Development of One-Way Shear Design Provisions of ACI 318-19 for Reinforced Concrete

Relationships in ACI 318-14 for calculating the concrete contribution to shear resistance ([V.sub.c]) in reinforced concrete (RC) members (that is, non-prestressed) have been replaced in ACI 318-19 by one general relationship that considers the combined effects of member depth, percentage of longitudinal reinforcement, and the effect of axial stress on predicted shear strength capacity. This new relationship is [V.sub.c] = [(8[[lambda].sub.s][lambda][[[rho].sub.w]].sup.1/3][square root][f'.sub.c] + [N.sub.u]/[6[A.sub.,g]])[b.sub.w]d, where [[lambda].sub.s] is a size effect factor equal to [square root] (2/[1 + d/10])] that accounts for a reduction in shear stress capacity with increasing member depth. The frequently used expression in ACI 318-14, [V.sub.c] = 2[lambda][square root][f.sub.c'bwd], may continue to be used in members containing at least the minimum level of shear reinforcement. The one-way shear provisions for prestressed concrete (PC) members were not changed in this code cycle. The primary basis for the new RC provisions are test results compiled in databases developed and analyzed over the past two decades through a collaboration of Joint ACI-ASCE Committee 445, Shear and Torsion, and the German Committee for Structural Concrete (DAbStb). The process for developing these new provisions included an invitation to the ACI community to suggest new one-way shear design provisions. These suggestions were discussed within Joint ACI-ASCE Committee 445, and then evaluated and modified by ACI Subcommittee 318-E, Section and Member Strength, with consideration of their basis, accuracy, safety, ease-of-use, and range of application. Keywords: building code; database; design; experiments; shear.