Performance Comparisons of External Strengthening Methods for Deficient RC Frames

This study reports the experimental findings on the upgrading of deficient reinforced concrete frames with externally installed structural components. Specimens strengthened with an external reinforced concrete shear wall, external steel frame, steel plate shear wall, and one as-built reference portal frame specimens having a 1/3 scale were tested under constant gravity load and increasing cyclic displacement excursions. The RC frames had deficiencies such as low concrete compressive strength (8MPa), lack of transverse reinforcement detailing at potential plastic hinge regions and beam-column joints that mimic the existing deficient building stock in Turkey. The test results showed that the external upgrading can increase the lateral stiffness and strength allowing a minimum of 3% drift ratio. On the other hand, it was found that the cyclic behavior of specimens including pinching and energy dissipation capacities was found to be quite different for different strengthening methods.