Assessment of flexural strength of slender RC rectangular beams

Slenderness effects in reinforced concrete beams are not comprehensively accounted for in the prevailing design codes of concrete. Existing recommendations are prescriptions of limiting slenderness ratios, which are semi-empirical in nature. No reduction in flexural moment capacity is recommended for beams with moderate slenderness. Experimental studies on 15 RC beams reveal that, the existing design guidelines are not sufficient to ensure gradual failure and that a reduced ultimate flexural moment capacity results in beams of moderate slenderness. A simplified formulation for evaluating critical buckling moment in reinforced concrete beams is proposed in this paper. Authors highlight a theoretical basis for limiting slenderness and based on the experimemtal results, propose a conservative reduction factor for evaluating the ultimate flexural moment capacity of RC slender beams.