中文摘要：

将有限变形单元与虚拟连接单元相结合，用于模拟准脆性材料破坏过程．首先基于精确的有限变形理论，采用第二类Piola-Kirchhoff应力与Green-Lagrange应变作为能量共轭的应力、应变对，推导出虚拟连接单元的单元刚度矩阵；通过数值算例，验证该单元的正确性与合理性，给出虚拟连接单元高度的取值范围，并与无此单元时的数值结果对比，给出误差分析；最后对典型的混凝土梁三点弯曲问题进行了数值模拟，其裂纹的产生、扩展与文献结果一致，论文为结构破坏过程的数值模拟提供了新方法和新思路．

英文摘要：

The combination of finite deformation element and virtual joint element is introduced to simulate the failure process of quasi-brittle materials. Based on accurate finite deformation theory,with the second Piola-Kirchhoff stress and Green-Lagrange strain as the energy conjugate stress and strain, the stiffness matrix of virtual joint element is derived. A numerical example is given to verify this virtual joint element, and some recommendations are offered for the range of height of the element. This method is further used to simulate crack propagating in a typical concrete three-point beam,and consistent results with other studies are predicted. This indicates the present method provides a new approach for the numerical simulation of failure process of quasi-brittle materials.