钢筋混凝土框架结构连续落层倒塌的混沌特征

摘要

In Wenchuan earthquake, general fail feature of RC frame structure is column-plastic-hinge weak layer yield mode, that contradict yield behavior of ' Strong Column and Weak Beam' recommended in Chinese seismic code. Through analyzing these two yield modes based on chaotic theory, definite chaotic features of RC frame structure are detected in progressive storey collapse caused by weak layer yield. Specifically, features are sensitive dependence on initial status and appearance of nonperiodic motion ( simple attractors are beam lastic-hinges and column plastic-hinges, strange attrsctor is yield of weak layer). Chaotic theory is introduced into research on earthquake disasters of buildings for the first time, suggestion in this paper is adding substructure to avoid appearance of post-yield negative stiffness and chaos.%汶川地震中钢筋混凝土框架结构破坏的主要特征为柱铰式薄弱层屈服破坏,而抗震规范所倡导的“强柱弱梁”机制未能实现.本文基于混沌理论的观点,通过分析框架结构的两种屈服模式,首次在薄弱层屈服引起连续落层倒塌的破坏过程中发现了明显的混沌特征,即具有对初始状态的敏感依赖性以及非周期运动的出现.本文引入混沌理论研究建筑震害,假定混沌运动的简单吸引子是梁、柱的塑性铰,奇怪吸引子是结构的薄弱层屈服.通过研究,提出了在主结构中增设次结构可避免出现屈服后负刚度和混沌现象的设计建议.