Title:
Maximum Shear Strength Limits for Reinforced Concrete Walls (Prepublished)
Author(s):
Jung-Yoon Lee and Min Jae Kang
Publication:
Structural Journal
Volume:
Issue:
Appears on pages(s):
Keywords:
maximum shear strength limit, over-reinforcement, reinforced concrete (RC) walls, shear failure
DOI:
10.14359/51745490
Date:
12/19/2024
Abstract:
Reinforced concrete (RC) structure design codes stipulate various design limits to prevent the brittle failure of members as well as ensure serviceability. In the structural design of RC walls, the maximum shear strength is limited to prevent sudden shear failure due to concrete crushing before the yielding of shear reinforcement due to over-reinforcement. Despite the increase in wall shear strength provided by a compression strut, the maximum shear strength limit for walls in the ACI 318-19 code is the same as the maximum torsional strength. Consequently, the shear strength of large-sized walls with high-strength concrete is limited to an excessively low level. The ACI 318-19, Eurocode 2, CSA-19, and JSCE-17 standards provide similar equations for estimating wall strength, but their maximum shear strength limits for walls are all different. In this study, experimental tests were conducted on nine RC wall specimens to evaluate the maximum shear strength. The main variables of the specimens were the shear reinforcement ratio, compressive strength of concrete, and the failure mode. The experimental results showed that the maximum load was reached after the yielding of shear reinforcement even when the shear reinforcement ratio was 1.5 times higher than the maximum shear reinforcement ratio specified in the ACI 318-19 code. In addition, the measured shear crack width of all specimens at the service load level was less than 0.42 mm (0.017 in.). The shear strength limits for walls in the current codes were compared using 109 experimental results failing in shear before flexural yielding or shear friction failure, assembled from the literature. The comparison indicated that the ACI 318-19 code limit underestimates the maximum shear strength of walls, and it particularly underestimates the maximum shear strength of walls with high-strength concrete or barbell-shaped cross-sections. Additionally, this study proposes an equation for estimating the maximum shear strength limit of walls based on the truss model. The proposed equation predicted the maximum shear strength of RC walls with reasonable accuracy.
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