1．引言钢筋混凝土结构在荷载作用下，由于材料应力应变关系的非线性和混凝土开裂等原因，表现出很强的非线性性能。利用非线性有限元法对结构从受力到破坏的全过程进行模拟分析，是研究结构行为的有力工具。70年代以来，国内外许多学者对此做了大量的工作，取得了一定成果。研 1. Introduction Reinforced concrete structures exhibit strong nonlinear properties due to the nonlinear stress-strain relationship and cracking of concrete under load. Using the nonlinear finite element method to simulate and analyze the whole process of structure from stress to failure is a powerful tool for studying structural behavior. Since the 1970s, many scholars at home and abroad have done a lot of work and achieved certain results. research