中文摘要：

建立钢桁梁结构体系可靠性优化的数学模型,在常规优化模型的基础上,以纵梁和横梁的弯曲失效、腹杆拉应力和屈曲失效为主要失效模式,采用β约界法构建出相关性较低的构件并组建成失效树。提出适用于钢桁梁结构的体系可靠性优化方法,该方法采用神经网络方法求解具有隐式功能函数复杂结构的体系可靠度,然后将体系可靠度通过罚函数的方式引入到个体适应度计算中,通过遗传算法实现体系可靠性优化。采用2种优化方案对某悬索桥钢桁梁结构进行体系可靠性优化分析。研究结果表明：该结构最初失效状态主要表现为腹杆的压应力屈曲失效,最终失效状态表现为纵梁和横梁跨中弯曲失效;2种方案的优化结果都表现为纵、横梁截面面积的减小和腹杆截面面积的增加,这表明该结构的纵梁和横梁的抗弯刚度较大,而腹杆屈曲强度储备稍不足。

英文摘要：

The system reliability models of steel truss beam structure were established. Bending failure modes of beam and carling were selected to be the main failure mode. The β unzipping method was used to establish the failure tree composed by components with lower correlation based on the convention optimization model. The structural optimization design method was presented based on system reliability. Neural network was used to analyze the system reliability with implicit function, and then system reliability was introduced into the genetic algorithm in the form of penalty function. Two optimization analysis schemes were put forward to analyze the system reliability optimal results of a steel truss beam structure. The results show that the initial structural failure mode is bucking failure of web member and the final structural failure mode is bending failure mode of beam and carling; the results of the two schemes are the decrease of the beam cross section area and the increase of the area of the web member, the beam flexural rigidity of the beam is enough, but the bucking strength is insufficient.