大跨拱支预应力网壳结构的模糊优化设计研究

针对武汉长江防洪模型展示大厅采用的大跨拱支预应力网壳结构,考虑优化目标函数与约束条件的模糊性,建立了该类结构体系的模糊优化设计数学模型;求解时首先通过约束水平截集法,将模糊优化模型转化为一系列确定性优化模型;然后基于拱支预应力网壳的结构特点,将预应力构件(拉索和吊杆)截面尺寸、预应力作用取值(构件初始应变)以及非预应力构件截面尺寸等优化设计变量分别归为不同的优化级别,采用分级优化思想对确定性优化模型进行求解;最后依据结构经济性与安全性平衡的目标求出结构的最优约束水平,从而得到最优的结构设计方案,并同时确定结构的合理预应力分布,由此形成了拱支预应力网壳结构的两阶段三级模糊优化设计方法。

STUDY ON FUZZY OPTIMIZATION DESIGN FOR LARGE-SPAN ARCH-SUSPENDED PRESTRESSED RETICULATED SHELLS

Taking the Wuhan Yangtse-river model testing hall as an engineering example,a fuzzy optimization model is established for the large-span arch-supported prestressed lattice shell structure considering the fuzzy characteristics of object function and restriction conditions.The restriction level cut method is first adopted to transfer the fuzzy model to a series of determined optimization model.Then based on the structural characteristics,design variables are divided into different optimization levels,including the section dimension of prestressed members(cables and hangers),prestress effect value(member initial strain) and the section dimension of non-prestressed members,and the multi-level optimization scheme is adopted to solve the model.Finally,the optimum restriction level is determined according to the criteria of balancing the economy and safety of the structure,and the optimum design scheme and reasonable prestress distribution are also obtained.In this way,the two-phase and three-level fuzzy optimum design method for this kind of structure is established.