弯管结构塑性极限分析的数值方法及应用

从塑性极限分析数值计算的角度，分析了多组载荷联合作用下弯管结构的塑性极限承载能力。为了克服塑性极限上限分析中目标函数非线性非光滑所导致的数值困难，提出了一种弯管结构塑性极限上限分析的无搜索优化迭代算法；采用一种改进的弯管单元并利用加载路径的径向射求解方案处理多组载荷系统。通过对典型弯管结构进行塑性极限分析得出了一些有价值的结论。

A NUMERICAL METHOD FOR PLASTIC LIMIT ANALYSIS FOR PIPE STRUCTURES AND ITS APPLICATIONS

This paper analyzes the plastic limit loads of pipe structures under multi-loading systems from the point of view of the numerical limit analysis. To overcome the numerical difficulties caused by the non-linearity and non-smoothness of the objective function, a computational method is developed for the limit analysis of pipe structures. A direct iteration algorithm is proposed to solve the formulation of mathematical programming. During the process of iteration, rigid and plastic zones are continually distinguished and the objective function is modified. In view of the complexity of geometry and loading conditions of pipe structures, an improved pipe element is used, which need only little input data and amount of computation. Numerical examples show the present method has the advantages of fast convergence, good stability and high precision. Some valuable conclusions are drawn. The computational results can provide theoretical foundations for plastic analysis and design of pipe structures. The loading path scheme for multi-loading systems is used in the numerical limit analysis. Numerical examples illustrate the efficiency and applicability of the numerical method.