普通混凝土剪切力学性能尺寸效应试验研究

Experimental study on size effect of shear mechanical properties of ordinary concrete

为探究普通混凝土剪切力学性能尺寸效应,设计3种不同剪切截面尺寸混凝土试件,应用剪切试验机对混凝土进行剪切试验研究,得到不同加载工况试件破坏形态和剪切荷载-位移曲线,通过剪切荷载-位移曲线提取剪切破坏荷载和剪切破坏位移(剪切破坏荷载对应的位移值),研究混凝土剪切力学性能尺寸效应,同时引用文献尺寸效应对普通混凝土受压和受拉力学性能影响试验数据对比分析,主要得到以下结论:随着剪切截面尺寸增大,平行和垂直于剪切方向混凝土平面微裂缝逐步减少,剪切断面混凝土碎渣逐步增多;混凝土剪切荷载-位移曲线发展趋势与单轴劈拉加载方式基本类似,曲线不受尺寸效应影响;混凝土剪切强度随着剪切截面尺寸提高而逐步降低,剪切峰值应变值(剪切破坏位移对应应变值)变化较小。同时从尺寸效应律角度定量分析尺寸效应对混凝土剪切强度影响;与混凝土单轴受压和单轴受拉尺寸效应数据对比,剪切受力方式受尺寸效应影响更为明显。

In order to explore the size effect of shear mechanical properties of ordinary concrete,three kinds of concrete specimens with different shear cross-section sizes were designed.The shear test machine was used to carry out shear tests on concrete.The failure modes and shear load-displacement curves of specimens under different loading conditions were obtained.The shear failure load and shear failure displacement were extracted by shear load-displacement curve(corresponding to shear failure load).The results show that with the increase of the size of the shear section,the plane micro-cracks parallel to and perpendicular to the shear direction decrease gradually,and the concrete slag in the shear section increases gradually.The development trend of shear load-displacement curve is similar to that of uniaxial splitting tension,and the curve is not affected by size effect.The shear strength of concrete decreases gradually with the increase of the size of shear section,while the peak shear strain(shear failure displacement corresponding to strain)changes slightly.At the same time,the effect of size effect on concrete shear strength is quantitatively analyzed from the angle of size effect law.Compared with the data of size effect under uniaxial compression and uniaxial tension,the effect of size effect on shear mode is more obvious.