尺寸效应对钢筋混凝土梁裂缝的影响

运用断裂力学分析方法并采用断裂韧度判据研究尺寸效应对钢筋混凝土梁裂缝的影响。首先将三点弯曲梁自重、荷载、钢筋以及断裂过程区的粘聚力在裂缝尖端产生的应力强度因子叠加，检验其是否超过断裂韧度，以判断裂缝是否扩展。然后通过增大荷载以及增加裂缝长度的方式迭代计算，求得相应尺寸构件的承载能力，整个计算过程采用Matlab编程来实现。研究结果表明，尽管钢筋对混凝土梁的裂缝扩展起到限制作用，使其呈现出“塑性”特征，但是钢筋混凝土梁仍然存在尺寸效应现象，只是与素混凝土相比不明显。

Influence of Size ：,Effect on Reinforced Concrete Beam Crack

The influence of size effect on reinforced concrete beam crack was studied by fracture toughness. First, superimposing the stress intensity factors of the weight, load, steel bar of three - point bending beam and thecohesive strength of the fracture process zone on the crack tip and examine if it surpasses the fracture toughness so as to judge whether the crack will expand. SeCond, the carrying capacity of corresponding size component with increasing load and crack length was obtained with iterative computation. The result shows that, although the steel bar may limit crack expansion of Concrete beams and make them to display a plastic characteristic, size effect willstill appear in reinforced concrete beams, merely it is not obviouS Comparing with plain concrete beams.