偏差在35%以内,进入塑性杆件数量偏差仅为7%,分布位置与时程分析结果基本对应.

In order to overcome the drawbacks existing in the modal pushover procedure for the elas- to-plastic seismic response analysis of spatial structures, including the excess of the dominant modes, the inaccuracy of the bilinear force-displacement relationship of the equivalent single degree of free- dom（ESDOF） system, and the indeterminacy of the relationship among structural load, nodal dis- placement and bearing force of the supports, a simplified static pushover analysis method is pro- posed. Firstly, the SRSS（ square root of sum of squares） rule is adopted to generate the load pattern for the static elasto-plastic analysis process; secondly, a modified elasto-plastic ESDOF system is es- tablished upon the overall structural stiffness parameter and the equivalent mass; in addition, a multi- linear force-displacement relationship is applied instead of the bilinear one to represent the mechani- cal property of the ESDOF system, which is then used for analyzing the elasto-plastic seismic re- sponse of spatial structures. A numerical example, which is carried out on a K8 single layer latticed shell, shows that the simplified model and the analysis procedure can exhibit satisfying operability and efficiency. Compared with the results given by time history analysis （THA）, most nodal dis- placements are predicted by this proposed approach with an error less than 35%, the quantity of members which enter inelastic phase is predicted with an error of about 7%, and the locations of these members are basically in accordance with those given by THA.