Title:
Performance of Open Double Stirrups as Punching-Shear Reinforcement
Author(s):
Aaron Nzambi, Denio Oliveira, and Pedro Silva
Publication:
Structural Journal
Volume:
121
Issue:
6
Appears on pages(s):
145-159
Keywords:
anchoring; flat plate; open double stirrups; punching; shear reinforcement
DOI:
10.14359/51740870
Date:
11/1/2024
Abstract:
This study experimentally evaluated the mechanical performance
of a new type of punching-shear reinforcement in five bidirectional
reinforced concrete slabs subjected to symmetrical loading. The
proposed shear reinforcement model consists of double-layered
open stirrups anchored to the flexural reinforcement, installed
after the longitudinal bars have been positioned, simplifying the
construction process. The main variables were the transverse
reinforcement ratio and the inclination of shear reinforcements. It
was found that the higher the reinforcement ratio and the inclination angle, the higher the shear strength, as expected. The open double-stirrup shear reinforcement provided more displacements and increased the punching-shear capacity by up to 36% and 40%, respectively, for vertical and inclined stirrups. Although closed stirrups are still widely used in construction, the proposed solution with open double stirrups demonstrated clear gains in punching-shear resistance, indicating their potential for practical use as reinforcement in slab-column connections. In addition, a comparison with theoretical punching-shear strength predictions from ACI 318, Eurocode 2, and ABNT NBR 6118 codes revealed conservative estimates with ACI 318, while ABNT NBR 6118 showed better accuracy.