Justification of ACI 446 code provisions for shear design of reinforced concrete beams

Due to a relatively large amount of experimental evidence and recent scientific advances, it is now-generally recognized that, to ensure adequate safety margins, the size effect for designing reinforced concrete beams against shear failure must be incorporated into ACI code provisions. A purely empirical approach is impossible because the available test data, mostly obtained on small beams, need to be extrapolated to much larger beams for which tests are scant or nonexistent. Arguments for an improved code formulation are summarized, and verification by a database compiled by Joint ACI-ASCE Committee 445 is reviewed.