This paper presents an experimental investigation on the use of polymer cement mortar (PCM) and steel strands wire mesh (SSWM) for strengthening damaged reinforced concrete (RC) columns. A new type of anchor device, wedge-shaped steel plate hoops (WSSPHs), was developed to maximize the resistance of the steel strands. The study aimed to analyze the impact of spacing and prestressing level on the mechanical properties of the damaged RC columns. Six columns were constructed and tested under low-cycle reciprocating quasi-static tests, including three control columns and three strengthened columns. The research focuses on the strengthening mechanism of WSSPHs and explores the influence of steel strand prestressing level and spacing on factors such as failure modes, hysteresis behavior, stiffness degradation, and cumulative energy dissipation of the strengthened columns. The test results showed that while the strength and stiffness of the strengthened specimens were not fully restored due to significant damage, the ductility and energy dissipation of the columns were improved. Moreover, columns with higher steel strand prestressing levels and narrower spacing demonstrated better strengthening effects. The study assessed the level of damage in specimens using the Park-Ang model, confirming the effectiveness of the proposed strengthening method.