（华东建筑设计研究院有限公司， 上海 200041）

［摘要］针对超高层结构在罕遇地震弹塑性分析中发现的位移响应振动周期相对于弹性结果出现“缩短”的现象，从概念和理论角度进行原因分析。结果表明，结构位移响应由稳态振动和瞬态振动叠加而成的基本特征是发生周期“缩短”的必要前提条件，地震波频谱特征与结构自由振动周期的相互关系以及结构阻尼的衰减效应共同导致了位移响应周期的变化。明确了易于发生周期“缩短”的一般条件。通过理想弹性算例对分析结论进行验证。对发生周期“缩短”的案例补充震后模态分析，论证刚度退化的程度。最终形成对结构总体刚度退化进行评估的合理化建议。

［关键词］罕遇地震； 位移响应； 刚度退化； 周期缩短； 稳态振动； 瞬态振动

中图分类号：TU318， TU973文献标识码：A文章编号：1002-848X(2020)18-0091-05

Cause analysis of “shortening” of displacement response period for super high-rise structure under rare earthquake

AN Dongya

(East China Architectural Design & Research Institute Co., Ltd., Shanghai 200041, China)

Abstract:Aiming at the phenomenon that the vibration period of displacement response of super high-rise structure is “shortened” in the elasto-plastic analysis compared with the elastic result under rare earthquake, the reason analysis was carried out from the concept and theoretical point of view. The result shows that the basic feature of the displacement response of the structure, which is the superposition of steady-state vibration and transient vibration, is the necessary prerequisite for the occurrence of “shortening” phenomenon，and the relationship between the spectrum characteristics of seismic wave and the period of free vibration of structure，as well as the damping effect of the structure together lead to the change of the displacement response period. The general conditions for "shortening" of vibration period were clarified. The analysis conclusions were  verified by some ideal elasticity analysis cases. The post-earthquake modal analysis was supplemented for the case of displacement period "shortening" to demonstrate the degree of  stiffness degradation. Finally, reasonable suggestions for the evaluation of the overall stiffness degradation of the structure were formed.

Keywords:rare earthquake; displacement response; stiffness degradation; shortening of vibration period; steady-state vibration; transient vibration

*“上海超高层建筑设计工程技术研究中心”建设项目（14D22252800）。

作者简介：安东亚，博士，高级工程师，Email:dongya_an@arcplus.com.cn。