Performance of Reinforced Concrete Beams Retrofitted by a Direct-Shear Anchorage Retrofitting System

Reinforced concrete beams can be effectively strengthened by FRP plates or attaching steel plates on the soffit. The performance of this type of composite beam is controlled by the interaction at the steel-concrete interface. In this study, a total of three full-scale reinforced concrete beams, strengthened with steel plates in use of different types of strengthening methods, were tested, including one reinforced concrete beam without strengthening. In this program, a new simplified anchoring system (direct shear bolting-plate system) has been proposed for strengthening a reinforced concrete beam. Its behavior was compared to the available test results from the commonly used strengthening methods. The experimental results shows that this modified anchoring system is capable of effectively reducing the debonding failure between concrete and steel plates and controlling crack development after steel yielding. It was also found that the direct shear anchoring system is more effective in increasing the flexural strength of a reinforced concrete beam and reducing the longitudinal slipping between structural components, which was eventually for increasing the capability between concrete beams and steel plates to work together.