不同配筋率对钢筋混凝土三点弯曲梁断裂韧度的影响

Effects of Various Reinforcement Ratio on Fracture Toughness of Reinforced Concrete for Three-points Bending Beams

为深入了解配筋率对钢筋混凝土断裂韧度的影响,制作了3组12根带预制裂缝的钢筋混凝土三点弯曲梁并做了断裂试验,根据试验导出了钢筋混凝土三点弯曲梁试件断裂参数解析计算公式,分析了不同配筋率对钢筋混凝土三点弯曲梁断裂韧度的影响程度。结果表明,钢筋混凝土三点弯曲梁试件的开裂荷载主要由混凝土主体结构所决定,最大荷载主要由混凝土内部配置的钢筋情况所决定;裂缝亚临界扩展相对值随着配筋率的增加呈线性增加;配筋率的变化对失稳断裂韧度有一定影响,但对起裂断裂韧度影响不大;配筋率的增加,可有效提高试件的韧性和抵抗失稳破坏的能力。

To understand deeply the influence of reinforcement ratio on fracture toughness of reinforced concrete, the fracture test was designed for 3 groups include 1Z reinforced concrete specimens with different reinforcement ratios. The analytic computational formula for the fracture parameters of reinforced concrete three-point bending beams was derived based on the fracture theory of concrete. And the influence rules of reinforcement ratio on fracture toughness were stud- ied. The results show that the cracking load of reinforced concrete three-points bending beams depends on the concrete structure, and the maximum load depends on the steel bars inside the concrete; the relative values of subcritical crack propagation length appears a linearly increasing trend with the increased of reinforcement ratios; the initial fracture tough- ness is not affected by the reinforcement ratios, but the unstable toughness has little impacts by reinforcement ratios~ the ductility and the fracture resistance can be improved effectively when the reinforcement ratios are increased.