考虑剪跨比及配纤率影响的CFRP加固剪力墙抗剪承载力计算方法

Calculation method for shear bearing capacity of CFRP-strengthened shear wall considering shear span ratio and CFRP ratio

为探究外贴碳纤维增强复合材料(CFRP)加固钢筋混凝土(RC)剪力墙的抗剪性能及作用机制,基于Hashin损伤准则建立了可以考虑CFRP-混凝土界面剥离的三维数值模型。研究了剪跨比、CFRP配纤率及加固方式对CFRP加固RC剪力墙抗剪性能的影响。研究结果表明:(1)外贴CFRP加固后有效缓解了剪切主裂缝的发展;(2)随着剪跨比的增大,CFRP加固剪力墙中CFRP条带所提供的抗剪贡献显著降低;(3)CFRP抗剪贡献并不是随着加固层数的增大而线性增长。基于模拟分析结果,从定性结论扩展至量化分析,提出了剪跨比及加固层数影响系数,并基于美国规范(ACI 440.2R-17)公式形式,进一步建立了表征CFRP抗剪贡献的计算公式。通过与试验数据的对比,发现该建议公式可以更准确的描述剪跨比、CFRP配纤率及加固方式对CFRP抗剪贡献的影响规律,建议公式预测结果与试验结果的平均绝对误差为8%,验证了建议计算方法的有效性。

To explore the shear performance and the corresponding mechanisms of carbon fiber reinforced polymer(CFRP)strengthened reinforced concrete(RC)shear walls,a three-dimensional numerical model based on the Hashin damage criteria that captures the CFRP-concrete interface debonding behaviors was developed.Using the proposed model,the influences of shear span ratio,CFRP ratio and wrapping method on the shear capacities of the CFRP-strengthened RC shear wall were investigated.It is found that:(1)The external CFRP strips effectively mitigate the development of the shear primary cracks;(2)The increasing shear span ratio reduces significantly the shear contribution provided by CFRP strips on the CFRP-strengthened RC shear walls;(3)The shear contribution of CFRP is not linearly dependent on the number of CFRP layers.From qualitative to quantification analysis,the influence coefficient of shear span ratio and CFRP layer was introduced based on the numerical calculations.Furthermore,writing in the form of the American Code(ACI 440.2R-17),a calculation formula characterizing the shear contribution of CFRP was established.By comparing with the experimental data,it is noticed that the proposed formula gives more accurate descriptions on the influence of shear span ratio,CFRP ratio and wrapping method on the shear contribution of CFRP.The average absolute error between the prediction results and the experimental results is 8%,thus,verifying the effectiveness of the proposed calculation method.