Investigation of the effect of strenghtening reinforced concrete beams with steel plates on the change in the strengh

In this study, the effect of strengthening reinforced concrete (RC) beams with steel plates on the change in the strength was investigated experimentally. Nine RC beams with stirrups having a shear span-to-effective depth ratio of 4.5 were tested under a concentrated load at their midspans. While one of the beams was the reference specimen, the remaining specimens formed two series of four beams strengthened with 3 mm and 6 mm thick steel plates. Each series consisted of a beam with a steel plate glued to the bottom of the beam by using epoxy, a beam with a U-shaped steel plate glued to the bottom of the beam by using epoxy and two beams strengthened with the same plates glued to the beams by using epoxy and and also bolted to the beams at their ends. A displacement-controlled loading was conducted and the midspan deflections of the beams were recorded by means of a data acquisition system. The changes in the strength based on the thickness of plate, the shape of plate and the connection type were determined and compared with each other. It was observed that the strenght of the beams increased as the thickness of plate increased and the connection between the plate and the beam got stronger, particularly at the end of the plate.