钢筋混凝土有腹筋梁受剪机理试验研究

为研究钢筋混凝土有腹筋梁的受剪机理，以剪跨比、混凝土强度等级、配箍率为变量，完成了集中荷载作用下16根钢筋混凝土简支梁受剪性能试验。为了避免过高的纵筋配筋率，采用HRB600级钢筋作为纵向受拉钢筋。通过在箍筋内部开槽预埋电阻应变片测量箍筋的应变，分别得到钢筋混凝土有腹筋梁中混凝土和箍筋承担的剪力。试验结果表明：剪跨比和混凝土强度等级对混凝土和箍筋分担的剪力在总剪力中所占比例有显著影响，且二者呈相反的变化趋势；当剪跨比较小时，配箍能提升混凝土的受剪承载力，但箍筋本身承担的剪力较小，箍筋甚至不能屈服;当剪跨比较大时，斜裂缝倾角小于45°，实际与裂缝相交的箍筋数量多于按45°计算的数量，箍筋承担的剪力增大。与无腹筋梁相比，大剪跨比（剪跨比为3）有腹筋梁中混凝土承担的剪力减小。在试验研究的基础上，收集了国内外369根有腹筋梁受剪承载力的试验数据，采用统计分析方法得到了有腹筋梁受剪承载力计算公式，其较GB 50010—2010《混凝土结构设计规范》计算公式更加合理，计算结果也偏于安全。

Experimental study on shear mechanism of reinforced concrete beams with stirrups

Taking shear span ratio, concrete strength and stirrup ratio as variables, shear tests of 16 simply supported reinforced concrete beams under concentrated loads were conducted to study the shear mechanism of reinforced concrete beams with stirrups. HRB600 was used as longitudinal tensile rebar to avoid the high ratio of longitudinal reinforcement. Through embedded resistance strain gages inside the slotted stirrups, the shear force of concrete and stirrups can be obtained by measuring the shear capacity of the stirrups. The test results show that the shear span ratio and the strength of concrete have significant effects on the proportion of the shear force shared by concrete and stirrups in total shear force, and the two variation trends are opposite. When the shear span ratio is relatively small, the stirrups can improve the shear bearing capacity of concrete, but the shear force contributed by stirrups is small, and even cannot reach their yield strength. When the shear span ratio is relatively large, the inclination angle of the inclined crack is less than 45°, the actual number of stirrups intersecting the crack is more than the number calculated according to 45°, and the shear force contributed by the stirrups is larger. Compared with the beams without stirrups, the shear force shared by concrete in large-span beam with stirrups is reduced. Based on the experimental research, the experimental data of 369 beams with stirrups at home and abroad were collected. And the formulas for calculating the shear capacity of beams with stirrups were obtained by statistical analysis method, which are more reasonable and safer than those proposed in GB 50010—2010 ‘Code for design of concrete structures’.