Bond Performance of Different FRP Strengthening Systems

The use of bonded fibre reinforced polymers (FRP) has gained a widespread acceptance as an excellent method for strengthening, retrofitting and upgrading of existing concrete structures. This paper presents the preliminary results of an experimental program conducted to evaluate bond characteristics of CFRP reinforcement bonded to concrete beams. A total of 24 concrete beams were constructed and tested under monotonie static loading. Three different strengthening techniques were investigated, including near surface mounted CFRP bars, strips and externally bonded CFRP sheets. For each strengthening technique, different bond lengths were considered. Design guidelines for the development length of CFRP bars, strips and sheets, used in strengthening concrete beams are proposed. Ultimate capacity as well as failure mechanism of concrete beams strengthened with different FRP systems are presented.