CFRP布加固无腹筋混凝土梁的抗剪作用试验研究

Experimental study on shear behavior of concrete beams without stirrups strengthened by CFRP sheet

对12根几何相似的CFRP加固无腹筋钢筋混凝土简支梁进行剪切破坏试验,分析梁深、配纤率对梁剪切破坏模式与失效机制的影响,获得了CFRP条带的全过程应变分布情况,讨论梁深和CFRP配纤率对CFRP条带抗剪贡献的定量影响,进而提出CFRP抗剪贡献的计算公式,并与试验结果及规范计算结果等进行对比分析。结果表明,梁深对CFRP布抗剪贡献影响明显,即梁深增大时,CFRP布名义抗剪强度显著降低。梁高由300 mm变化至1200 mm时,CFRP名义抗剪强度下降约50%,具有明显的尺寸效应;不同尺寸下,CFRP布名义抗剪强度均随着配纤率的增大而增大,但名义抗剪强度增大幅度随着配纤率的增大而减小,呈现出非线性增长趋势;建立的CFRP抗剪承载力计算公式能较准确地预测不同配纤率及截面尺寸下的CFRP抗剪承载能力。

The shear failure mode and failure mechanism of 12 CFRP-strengthened concrete beams without stirrups were analyzed.The stress-strain curves of the CFRP beams in the whole process were obtained.The quantitative effects of structural size and CFRP ratio on the shear strength of CFRP are discussed.Furthermore,a formula for calculating the shear strength of CFRP is proposed and compared with the test results,the test results of others and the standard results in this work.It is found that the structural size has a significant influence on the shear strength of CFRP.The nominal shear strength of CFRP decreases significantly when the structural size increases.In addition,when the beam depth changes from 300 mm to 1200 mm,the nominal shear strength of CFRP decreases by about 50%,which has an obvious size effect.Furthermore,under different cross-section sizes,the nominal shear strength of CFRP increases with the increase of CFRP ratioρf,but with the increase of CFRP ratioρf,the increase amplitude of nominal shear strength decreases,showing a nonlinear growth trend.Finally,the established formula for calculating the shear capacity of CFRP could predict the shear capacity of CFRP under different CFRP ratio and section size scientifically.