截面高度对钢筋混凝土梁裂缝分布影响的试验研究

为建立混凝土结构裂缝验算的统一公式，通过试验研究了截面高度对钢筋混凝土简支梁裂缝分布形态、裂缝间距和裂缝宽度的影响规律。根据裂缝的产生机理、延伸发展特征和宽度变化规律提出了分型统计的原则，进行各类型裂缝数量、平均裂缝间距、平均裂缝宽度及最大裂缝宽度分布规律的分型统计分析。明确了结构设计中裂缝宽度验算对应的裂缝形态特征的物理意义，即该裂缝为在后续各级荷载作用下，因开裂截面钢筋拉应力和混凝土受拉区高度的持续增大而得以持续延伸到中和轴附近的主裂缝。提出了以纵向受拉钢筋直径为变量的有效受拉截面高度的计算方法，提出了考虑截面高度与有效配筋指数耦合影响的平均裂缝间距计算模式。

Experimental study on effect of cross sectional depth of concrete beams on crack patterns

The effect of cross sectional depth of simply supported reinforced concrete beams on crack states, spacing and width of cracks were experimentally studied. The statistical method was applied to analyze the number, average spacing, average width and maximum width of cracks according to the crack patterns. The crack feature corresponding to the checking of crack width in design procedure of concrete structures was determined, it can be expressed as that the cracks maintain elongation to the neutral axis after cracking under the follow up loading, because of the increase of tensile stress of reinforcement and tensile depth of concrete in cracked cross section. The method considering the diameter of longitudinal tensile reinforcement was proposed for calculating the effective tensile depth of cross section. A model for calculating the average crack spacing with the coupling effect of cross sectional depth and effective reinforced coefficient taken into account is suggested.