Proposed Shear Design Method for Continuous Reinforced Concrete Beams Considering Moment Redistribution

Current shear design provisions for continuous reinforced concrete (RC) beams inadequately account for the coupled effects of shear span-to-depth ratio (a/d) and moment redistribution, often leading to conservative or unsafe predictions. This study addresses this gap through an integrated approach combining nonlinear finite element modelling and full-scale laboratory testing. Eleven continuous beam models with varying (a/d) ratios and transverse reinforcement percentages were analysed using ANSYS, and three full-scale RC beams were tested under symmetrical four-point loading. Results show that reducing (a/d) increases shear strength by up to 42% but reduces redistribution capacity, while changes in transverse reinforcement ratio have negligible influence on redistribution. A new empirical equation is proposed to predict moment redistribution ratios, incorporating $a/d$ effects, with prediction errors within ±5% of experimental and numerical results. Compared with current code expressions, the proposed model offers consistently higher accuracy across a wide range of geometries. The findings provide a unified framework linking shear capacity and redistribution limits, enabling more rational and reliable shear design provisions for continuous RC beams in major structural codes.