Analysis On Flexural Bearing Capacity Of T-Section Reinforced Concrete Beams With Near Surface Mounted FRP Rods

This experiment consists of4T section reinforced concrete beams.To simulate the initial damage of the beams in practical engineering, the tested beams are presplitted with preloading. Two variable which are suspected influencing flexural performance of NSM FRP rods to concrete have been investigated, such as:the surface characteristics of FRP and the FRP materials. This paper focuses on the failure pattern capacity、stiffness、deformation crack distribution、the strain of the FRP rods and steel bars、bond shear stress-slip relationship. The test results show that, for the different surface characteristics of FRP, the test beams occur to different failure mode. On the different failure mode, using the bond-slip relation and the muscle-crack spacing, the different calculation methods of flexural capacity have been proposed.The results show that:When the beams embedded the round FRP rods, the reinforced beams occur the destruction of the debonding of the FRP rods from the adhesive layer of the epoxy. When the beams embedded the ribbed FRP rods, the reinforced beams occur the interface stripping damage and/or the whole cover spalling damage.The reinforcing rods’surface characteristic is an important factor of influencing the strengthened beams’bond properties and the limit bearing capacity. Embedded the round FRP rods, the bearing capacity of the reinforced beams can increase47%-53%; Embedded the ribbed FRP rods, the bearing capacity of the reinforced beams can increase about90%. When the concrete strength is53.7MPa, the bond strength of the ribbed rods is twice of the round rods’,and the GFRP rods’ bond strength is three times as much as the CFRP rods’.Before the FRP rods sliding, the reinforcing rods’surface characteristic don’t have the obvious influence of the stiffness. After the steel yielding, the stiffness of the reinforced beams embedded GFRP rods improve44.4%, and the beams with CFRP rods improve88.9%.The beams reinforced by FRP rods, could occur the stripping damage of the concrete in the beam’s concrete cover. In the design, using the current bond failure methods calculate the beams’ultimate bearing capacity, and the results are safety. The results also show that the plane cross-section assumption can be used in the analysis of the reinforced beams.