NSM-CFRP混凝土加固界面应力理论解析

摘要

目的 研究内嵌式碳纤维(NSM-CFRP)加固混凝土粘结界面的脱粘机理,并且预测界面的剥离强度.方法 以微元理论为基础,建立了NSM-CFRP与固化环氧树脂胶层及混凝土粘结界面应力的控制方程.通过设定的粘接应力-滑移关系,对界面失效全过程进行了分析.CFRP与固化环氧树脂胶层及混凝土粘结界面的受力破坏过程划分为3个阶段:弹性阶段、弹性软化阶段、软化脱粘阶段.对4组拉剪试验极限承载力的试验值与拟合后的计算值进行比较.结果 给出了FRP--混凝土界面剪应力、相对位移(滑移量)表达式以及载荷与相对位移关系.不同粘结长度得到的极限承载力解析解与拉剪试验得到的试验值进行对比吻合较好,误差在10％以内.结论 得到了计算剥离强度的表达式,极限剪应力和极限滑移量与材料的性能以及其几何因素有关,需要结合试验数据进行拟合.%In order to study near surface-mounted(NSM-CFRP) concrete bonding interface debonding mechanism and prediction of the interfacial peel strength,the control equation of bonding interface stress for CFRP plate and the cured epoxy resin layer and concrete is established based on the theory of infinitesimal.By setting the bond stress-slip relationship,the whole process of the failure of the interface have been analyzed.The failure process of bonding interface for CFRP and cured epoxy resin layer and concrete can be divided into three stages:elastic stage,elastic softening stage,softening debonding stage.Based on the interface control equation,the expressions of the bond slip and shear stress and the corresponding load and displacement(relative slip)of each stage were established through comparison the experimental results of the ultimate bearing capacity of the four group tensile shear tests with the calculated values.The theoretical calculation results are in good agreement with the experimental results,and the error is less than 10％.The expression for calculating the peel strength is obtained.Limiting shear stress and ultimate slip amount are related to material properties and the geometrical factors and need to makes the fitting with the experiment data.The results show that,theoretical analysis has good precision.