中文摘要：

基于三维固定裂缝模型基本理论,编制Fortran程序,对经典3点弯曲梁在集中力作用下的开裂问题进行数值模拟。固定裂缝模型基于断裂能守恒,通过调整混凝土应力-应变软化曲线来适应不同大小的网格模型。将计算所得的特征点的应力-应变曲线和假定的应力-应变曲线进行对比,结果表明不同网格模型的断裂能基本一致,编制的程序正确,固定裂缝模型在一定程度上能够克服网格敏感性问题。对同一网格模型选用不同断裂能参数进行模拟,比较在相同荷载条件下的荷载-位移曲线和应变包络图,结果比较符合实际情况和基本理论,表明固定裂缝模型能较好地模拟出裂缝的开展过程。

英文摘要：

The Fortran program, based on the three-dimensional fixed crack model, simulated the classic three-point bending beam under concentrated forces.Fixed crack model, based on the consistent fracture energy, adjusted the stress and strain softening curve to adapt to different size of grid models.Compared the calculated stress strain curve of keypoint and the assumed stress strain curve,the results showed that the fracture energies of different grid models were almost the same and the fortran program is right, so the fixed crack model can overcome the grid sensitivity to some extent.Choosed different fracture parameters to simulate the same grid model and compared the load displacement curves and strain envelope diagrams under the same load condition, the results conformed to the actual situation and the basic theory, So the fixed crack model theory can well simulate the crack development process.