中文摘要：

为研究弯矩作用下混凝土构件的裂缝形状及发展规律,制作了48组混凝土构件组,对构件跨中部位裂缝的发展规律进行试验研究.构件制作时分别考虑了预埋钢筋的数量、钢筋表面形状以及钢筋保护层厚度这三种因素.研究结果表明,在弯矩作用下,混凝土构件裂缝的横断面形状近似为楔形.同时,根据构件两侧表面的裂缝形状和深度,可以近似地推断出结构内部裂缝的形状和深度,从而可对构件内部裂缝对耐久性和受力性能的影响进行研究.对混凝土的开裂控制螺纹钢要好于圆钢,对裂缝的控制效果双根钢筋要好于单根钢筋,因此在一定范围内,钢筋布置较密比钢筋布置稀疏更有利于混凝土开裂的控制.

英文摘要：

In order to study the shape and propagation pattern of the cracks in concrete component under bending moment, 48 groups of concrete components were made and the propagation pattern of the cracks at mid-span of component was studied experimentally. The surface shape and number of the pre-buried steel bar and the thickness of steel-bar covering layer were considered as the component being made. The result of the study showed that the cross-sectional shape of the crack would be approximate wedge shape under bending moment. According to the shape and depth of the cracks on both side surfaces of compo- nent, the shape and depth of internal cracks in component could be deduced approximately, so that the in- fluence of inner cracks in component on its durability and mechanical performance could be studied. The control effect of cracks in concrete with thread steel bar would be better than with round steel bar and with double steel bars would be better than with single steel bar, so that within a certain range, a denser layout of reinforcements would be more advantageous to concrete cracking control than the sparser one.