Effectiveness of FRP Strengthening on RC Columns with Multiple Structural Deficiencies: A Numerical Investigation

This study investigates the structural performance and shear capacity of reinforced concrete (RC) columns characterized by diverse material and detailing deficiencies. Using a numerical modeling approach for an 8-story RC building, the research evaluates the vulnerability of a critical ground-story corner column through a nonlinear static pushover analysis. The investigation systematically examines the impact of isolated variables, including low-strength concrete, insufficient transverse reinforcement spacing, inadequate concrete cover, and the use of plain bars. The analysis demonstrates that each deficiency, when evaluated independently, induces a shear demand that exceeds capacity. Furthermore, under combined deficiency scenarios, the Performance Ratio (PR) escalates to 4.17. Two primary strengthening strategies, Fiber Reinforced Polymer (FRP) wrapping and RC jacketing, were assessed for their effectiveness in restoring structural integrity. The results demonstrate that while FRP wrapping successfully reduces the PR values to safe limits (0.40–0.56) across all models, localized RC jacketing remains insufficient, with PR values exceeding the unity threshold. These findings highlight the superior efficiency of FRP in mitigating brittle shear failures in deficient RC structures and provide critical insights for element-based retrofitting practices.