Maximum Amount of Shear Reinforcement of Reinforced Concrete Beams

In current practice code, ACI 318 only recognizes single shear failure mode, which is shear tension failure in B – region because ACI 318 conservatively prevents shear compression failure by putting the empiric limitation on shear strength provided by reinforcement. This empiric limitation derives indirectly the maximum amount of shear reinforcement, which lacks of physical meaning.
In this research, twelve RC beams were tested to verify Kuo et al. model then proposed an analytical model that recognizes shear tension and shear compression mechanism. The shear tension mechanism simply follows ACI 318, while shear compression mechanism is based on Softened Strut-and-Tie. In addition, other well known analytical models, such as: Fixed-Angle Softened-Truss Model (FASTM), Simplified Modified Compression Field Theory (SMCFT), and Variable Angle Truss Model(8) are used as comparison.
Furthermore, the maximum amount of shear reinforcement of RC beams can be obtained. The proposed maximum amount of shear reinforcement has clear physical meaning which is the balance condition of failure between shear tension and shear compression. A rational general governing equation of maximum amount of shear reinforcement, which satisfies equilibrium, compatibility, and constitutive, is derived as well for the design implementation.