Title: Maximum Shear Strength of Reinforced Concrete Deep Beams

Author(s): Shyh-Jiann Hwang, Yu-Hsuan Yang, and Yi-An Li

Publication: Structural Journal

Volume: 118

Issue: 6

Appears on pages(s): 155-164

Keywords: deep beam; force-transfer mechanism; maximum shear strength; strut-and-tie model

DOI: 10.14359/51733076

Date: 11/1/2021

Abstract:
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 √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.