钢筋混凝土简支深梁静力性能试验研究及拉压杆模型分析

Research on strut-and-tie model based on tests of simply supported reinforced concrete deep beams

通过8根混凝土简支深梁的静力试验,研究了水平及竖向配筋率、剪跨比对拉压杆模型的影响。研究结果表明:试件经历了弹性、弹塑性和破坏三个工作阶段,在支座与加载点之间出现一条或多条斜向裂缝,试件的破坏模式主要为剪切和弯剪破坏,配筋率较小的试件发生弯曲破坏,其破坏具有延性特征;随着荷载增加,支座附近出现斜裂缝并形成混凝土压杆,当压杆的配筋率增大(不超过1.5%)和剪跨比的变小,压杆强度明显提高,且试件趋于剪切破坏;配筋率(水平、竖向配筋率)不大于1.5%,压杆的最大主应力角与剪跨比的反正切角方向接近,本文建议拉压杆模型最大主应力角取54°;推导混凝土深梁的拉压杆模型受剪承载力计算公式,其计算值与试验值吻合较好。

In order to study the strut-and-tie model＇ s influence parameters including concrete strength, shear depth ratio and reinforcement ratio, etc, eight concrete deep beams were tested. The specimens experienced elasto-plastic, and damage stages. The diagonal cracks occurred between bearing and the loading point. span-to- elastic, Failure models were mainly shear and bending shear failure. The smaller reinforcement ratio specimen exhibited bending failure, and ductile characteristics. The research results show that with reinforcement ratio（ less than 1.5% ） increased and shear span-to-depth ratio reduced, the specimen failure becomes shear failure, and strut strength is improved obviously. If reinforcement ratio （horizontal and vertical reinforcement ratio） is less than 1.5%, maximum principal stress angle is similar to the arc tangent angle of shear span-to-depth 54 -degree is suggested. Based on research results and considering the ratio, and a maximum principal stress angle of horizontal, vertical reinforcement ratio, concrete strength and shear-span ratios, suggested strut-and-tie model formulas of concrete deep beams was deduced. The calculation results are in good agreement with experimental data.