预应力碳纤维薄片加固RC梁放张后界面受力分析

Interface Behavior of RC Beams Strengthened with Carbon Fiber Laminates After Releasing Prestress

以碳纤维薄片(CFL)加固钢筋混凝土(RC)梁为研究对象,采用压梁法对CFL施加预应力,计及混凝土与CFL之间界面的软化行为,理论推导了预压力放张后界面粘结剪应力和CFL轴向正应力的分布规律,实施放张实验对界面应力的计算值进行了验证,并以界面断裂能作为剥离判据,建立了不引起界面剥离最大预压力的计算模型。实验与计算结果表明,预压力放张后,CFL轴向应力的计算值与实验值吻合较好;预压力放张后,CFL端部的界面粘结剪应力急剧增大;减小CFL的厚度或弹性模量有利于防止界面剥离的发生。

This study investigates the interface behavior of reinforced concrete（RC） beams with strengthened carbon fiber laminates（CFL） prestressed by precompressing beam.With the soft behavior of the interface,an analytical solution for the interface stress of strengthened beams with prestressed CFL after releasing precompression is presented.By regarding the fracture energy as a criterion of the interfacial debonding,a theoretical model to predict the critical prestress level of initiating debonding is proposed.Moreover,some experiments were carried out to verify the analytical solution of CFL longitudinal stress.The results show that the analytical solution of the CFL longitudinal stress is basically in agreement with that of experimental values.It is also found that an abrupt increase of the interface shear stress arises in the CFL end after releasing prestress,and the increasing of the thickness or elastic modulus of CFL is benefit for avoiding debonding on releasing prestress.