The Discrepancy in Prescriptive Shear Reinforcement Requirements for Slender and Non-Slender Beams

Presented By: Robin Tuchscherer, Northern Arizona University Description: Prescriptive shear reinforcement requirements in ACI 318 (2019) require slender beams to contain a minimum area of web reinforcement equal to 0.08% of the cross-section, while non-slender beams require 0.25%, or roughly three times as much. This discrepancy is a source of frustration among bridge engineers as it can result in a substantial increase in stirrups for large beams. This paper illustrates the discrepancy through a case study examination of a pier cap. Given the discrepancy, the objective of the study summarized in this paper is to conduct a database analysis and evaluate the effects of vertical and horizontal web reinforcement on the strength and serviceability performance of experimental test specimens. Based on the findings, the minimum web reinforcement needed to ensure a beam’s capacity is consistent with code requirements for slender beams but not deep beams, and the minimum web reinforcement needed to control crack widths is consistent with code requirements for non-slender but not slender beams.