Experimental and Numerical investigations on the cyclic load behavior of beams with rectangular web openings strengthened using FRP sheets

This study assesses experimentally and numerically the cyclic loading response of reinforced concrete beams with web openings and shear-flexure strengthened carbon fiber reinforced polymer (CFRP) sheets using an external bonded technique. The influence of the beams on the reverse cyclic effect including the parameters of the hysteretic failure modes, stiffness degradation performance, energy dissipation, pinching width ratio, and ductility, are discussed. A numerical approach is employed to evaluate an innovative rectangular web opening and external bonding strengthening with an FRP sheet. A numerical model was used to validate the results of the tested specimens. Appropriate simulation techniques, which characterize the properties of constitutive materials, and a concrete damaged plasticity model were used for modeling development. Further, they are incorporated to apply models with new parameters. The results indicated that the use of CFRP as a strengthening system around the opening can significantly improve the overall stiffness capacity and beam behavior under cyclic loading. In particular, the increase in the load-carrying capacity over the control beam reached 63.43% for the beam with an opening in the shear zone and 73% for that with an opening in the flexural zone. The load-displacement hysteresis loops of the tested specimens were compared with those simulated by numerical models. Good convergence between the predicted and measured results was observed under all cyclic loading rates.