Maximum Shear Strength of Reinforced Concrete Deep Beams

Current codes limit the maximum shear strength in reinforced concrete deep beams to prevent possible sudden shear failure due to over-reinforcement. For high-rise buildings, the size of deep beams designed as transfer girders is often limited by the maximum shear strength regulations. This paper suggests that the softened strut-and-tie model can be used to determine the maximum shear strength of the deep beams with a shear span-depth ratio less than 2. It is found that there are three influential parameters of the maximum shear strength for deep beams-that is, strut inclination angle, softened concrete strength, and longitudinal tension reinforcement. Considering the softening phenomenon of cracked reinforced concrete, the use of root fc ' in the ACI 318-19 limiting equation seems appropriate for the high-strength concrete deep beams. However, the ACI 318-19 limit seems to be short of the design parameters of the strut inclination angle and the amount of longitudinal tension reinforcement.