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Clarification of Unstable Behavior of Building Steel Frames Subjected to Repeated Loading and Development of Estimation Method of Safety

阐明建筑钢框架在重复荷载作用下的不稳定行为并开发安全评估方法

基本信息

批准号：
04650518
负责人：
UETANI Koji
金额：
$ 1.28万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

A series of theoretical and numerical studies have been carried out to clarify the unstable behavior of framed structure, which can not be captured with any simplified method of numerical analysis used in design practices, and to develop an estimation method of safety. The results obtained by these studies are summarized as follows :1. A new type of critical behavior in a H-shaped simple unit frame has been found and its appearance condition has been clarified by performing a symmetry limit analysis.2. A new type of critical behavior of multi-story multi-span planar frames, which is characterized by cyclic growth of a bow-shaped column deflection mode spanning a certain number of stories. This critical behavior is possible to occur, if the column force is in excess of a definite limit, which can be predicted by the symmetry limit theory. The mechanisms of the appearance and cyclic exponential growth of the column deflection mode have also been clarified theoretically.3. Dynamic response analyzes have been performed on some multi-story frames subjected to harmonic ground motions and recorded seismic ground motions. It has been shown that a similar type of column deflection mode to that observed in the static behavior can appear also in the dynamic response to the repeated ground motions.4. Both the appearance limit condition and the deflection mode of this critical behavior in the responses to the dynamic ground motions well coincides with those of the critical behavior under statically repeated loadings.5. Since the limit condition is to be determined by the parameters of the frame itself only, then it should be useful for the estimation of seismic stability and practical seismic design of framed structures.

本文开展了一系列的理论和数值研究，以澄清框架结构的不稳定行为，这些行为无法用任何简化的数值分析方法在设计实践中捕捉到，并开发了一种安全估计方法。研究结果总结如下：1。在h形简单单元框架中发现了一种新的临界行为，并通过对称极限分析阐明了其出现条件。多层多跨平面刚架的一种新型临界行为，其特征是跨一定层数的弓形柱挠度模式循环增长。如果柱力超过一定的极限，这种临界行为是可能发生的，这可以通过对称极限理论来预测。从理论上阐明了柱挠曲模态的出现和循环指数增长的机理。对若干多层框架结构在谐波地震动和记录地震动作用下的动力响应进行了分析。研究表明，在反复地震动作用下的动力响应中，柱的挠度模式与静力行为中观察到的相似。该临界行为在动力地震动响应中的表现极限条件和挠度模式与静力重复荷载作用下的临界行为吻合较好。由于极限条件仅由框架本身的参数决定，因此对于框架结构的抗震稳定性估计和实际抗震设计应是有用的。