EVALUATION OF LOADS AND STRUCTURAL RESISTANCES IN THE LIMIT STATE DESIGN

在极限状态设计的实用方面的发展中，有相当多的荷载和结构抗力问题需要解决。本文重点研究了钢结构构件的极限状态评估、地震和强风作用下的动力响应、荷载组合模型，并以长细比和宽厚比为主要参数，利用已有的试验结果，对钢结构构件的极限状态进行了局部屈曲和欧拉屈曲的评估，并以数据库的形式进行了整理。为了有效地利用极限状态设计，这种努力应该继续下去。机翼响应研究是通过建立摆动-扭转振动的分析模型来进行的。采用具有特定相关性的模拟机翼载荷波动进行数值响应分析。地震反应研究由两部分组成，一部分是对缩尺结构的记录反应进行分析，揭示钢结构的倒塌过程；另一部分是高层建筑结构性能的统计评估，以二次弯矩可靠度计算结构的抗震安全性。荷载组合模型是极限状态设计的重要组成部分。提出了时变负荷组合的水平交叉率方法，并用数值方法求出了负荷系数。通过对对数正态随机变量求和的处理，给出了一个简单的荷载组合实例。最后，讨论了极限状态设计的定义，以增加二次开发的合理性。总结了今后应注意的几个问题，重点是载荷概率模型的改进和目标可靠性的理论基础。

In the development of practical aspects of the limit state design, quite a few problems for the load and the structural resistance are to be solved. In this study, (1) the evaluation of limit state for members in steel structure, (2) the dynamic response for both the earthquake and the strong wind, (3) the load combination model are focused to be investigated.The limit state in terms of local buckling and Euler buckling is evaluated with aids of existing experimental results, which are also rearranged in a form of data base with slenderness ratio and width-thickness ratio as major parameters. Such efforts should be continued further for effective uses of the limit state design.Wing response studies are conducted by establishing an analytical model for the sway-torsional vibration. Simulated wing load fluctuations with a specified correlation are used for numerical response analyzes. Seismic response studies consist of two parts, one is the analysis of recorded responses of scaled structure to reveal the collapse process of steel structure and the other is the statistical evaluation of structural behavior for high rise buildings to compute the seismic safety in terms of the second moment reliability.The load combination model is one of important parts of the limit state design. Level crossing rate approaches are developed for combinations of time varying loads, then load factors are numerically obtained as a proposed model. The summation of log-normal random variables is treated to provide a simple load combination example.Finally the definition of limit state design is discussed to increase the rationality of further development. A few future problems are also summarized with an emphasis on the improvement of the probabilistic model of load and the theoretical basis for the target reliability.