Experimental and numerical investigation of strengthening inadequate reinforced concrete frames with innovative precast panels

Structural strengthening applications have disadvantages such as lengthy construction times, evacuation requirements, and loss of architectural integrity. In order to address these issues, researchers have recently concentrated efforts on developing practical methods. This study presents experimental and numerical investigations into an innovative strengthening technique using precast reinforced concrete (RC) panels. The proposed method offers several advantages, including eliminating the need for evacuation, cost-effectiveness, quick implementation, reliability, and the ability to maintain functional openings. Five 1/3-scale specimens of single-story, single-span RC frames, reflecting common earthquake-vulnerable structural deficiencies, were tested. Four specimens were strengthened using precast RC panels with varying parameters, while one served as a reference without strengthening. The specimens were subjected to reversed cyclic lateral loading to simulate earthquake conditions. Numerical analyses were performed using the Abaqus/CAE software based on the finite element method. Results showed that the proposed method improved load-bearing capacity, stiffness, strength, ductility, and energy dissipation while reducing column base rotations. Specifically, it was observed that the technique increased lateral load-bearing capacity by 54% to 136% and enhanced ductility up to 44%, depending on panel configuration. Panels placed closer to columns contributed more to stiffness, while panels positioned farther enhanced ductility. Furthermore, the cumulative energy dissipation capacity up to the yielding point increased by up to 119% compared to the reference specimen, and all strengthened specimens exhibited greater plastic energy consumption. The findings from the experimental and numerical studies were highly consistent, validating each other’s results and demonstrating the effectiveness of the proposed technique in improving the seismic performance of RC frames.