Evaluating the Ramberg–Osgood Model for nonlinear moment–curvature analysis of reinforced concrete beams

This paper improves the prediction of the nonlinear moment-curvature Characteristics of Reinforced concrete beams by using the Ramberg-Osgood model. Develop an integrated analytical (closed-form) moment–curvature framework based on the Ramberg–Osgood function, which provides a smooth (continuous) elastic-to-plastic transition for steel. At the same time, concrete degradation is captured progressively through cracking and crushing using section analysis with equilibrium and strain-compatibility conditions. The model was validated through two extensive investigations of ultimate moments measured in laboratory tests. The Ramberg-Osgood model provides better predictions of ultimate moments than IS 456-2000 and achieves more than 28% Improvement in the average difference between predicted and actual ultimate moments, with a coefficient of determination (R2) greater than 0.98. The results demonstrate that the Ramberg-Osgood model can accurately describe the significant phases of reinforced concrete section behavior-concrete cracking, steel yielding, and post-yield hardening- thereby providing a more reliable method of analyzing Reinforced Concrete Flexural Performance through a nonlinear analysis than the traditional IS 456:2000 approach.