NSM Rebar and CFRP laminate strengthening for RC columns subjected to cyclic loading

• An experimental program is achieved to investigate the benefit gained from strengthening cracked RC columns for seismic loads.
• The two strengthening techniques used are NSM rebar and CFRP laminates.
• Deflection response curve, yield and ultimate load capacities, dissipated energy, initial stiffness degradation, and ductility ratio are denoted and examined for each test column specimen.
• Visualized Crack patterns and fracture modes are enhanced for the strengthened columns.

An experimental program is achieved in this study conducted of three reinforced concrete column-stub specimens tested under increased cyclic lateral load to show the enhancement gained from using two well-known external strengthening techniques, which are NSM rebar and CFRP laminate, applied to partially cracked columns. Test data indicates that both of these strengthening techniques are efficient to enhance the overall behavior of the retrofitted columns like crack pattern, yield and ultimate cyclic load capacities, ductility ratio, dissipated energy capacity, initial stiffness degradation, and fracture mode. Strengthening Using CFRP laminates showed better enhancement in crack formation and propagation, while using MSN rebar showed better enhancement in load capacities, ductility ratio, and dissipated energy. Therefore, using NSM rebar may be a better choice for retrofitting and strengthening such cracked reinforced concrete columns that may be subjected to seismic event conditions.