A novel loading arrangement to evaluate EB-FRP strengthening schemes

The present study investigates the force transfer mechanisms for external bonded (EB) FRP layers/strips attached on Reinforced Concrete (R/C) members with or without anchorage systems. The EB-FRP open hoop strips are utilized to upgrade either the shear or the flexural capacity of R/C structural elements. This type of retrofitting is necessary for R/C structures designed with less stringent seismic loading conditions than those currently required. The combination of anchoring systems together with EB-FRP strips is mandatory in those cases that the debonding mode of failure has to be avoided. This research is proposing a loading arrangement, utilizing specimens with realistic geometry, for the evaluation of the efficiency of the strengthening scheme, a combination of EB-FRP strips with or without the use of an anchoring system. In all codes and norms, the use of anchoring system is proposed and allowed for driving the mode of failure to the fracture of the FRP strip. Despite this fact the code provisions are not proposing a specific anchoring system, they are not proposing a methodology to prove that the anchoring system is efficient and transfers safely the loads form the FRP to the R/C element. The proposed, novel loading arrangement is allowing the application of the demanded, imposed by the design, forces onto the prototype R/C prismatic specimen, where the desired instrumentation can be placed for capturing in detail the overall behaviour of the strengthening scheme (FRP strips combined with anchorage) up to failure. Finally, typical applications are also presented.