Experimental study on shear strengthening of steel beams using CFRP strips

Steel structures are one of the most used type of structures. Some of the steel structures may need to be strengthened due to different reasons. There are different methods for strengthening of this kind of structures. In recent years, strengthening of steel structures using Fiber Reinforced Polymers (FRP) has been most interested. This study investigates the shear strengthening of steel beams using one and both sides strengthening of the web by different angles of Carbon Fiber Reinforced Polymers (CFRP) strips. Five specimens were investigated in laboratory experimentally. The test method was four-point bending approach. The load was applied on a connector loading beam by a hydraulic jack, then the load was applied on the main beam through two equal point loads. The beams had two simple supports at the both ends. The loading type was the static gradual loading type. The dimensions of the beams were chosen in the way that beams behave most in shear. This means that beams fail first due to shear stress. One beam was not strengthened, and two beams were strengthened using vertical strips on one or both sides of the web, and two remained beams were upgraded using diagonal strips. Results of this research indicates efficiency of CFRP strips for increasing load-bearing capacity of the beams. Strengthening using diagonal strips on both sides of the web demonstrated the most increment in load-bearing capacity.