Fundamental Study on Failure Probability and Design Values of Load and Resistance of Steel Structures

1. 2.研究结果表明：（1）基于可靠性理论的设计方法不适用于失效概率较小的结构。(2)重要的是，在计算其失效概率之前，还应研究结构的极限强度和各种极限状态直至极限状态。(3)结构倒塌主要是由未知行为、极端预期或意外的危险以及人为错误引起的。(4)有必要建立一种方法来定量评估未知行为、极端预期或意外危险以及人为错误对失效概率的影响。(5)与初始缺陷和残余应力的变化相比，屈服应力的变化对极限强度的影响更为显著。(6)对于屈服极限状态，残余应力的变化不可忽略。(7)提出了一种基于强度极限的既有结构安全性评价的极限状态设计方法。

1.Fundamental theories have been developed to some extent in three papers.2.The following research results have been obtained :(1) Design methods based on reliability theory are not proper in structures with less failure probability.(2) It is important that the ultimate strength and various limit states up to the ultimate limit states of structures are also investigated prior to the calculation of their failure probability.(3) Collapses of structures are mainly caused by unknown behaviors, extremely expected or unexpected hazards, and human errors.(4) It is necessary to develop a method to evaluate quantitatively the influence of the unknown behaviors, extremely expected or unexpected hazards, and human errors upon the failure probability.(5) The influence of the variation of yield stress on the ultimate strength is predominant compared with the variation of initial imperfection and residual stress.(6) As for yield limit state, the variation of residual stress can not be neglected.(7) A limit states design method for evaluating safety on the strength limit of existing structures has been proposed.