多种材料结构体系塑性极限分析的弹性补偿有限元法

弹性补偿有限元法是一种简单、高效的结构塑性极限分析方法,目前仅用于采用单一材料的结构体系中。在经典弹性补偿有限元法中引入承载比概念,并据此对算法进行了改进,既保留了算法通过结构广义应力场不断平均化获得下限荷载的基本优化思想,又融入了平均化过程按各种材料的广义强度成比例调整的新思想,结构破坏时每种材料同时趋于各自的广义强度,使算法适用于对采用多种材料的结构体系做塑性极限分析。经典算例的对比分析表明,改进算法的分析结果是收敛的、准确的和稳定的。对复杂钢框架结构的极限荷载和破坏模式分析也表明,改进算法可用于采用多种材料的实际工程结构的安全评价中。

ELASTIC COMPENSATION FINITE ELEMENT METHOD FOR PLASTIC LIMIT ANALYSIS OF A STRUCTURE SYSTEM WITH MULTI-MATERIAL

The elastic compensation finite element method (ECFEM) is a simple and efficient method of plastic limit analysis, and it is only applicable to a commaterial structure system. An improved algorithm based on ECFEM is proposed by introducing bearing-ratio into the standard algorithm, which not only keeps the basic thought of flattening generalized stress in structure, but also leads the flattening process in proportion with generalized strength of every material. Using this method, all materials reach their generalized strength when the structure system is in its failure mode, and ECFEM can be expanded into the limit analysis of a structure system with multi-material. Contrastive analysis of some classical examples shows that the results using the algorithm are convergent, accurate and stabilizing. Furthermore, the algorithm is also verified to be feasible in safety evaluation of complicated structures by the results of limit load and failure mode.