基于扩展有限元法的混凝土梁断裂性能数值分析

摘要

It presents a numerical study on the fracture behavior of concrete beams by extended finite element method.Based on the measured fracture energy Gf with size effect and the bilinear model of local fracture energy,the real fracture energy GF of concrete is obtained by least squares fitting.The models of two kinds of fracture energy Gf and GF are compared and analyzed by extended finite element method,and then real fracture energy GF is used as the parameter of concrete to analyze the fracture behavior of three-point bending beams with different crack heights and different beam widths.The analysis results indicate that it is more accurate and effective to use real fracture energy as the concrete material parameters.When the initial crack height ratio increase,the fracture toughness of concrete beams increase first and then decrease gradually.The fracture toughness of concrete beams are independent on beam width.%用扩展有限元法对混凝土梁的断裂性能进行了数值研究.以试验所测具有尺寸效应的混凝土断裂能Gf作为基础数据,利用局部断裂能的双线性模型,通过最小二乘法拟合得到与尺寸无关的混凝土真实断裂能GF.在此基础上,基于扩展有限元法,首先对比分析了采用断裂能Gf,GF的模型,然后以真实断裂能GF作为混凝土的参数,对不同缝高比和不同梁宽的混凝土三点弯曲梁的断裂性能进行数值分析.分析结果表明:当利用扩展有限元法对混凝土断裂问题进行计算时,采用真实断裂能GF作为混凝土材料参数更准确有效;随着初始缝高比增大,混凝土梁断裂韧度先增大后逐渐减小;混凝土梁断裂韧度与梁宽无关.