【摘要】 为了研究双缝混凝土三点弯曲梁的断裂性能,分别对初始缝高比为0.4的单缝,主缝缝高比为0.4、次缝缝高比为0.2～0.4及主次缝间距为120 mm和160 mm的双缝标准混凝土三点弯曲梁,共24个试件进行了试验研究。基于双K断裂理论,分析了次缝缝高比及主次缝间距对实测的荷载-裂缝张口位移P-δ曲线的影响。结果表明:随着次缝缝高比的增大,试件的起裂荷载从4.65 kN增至7.12 kN,增大53.1%,最大荷载从7.37 kN增至8.22 kN,增大11.5%;随着主次缝间距的增大,试件的起裂荷载、最大荷载及其比值均同步先增大后减小,且当主次缝间距为80 mm时,均达到最大。相比单缝试件,次缝缝高比越大,实测P-δ曲线线性段的斜率越高,主次缝间距越大,P-δ曲线线性段的斜率越小。更多还原

【Abstract】 To obtain the fracture properties of three-point bending concrete beam with double cracks, 24 specimens were tested in this paper. The initial crack-depth ratio of the specimens with a single crack is 0.4. For the specimens with double cracks, the initial crack-depth ratio of the main crack(MC) is 0.4 and it is 0.2～0.4 for the secondary crack(SC), while the distances between the SC and MC are 120 mm and 160 mm, respectively. Based on the double-K fracture theory, the effect of the crack-depth ratio of SC and the distance between SC and MC on the initial load, the maximum load, and the P-δ curve were studied. The results indicate that, with the increase of the crack-depth ratio of the SC from 0 to 0.4, the initial load of the specimens increased from 4.65 kN to 7.12 kN by 53.1%, and the maximum load increased from 7.37 kN to 8.22 kN by 11.5%. With the increase of the distance between SC and MC, the initiation load, the maximum load and the ratio of initial load to maximum load increased at first and then decreased. Meanwhile, values of them reached to the peaks when the distance was 80 mm. Compared to single crack specimens, the bigger the ratio of the SC, the larger the slope of the linear segment of measured P-δ curve; the larger the distance between SC and MC, the smaller the slope of linear segment.更多还原