Development of Optimization Method for Redundant Structure Based on Reliability Assessment Considering Damage of Collapse Mode

根据定义结构失效的标准，结构设计的基本原理可以分为两种。一种是基于单个构件初始破坏的许用应力设计。另一种是基于结构极限强度的设计。结构安全性的设计或评估可进一步分为确定性方法和概率方法。然而，尽管有这些差异，设计的总体目标是在保持足够的可靠性的情况下对结构进行优化。在本研究中，研究了基于初始失效和最终失效准则的强度的确定性和概率估计的桁架结构的优化设计。提出了一种新的基于极限强度的概率优化方法。它采用了对每种失效模式的安全系数进行优化分配的思想。通过与确定性方法的比较，讨论了基于可靠性的优化设计的意义。针对大型结构，提出了一种基于蒙特卡罗模拟和学习算法的递阶优化方法。

The fundamental philosophy of structural design can be divided into two according to the criterion which defines the failure of a structure. One is the allowable stress design based on the initial failure of individual member. The other is the design based on the ultimate strength of a structure. The design or the assessment of the safety of the structure can be further divided into deterministic and probabilistic approaches. However, regardless of these differences, the general goal of the design is an optimization of the structure with maintaining sufficient reliability.In this research, optimum designs of truss structures based on the deterministic and the probabilistic estimation of the strength for both the initial failure and the ultimate failure criteria are studied. Especially, a new probabilistic optimization method based on the ultimate strength is proposed. It employs the idea of optimum distribution of safety indices for each failure mode. Further, the significance of the optimum design based on the reliability is discussed through the comparison with deterministic approaches. Also, to deal with large scale structures, a hierarchical optimization method using MonteCarlo simulation with learning algorithm is proposed.