ACI 318 Structural Concrete Building Code: The Need for Member Size Factor on the Shear Strength of Beams and One-Way Slabs

Abstract

The need for a size effect factor on the shear strength of reinforced concrete beams and one-way slabs without stirrups where permitted by the ACI 318-05 Code is investigated through the examination of an extensive database compiled elsewhere and thoroughly evaluated by the ASCE-ACI Joint Committee 445 on Shear and Torsion. The database is examined in this paper under the light of applicable requirements in the ACI 318-05 code in an effort to represent current practice. The main findings in this paper indicate that the requirements in Sec. 11.5.6.1(c) to a great extent invalidate the specimens with ratios of measured to calculated shear strength less than 1.0 in the database. However, there is a paucity of data on members with depths greater than 36 inches without stirrups and without skin reinforcement. Also there is a lack of information on the shear strength of beams without stirrups having a ratio of overall depth to width less than 0.5.