Simulation of delamination failures in RC members strengthened with CFRP rod panels and CFRP laminates

Fiber reinforced plastics (FRPs) have become a first choice for strengthening/repairing concrete members deficient in shear, flexure or torsion. However, oftentimes, the desired increase in capacity of FRP repaired/strengthened member is not achieved due to premature failures that occur at loads lower than the loads associated with failure of constituent materials (concrete, steel, FRP). Examples of premature failures in FRP retrofitted concrete applications include (1) plate-end debonding, (2) intermediate crack induced debonding (ICID), and (3) concrete cover separation (CCS). This paper present three-dimensional finite element (FE) models developed mainly to demonstrate the capability of FE models in predicting such failures, and to serve as reference for future FE studies concerning the behavior of RC members bonded to FRP reinforcement. Five RC beams, tested in previous experimental study by the authors, are modeled. The beams include a control beam; beam strengthened with spliced CFRP rod panel, beam strengthened with spliced CFRP rod panel, anchored at panel's ends with CFRP wraps; beam strengthened with one (full-length) CFRP laminate, and beam strengthened with lap-spliced CFRP laminate system. Results, including load mid-span deflection response, strain profile along FRP length, and failure modes, showed that the presented FE models can replicate the experiments and predict the various premature failures oftentimes observed with FRP retrofitted concrete members.