The Fatigue Behavior Of Reinforced Concrete Beams Strengthened With NSM Prestressed CFRP Strips

Along with the increasing seriousness of traffic conditions and serious damage degradation of existing Bridges,the stress of the many existing bridge performance is difficult to meet the demand of force reserve,so it is necessary to carry out the reinforcement to ensure their safety and eligibility,both at home and abroad with Fiber Reinforced composite materials(Fiber Reinforced Polymer,FRP)for the bridge reinforcement has a wide range of applications.But traditional stick(Externally Bonded,EB)FRP reinforcement technique prone to easy tear of FRP and concrete interface,so in recent years the rise of the Surface layer is embedded to stick(Near Surface Mounted,NSM)FRP technology,it will be in good concrete trough a buried FRP,exponentially increase the bonding area of the specimens,enhance the bonding capacity of FRP and concrete to inhibit or even avoid the FRP and concrete stripping damage.And make full use of in order to achieve the strength of FRP,the recent emergence of prestressed NSM FRP technology got the favour of a lot of scholars abroad and exploration,and the domestic current study of prestressed NSM FRP strengthening technique is less a little.In view of this,this paper conducted a series of prestressed NSM FRP reinforcement of static load and fatigue test specimens,explore the surface under different size of CFRP prestressed post prestressed CFRP embedded lath static load performance of strengthening reinforced concrete beam and destruction form;On the basis of this expansion reinforced specimen is studied the fatigue performance of form,examines the specimen fatigue performance strengthened by CFRP prestressed size,bond length of CFRP panel,bonded CFRP end concrete protection measures,the bond stress and the influence of factors such as amplitude fatigue loading.Test results show that: under static load conditions when prestressed large specimen will show the premature end concrete tear shed,specimen ultimate load decreases with increasing prestressed reverse the trend,and the different failure modes of the specimens prestressed also changed;Specimen under fatigue load are also prone to the end of the concrete protective layer or thin layer stripping tearing failure,but this kind of destruction with the decrease of the load amplitude,the extension of bond length,bond end to u-shaped hoop constraint,or prestressed concrete slow down or avoid completely,with the decrease of the fatigue life and failure mode of the general will bring a big change.