Data-driven professional factors for ACI 318 one-way shear strength

Abstract

Uncertainty is inherent in analytical models because of simplifications and approximations, and this uncertainty is referred to as the professional factor in reliability analyses context. In the past, a lack of agreement regarding the accuracy of the ACI 318 building code requirements for structural concrete one-way shear equations made meaningful calibration of a shear resistance factor for design unjustifiable. Only expert opinion estimation of professional factors was available. Recently, in the latest edition of the ACI 318, the one-way shear design equations for reinforced concrete members significantly changed. This paper describes an effort to determine data-driven professional factors that characterize the previous and new ACI 318 analytical models for one-way shear strength. The resulting professional factors were determined through analysis of the extensive joint DAfStb-ACI Committee 445-D Shear database. The proposed, data-driven professional factors are markedly different than the subjective, expert-opinion professional factors proposed in the past. Furthermore, the analyses indicate that the new ACI 318-19 one-way shear equations represent an improvement across the full range of member sizes—especially for members without shear reinforcement. Therefore, a reliability-based calibration of the ACI 318 one-way shear resistance factor using the proposed professional factors is warranted.