Effect of Slenderness on the Behavior of Self-Compacting Reinforced Concrete Slender Columns Strengthened with Steel Jacket

Numerous factors contribute to the deterioration of reinforced concrete (RC) columns. It may be expensive and impractical to remove or replace the damaged columns. This matter is considered one of the major challenges for structural engineers. Strengthening techniques have been developed to repair and strengthen damaged RC structures. A steel jacket made of four steel angles with battens is the traditional method for strengthening RC columns This study introduced a simple, cost-effective strengthening method using thin steel plate strips (0.5 mm thick) placed both longitudinally and transversely at mid-height, about 0.25 of the column’s length. It focuses on RC slender columns that experience additional bending from secondary moments, leading to greater lateral deflection. As a result, the impact of slenderness on the performance of these columns, especially under eccentric loading, has drawn considerable interest. Six self-compacting RC slender columns were experimentally tested for the effect of this strengthening under various slenderness ratios and eccentric loads. All columns possessed a rectangular cross-section measuring 200 x 150 mm; the three columns without strengthening have different slenderness ratios (as reference) and three columns with strengthening. The experiment’s results demonstrated how the strengthening and slenderness ratio influences the behaviour of the columns. The increase in column stiffness to reduce lateral deflection was from 1.71% to 3.83%, while the increase in column capacity was from 4.25% to 5.31%. The improvement in energy absorption capacity ranged from 9.65% to 37.45%, which is evident as the slenderness ratio increases. Moreover, strengthening the columns reduced strain, caused delayed failure, and shifted the failure location. This technique offers structural engineers a reliable and safe method to effectively and economically strengthen RC slender columns.