Flexural Strengthening of Columns with CFRP Composites and Stainless Steel: Cyclic Behavior

Abstract

This study presents the testing, completion, and analysis of different external strengthening systems applied to rectangular reinforced concrete columns with rounded corners. The experimental study included confinement strengthening with carbon-fiber-reinforced polymer (CFRP) sheets, longitudinal strengthening with CFRP laminates and confining CFRP jacket, longitudinal strengthening with stainless steel bars and confining CFRP jacket, tested column until reinforcing steel failure, repair and CFRP confining jacket, and longitudinal strengthening with stainless steel bars. The analysis of the experimental results included lateral load-displacement relationship, energy dissipation, ductility, and curvature damage assessment classifications. It was concluded that the use of external longitudinal strengthening combined with CFRP confinement is effective for enhancing performance and is viable in terms of execution. The load capacity increase due to strengthening reached 36–46% with good ductile behavior (failure was reached at 4.4% drift ratio). Despite some differences between CFRP laminates and stainless steel, all columns presented moderate degrees of damage between 1 and 2% drift ratio and minor damage degree until 1% drift ratio.