Seismic Ductility Evaluation of Shear-Deficient RC Frames Strengthened by Externally Bonded CFRP Sheets

The current study investigates the seismic performance of the Reinforced Concrete (RC) portal frames with emphasizing on the shear failure at the beam-column junction. Fibre Reinforced Polymer (FRP) is excessively used to restore RC flexural components as beam and columns. Here, the main interest is focus on the ductility and strength enhancement of CFRP retrofitted shear-critical parts of RC frame under a successively lateral cyclic loading. Two types of FRP strengthening schemes, U shaped Wrap (UW) and L shaped Wrap (LW), is used as external bonded sheets. Numerical simulation is conducted using LS-DYNA FE software, so the results in terms of load displacement are validated with the experimentally measured specimens. The crack pattern in the critical region, joint area, due to the shear deficient strength, is studied in details for both control and retrofitted specimens. The failure mode is identified because of the most probable damage type, e.g. concrete shear crack, debonding or CFRP rupture. In a conducted parametric study, the optimum stacking sequence is obtained for better performance of the RC frame subjected to the lateral cyclic loading. In this direction, the overall energy dissipation and joint ductility assessment are calculated.