Failure behavior of Strengthen reinforced concrete columns under effect of static load

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Introduction: This study aimed to present a rapid and effective repair method using Cempatch and carbon fiber-reinforced polymer (CFRP) for reinforced concrete (RC) columns affected by seismic events.Methods: The study included both experimental and theoretical components. The experiment involved casting and testing thirteen 900 mm long reinforced concrete columns with identical longitudinal steel reinforcement and a cross-section of 200 x 200 mm. An axial compressive load (N) was applied to all specimens, starting from zero and increasing until failure. The columns were divided into four groups, each containing a control column. Three damaged columns in each group were repaired with Cempatch and different levels of CFRP. The theoretical analysis utilized ANSYS software (version 14) for simulation.Results: The experimental results showed that the failure pattern shifted from the repaired areas to the unrepaired ones as the number of CFRP layers increased. This indicates that the restoration materials efficiently deflected stress and enhanced the load-bearing capacity of the columns. Finite element analysis results showed strong agreement with the experimental findings, with final load differences of 17.3% and 0.9%, respectively. The tests demonstrated a 148.7% increase in ultimate load with additional CFRP layers, and a 30.3% rise in the number of repaired faces. However, repairs near the center of the columns yielded less favorable outcomes than those at the top.Conclusions: The study confirms that using Cempatch and CFRP significantly improves the seismic resistance of RC columns, with optimal repair outcomes achieved with CFRP layers applied near the top of the columns.