基于三维细观数值方法的钢筋混凝土悬臂梁抗剪行为研究

从细观角度出发，结合混凝土内部组成的微/细观结构特征，考虑钢筋与混凝土之间的非线性粘结-滑移行为，建立了钢筋混凝土悬臂梁力学行为研究的三维细观尺度数值分析模型与方法。基于建立的数值方法，对已有关于钢筋混凝土悬臂梁在循环往复荷载作用下的抗剪破坏试验进行模拟，模拟结果与试验结果的良好吻合表明了细观数值方法的可行性。进而在此基础上，拓展模拟了不同箍筋率下钢筋混凝土悬臂梁的剪切破坏过程，揭示了箍筋对悬臂梁滞回特性及抗剪承载力的影响规律。研究表明:1）细观数值分析模型能较好的模拟构件的宏观力学性能，且能细致的描述裂缝在混凝土中的发展过程；2）随着配箍率的增加，梁抗剪承载力及延性增加，但随着配箍率增加，钢筋混凝土梁抗剪承载力增加趋势减缓。建立的细观尺度数值方法可为有/无腹筋混凝土梁抗剪/抗弯破坏尺寸效应提供理论支持。

STUDY ON SHEAR PERFORMANCES OF REINFORCED CONCRETE CANTILEVER BEAM USING 3D MESO-SCALE SIMULATION METHOD

From the mesoscopic view, combining with the micro/mesoscopic structural character of concrete, as well as considering the nonlinear binding-slip behavior between a steel bar and concrete, a three dimensional meso-scale numerical model and the method for a reinforced concrete (RC) cantilever beam were set up. Based on the numerical method, the shear performance of a RC cantilever beam under cyclic loading was analyzed, the numerical results are well fitted with the experimental results, and it shows the feasibility of the mesoscopic numerical method. Then on this basis, the shear-failure process of different stirrup-ratio-RC cantilever beams is further simulated, and the influence regularity of stirrup on hysteretic characteristic and the shear bearing capacity of a cantilever beam are revealed. The research shows that:1) the mesoscopic numerical model can better simulate the mechanical properties, and it can detailed describe the development process of cracks in concrete; 2) with the increase of stirrup ratio, shear-bearing capacity and ductility increase, but with the increase of stirrup ratio, the increasing trend of RC-beam-shear-bearing capacity slow down gradually. The meso-scale numerical method can provide a theoretical support for the shear/bend size effect of beams with/without web reinforcement.