A STUDY ON THE DEVELOPMENT OF STABILITY DESIGN METHODS FOR STEEL FRAMES

本研究的目的是发展一种钢框架稳定性的设计方法。首先，对钢框架结构的稳定性设计方法进行了严格的回顾。其次，提出了一种新的框架稳定设计方法。与有效屈曲长度的概念不同，该方法是基于弹性二阶分析。在该方法中，引入与缺陷相对应的等效初挠度是至关重要的。为此，提出了一个新的利用曲率的等效挠度公式。此外，提出了一种方法来解释这个公式的系统应用到框架与阶梯形截面。算例表明了该方法的有效性。最后，给出了考虑构件局部屈曲的钢框架强度的二阶简化分析。在分析中，引入了短柱的初始等效挠度和局部屈曲准则。另一方面，虽然已经进行了一些详细的分析，以明确的互动行为，有很少的协议彼此。因此，这些结果的详细比较表明，使用力矩-推力-曲率关系的分析是最好的协议与Q因子的方法，其准确性由实验证实。因此，通过与使用力矩-推力-曲率关系的分析进行比较，检验了所提出的简化分析的有效性。

The purpose of this study is to develop a design method for stability of steel frames. At the beginning, a critical review of stability design methods for steel frames is performed. Next, a new stability design method for frames is presented. Contray to the effective buckling length concept, the proposed method is based on the elastic second-order analysis. In this method, the introduction of equivalent initial deflections corresponding to the imperfections is of utmost importance. Therefore, a new equivalent deflection formula using curvature is suggested. Moreover, a methodology is proposed to explain the systematic application of this formula to a frame with stepped cross section. The validity of the method is demonstrated by some examples. Finally, a simplified analysis of steel frame strength by the second-order analysis, consideringthe local buckling of component plates, is shown. In the analysis, the initial equivalent deflection and local buckling criterion of stub column are introduced. On the other hand, although several elaborate analyzes have been performed to make clear the interactive behavior, there is little agreement with each other. Therefore, a detailed comparison of those results has shown that the analysis using moment-thrust-curvature relations are in best agreement with Q-factor method, accuracy of which was confirmed by experiments. Accordingly, the validity of the proposed simplified analysis was examined by comparison with the analysis using moment-thrust-curvature relations.