Reinforcement of concrete beam–column connections with hybrid FRP sheet

Abstract

The paper describes the results of tests on prototype size reinforced concrete frame specimens which were designed to represent the column–beam connections in plane frames. The tests were devised to investigate the influence of fibre reinforced plastic (FRP) reinforcement applied to external surfaces adjacent to the beam–column connection on the behaviour of the test specimens under static loading. Of particular interest under static loading was the influence of FRP reinforcement on the strength and stiffness of beam–column connection. As a key to the study, the hybrid FRP composites of E-glass woven roving (WR) and plain carbon cloth, combined with chopped strand mat (CSM), glass fiber tape (GFT) with a vinyl-ester resin were designed to externally reinforce the joint of the concrete frame. The results show that retrofitting critical sections of concrete frames with FRP reinforcement can provide signification strengthening and stiffening to concrete frames and improve their behaviour under different types of loading. The selections of types of FRP and the architecture of composites in order to improve the bonding and strength of the retro-fitting were also discussed.