三点弯曲下钢纤维高强混凝土的断裂性能

通过50个尺寸为100 mm×100 mm×515 mm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.

FRACTURE CHARACTERISTICS OF STEEL FIBER REINFORCED HIGH STRENGTH CONCRETE UNDER THREE-POINT BENDING

Through the three-point bending test on 50 specimens of steel fiber reinforced high strength concrete (SFHSC) with the size of 100 mm× 100 mm ×515 mm, the effect of the fiber volume fraction (pf) upon the effective crack length (al) fracture toughness (KIc) and critical crack opening displacement (δc) of high strength concrete (HSC) was studied. The results show that the increment ratio of the KIc of SFHSC increases linearly with the increase of pf. The critical crack tip opening displacement (δt) and the critical crack mouth opening displacement (δm) of SFHSC increase exponentially with the increase of pf. The al is basically close to a stable value. Based on the test results, the formulae were established for calculating al, KI c and δc (δt and δm).