Shear failure is catastrophic and occurs usually without advanced warning, thus it is desirable that the beam fails in flexure rather than in shear. Many existing reinforced concrete (RC) members are found to be deficient in shear strength and need to be repaired. Deficiencies occur due to several reasons such as insufficient shear reinforcement or reduction in steel area due to corrosion, increased service load, and construction defects. Externally bonded reinforcement such as Carbon Fiber Reinforced Polymer (CFRP) provides an excellent solution in these situations.
In order to investigate the shear behavior of RC beams with externally bonded CFRP shear reinforcement, experimental programs as well as analytical studies were conducted in this research. The research consists of three parts. They are 1). Regular beams with CFRP shear strengthening; 2). Deep beams with CFRP shear strengthening; and 3). Shear damaged beams with CFRP shear strengthening. CFRP laminates of various types and configurations were applied externally to the beams as shear reinforcement.
During the present experimental investigation, a total of five 4-foot long and six 6-foot long regular RC beams and sixteen 3-foot long deep RC beams were tested to study the behavior of shear strengthening using CFRP system. All beams were loaded by a 220-kip MTS TestStar 11 testing system. Results of the test demonstrate the feasibility of using externally applied, epoxy-bonded CFRP system to restore or increase the loadcarrying capacity in shear of RC beams. The CFRP system has been found to increase significantly the serviceability, ductility, and ultimate shear strength of a concrete beam. Restoring beam shear strength using CFRP is a highly effective technique.
Based on the experiments and analysis carried out at NJIT and the results from other researchers, new analysis and design methods for both regular and deep RC beams with externally bonded CFRP shear strengthening have also been proposed as well
