钢筋混凝土无腹筋梁受剪承载力尺寸效应研究

利用有限元软件ＤＩＡＮＡ中基于断裂力学的有限元模型，对钢筋混凝土无腹筋梁进行了非线性 分析。在与试验结果进行对比分析的基础上，选取了其中一组试件，在更大尺寸下变换不同骨料粒径、 混凝土强度、截面纵筋配筋率、剪跨比进行建模。通过数值计算，分析了截面高度和骨料粒径对钢筋混 凝土无腹筋梁受剪承载力的影响，并且改进了我国混凝土规范无腹筋构件受剪承载力公式。结果表明: 最大骨料粒径的变化对无腹筋梁受剪承载力无明显影响；梁的破坏剪应力随截面高度增加而降低，但破 坏剪应力的降低幅度随梁高的增大而逐渐减小；改进后的无腹筋构件受剪承载力公式能较好反映大尺 寸无腹筋构件尺寸效应的影响。

Size Effect of Shear Capacity of Reinforced Concrete Beams Without Stirrups

The finite element software DIANA was used in a finite element model based on fracture mechanics, and the nonlinear finite element was adopted to analyze the reinforced concrete beams without stirrups. Based on the comparison analysis with test results, a group of specimens in larger size were selected for modeling in different aggregate size, con- crete strength, longitudinal reinforcement ratio and shear span. According to the numerical calculations, the influence of aggregate size and depth on the ultimate shear strength of reinforced concrete beams without stirrups was discussed, and the shear design method in the Code for Design of Concrete Structures （GB 50010 - 2010） for reinforced concrete mem- bers without stirrups was improved. The results indicate that the change of the maximum aggregate size has no significant impact on the failure shear stress of reinforced concrete beams without stirrups, and the failure shear stress is gradually reduced with the increase of depth, but the variation of the shear stress failure is decreased gradually with the increase of depth. The improved shear equation of the members without stirrups can well reflect the size effect for large members.