Title:
Shear Strength of Large Beams and Foundations with High-Strength Reinforcement
Author(s):
Jerry Y. Zhai and Jack P. Moehle
Publication:
Structural Journal
Volume:
123
Issue:
1
Appears on pages(s):
171-186
Keywords:
foundation mat; high-strength reinforcement; shear; shear reinforcement; size effect; tension shift
DOI:
10.14359/51748931
Date:
1/1/2026
Abstract:
Laboratory tests of deep, lightly reinforced concrete members without shear reinforcement demonstrate that the nominal shear stress at failure decreases with increasing depth and with decreasing tension longitudinal reinforcement ratio. Design procedures for one-way shear strength in ACI 318-19 incorporate these effects, but result in relatively low design shear strengths for members with both large depth and low reinforcement ratio. To better understand the effects of depth and longitudinal reinforcement on shear strength, tests were conducted on beams with varying depth, a relatively low ratio of high-strength longitudinal reinforcement, and with either no shear reinforcement or minimum shear reinforcement. Loads were applied slowly and monotonically and included concentrated loads plus self-weight. Beam supports were either point supports, as in a beam, or uniformly distributed, similar to some foundation reactions. The test results demonstrate size and longitudinal reinforcement effects and suggest that a lower-bound unit shear strength may be applicable for the design of members with both large depth and low reinforcement ratio.
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