Reinforced Concrete Deep Beams: Review of Load Transfer Mechanisms, Shear Behaviour, Analytical Models, and Design

Abstract

Deep beams in reinforced concrete (RC) are important load-carrying elements in the design of transfer girders in tall structures, pile caps, and offshore structures. Unlike slender beams, their small span-to-depth ratios make their strain distributions non-linear, so flexure is no longer the dominant failure mode, and shear becomes the most important. Within the last few decades, research has shifted from the classical beam theory to the concept of strut-and-tie models (STM) and the mechanics of arch action, which explain the actual manner in which loads are carried by these members. This paper reviews this development systematically. It addresses the shear span-to-depth ratio (a/d), size effect, the concrete compressive strength, and web reinforcement system arrangement as the primary controlling parameters before comparing the classical empirical expressions with the available analytical models, code provisions, and data-driven/machine learning predictions. At the end of the review, the gaps in design standards are emphasized, and topics are suggested for future experimental and analytical research.