钢筋混凝土梁裂纹扩展荷载的断裂力学研究

Analysis of RC Beams by Fracture Mechanics

本文将线弹性断裂力学用于钢筋混凝土材料。对12根跨中带裂纹的钢筋混凝土梁试件进行了试验研究。结果表明,裂纹扩展荷载对裂纹长度是敏感的。文中采用了一种新的接触单元模拟钢筋和混凝土之间的滑移。用8结点等参元按断裂力学计算的数值结果与试验值符合很好,而按强度准则σ_(max)≤σ_e所确定的裂纹扩展荷载则远低于试验值。由此可以说明,线弹性断裂力学在文中的条件下是适合于钢筋混凝土材料的。文中还分析了不同因素对裂纹扩展荷载的影响。

In this paper, the fracture mechanics of reinforced concrete is discussed. Tests are performed on reinforced concrete beams with crackstimulating notches. Different parameters and curves are obtained. It is shown that the load producing rapid crack propagation is sensitive to the notch. Singular element method is applied to analyze beams. A new kind of contact element is proposed to model the slip between steel bar and concrete. A usual eight-noded quadratic isoparametric element is applied to idealise both the concrete and the bar. The results predicted by fracture mechanics are shown to be reasonably good agreement with the experimental data. But those based on tensile strength criterion are far lower. Although further research is necessary, the indication is that the concept of linear clastic fracture mechanics is applicable to reinforced concrete. It is also shown that both the slip between two materials and the area of bar have great influence on crack development.