含裂隙无腹筋梁的抗剪承载能力

分析混凝土梁内部既有裂隙的位置及角度对无腹筋梁抗剪承载力的影响, 制作多组含既有裂隙的试验梁, 进行梁的三点弯曲试验, 研究位于梁跨中和梁侧基本拱体范围内既有裂隙对无腹筋梁抗剪承载力的影响及裂缝扩展规律。结果表明: 梁上的既有裂隙对梁的抗剪承载力有削弱作用; 在其他条件相同的情况下, 梁跨中既有裂隙的裂尖距离梁底中部越近, 对无腹筋梁抗剪承载力的削弱作用越大; 梁侧既有裂隙的角度与基本拱体重合度越高, 对无腹筋梁抗剪承载力的削弱作用越大；梁侧既有裂隙的角度与基本拱体重合度越高, 梁底裂缝越容易扩展通过既有裂隙的两个裂尖, 反之, 梁底裂缝可扩展至既有裂隙中部。

Shear capacity of beams with cracks and without web reinforcement

In order to investigate the effect of the position and angle of the pre-existing cracks on the shear capacity of beams without web reinforcement, a number of experiment beams with pre-existing cracks were fabricated, the three-point bending experiment of the beam was carried out. The influence of pre-existing cracks located in the basic arch of the beam span and the beam side on the shear capacity of beams without web reinforcement and the law of crack propagation were studied. The results showed that the pre-existing cracks on the beam had a weakening effect on the shear capacity of the beam, which made the beam more prone to diagonal tensile failure. Under the same conditions, when the crack tip of the pre-existing crack in the beam span was closer to the middle point of the bottom of the beam, the greater the weakening effect on the shear bearing capacity of the beam without web reinforcement. When the coincidence degree of the angle of the pre-existing cracks on the beam side and the basic arch was higher, the greater the weakening effect on the shear bearing capacity of the beam without web reinforcement, and the cracks at the bottom of the beam propagate through the two crack tips of the pre-existing cracks was easier. Conversely, the cracks at the bottom of the beam could extend to the middle of the pre-existing cracks.