基于内聚力模型的碳纤维增强复合材料加固混凝土复合受扭柱抗震性能分析

Seismic Performance Analysis of Concrete Composite Torsional Columns Strengthened with CFRP Based on Cohesion Model

碳纤维增强复合材料(CFRP)-混凝土界面力学性能是影响CFRP加固结构抗震性能的重要因素。建立了基于非线性软化力学行为可模拟CFRP加固结构黏结界面的双线性内聚力单元,考虑混凝土与钢筋的材料非线性,对CFRP加固混凝土复合受扭柱抗震性能进行了有限元分析。分析了CFRP及黏结界面的应力变化、界面破坏机制以及结构的承载力,与试验以及不考虑界面黏结滑移的有限元分析结果进行了比较,以验证方法的合理性,并改进了CFRP的布置方式。有限元分析结果表明:CFRP的拉应力、黏结界面应力与损伤变量等呈现截面中部、转角处大,CFRP交界处小的分布特点,剥离破坏随加载过程由应力大的CFRP边缘向中部扩展;有限元分析所得结构破坏过程与试验的基本一致,揭示了黏结界面退化对CFRP加固混凝土柱结构抗震性能的影响,所得各阶段最大荷载与试验结果的相对误差小于10%;不考虑黏结界面性能的退化与CFRP的剥离,则高估了强化阶段CFRP对承载力的贡献。黏结界面内聚力模型可为CFRP加固混凝土复合受扭柱抗震性能分析提供参考。

The mechanical properties of CFRP-concrete interface are important factors affecting the seismic performance of CFRP reinforced structures.A bilinear cohesive force unit based on nonlinear softening mechanical behavior was established to simulate the bonding interface of CFRP reinforced structures.Considering the material nonlinearity of concrete and rebars,the seismic performance of CFRP reinforced concrete composite torsional columns was analyzed by finite element method.In order to verify the rationality of the method and improve the arrangement of CFRP,the stress variation,the failure mechanism of the interface and the bearing capacity of the structure were analyzed.The results were compared with the experimental results and the finite element analysis results without considering the interface bonding slip.The results of finite element analysis showed that the tensile stress,bonding interface stress and damage variables of CFRP were large in the middle and corners of the section,but small at the junction of CFRP.The stripping failure expanded from the edge of CFRP with large stress to the middle during the loading process.The structural failure process obtained by finite element analysis was basically consistent with the experimental results,which revealed the influence of bonding interface degradation on the seismic performance of CFRP reinforced concrete columns.The relative error between the maximum load obtained at each stage and the experimental results was less than 10%.Without considering the degradation of bond interface properties and the stripping of CFRP,the contribution of CFRP to the bearing capacity in the strengthening stage was overestimated.The cohesive force model of bond interface could provide a reference for seismic performance analysis of CFRP reinforced concrete composite torsional columns.