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通过50个尺寸为100mm×100mm×515mm的钢纤维高强混凝土切口梁三点弯曲试验,研究钢纤维体积率对高强混凝土有效裂缝长度、断裂韧度和临界裂缝张开位移的影响。结果表明:随着钢纤维体积率的增加,钢纤维高强混凝土断裂韧度增益比基本呈线性增加,临界裂缝尖端和临界裂缝嘴张开位移分别呈指数型增加。有效裂缝长度趋于稳定值,基本不受钢纤维体积率变化的影响。在分析试验结果的基础上,建立了钢纤维高强混凝土有效裂缝长度、断裂韧度和临界裂缝张开位移的计算公式。
The effect of steel fiber volume fraction on the effective crack length, fracture toughness and critical crack opening displacement of high strength concrete was studied by three-point bending test of 50 steel fiber reinforced high strength concrete beams with dimensions of 100mm × 100mm × 515mm. The results show that with the increase of the volume fraction of steel fiber, the fracture toughness gain ratio of steel fiber reinforced concrete increases linearly, and the critical crack tip and critical crack mouth opening displacement increase exponentially. The effective crack length tends to be stable, basically not affected by the change of volume fraction of steel fiber. Based on the analysis of experimental results, the formulas for calculating the effective crack length, fracture toughness and critical crack opening displacement of steel fiber reinforced high strength concrete are established.