Title:
Shear Strength of Post-Tensioned Slab-Column Connections: Reevaluation of ACI 318-19 Code
Author(s):
Giwan Noh and Thomas H.-K. Kang
Publication:
Structural Journal
Volume:
121
Issue:
4
Appears on pages(s):
197-212
Keywords:
flat plate; post-tensioned (PT); prestressed; punching; shear strength; slab-column connection
DOI:
10.14359/51740575
Date:
7/1/2024
Abstract:
Compared to conventional reinforced concrete (RC) flat-plate
systems, post-tensioned (PT) flat-plate systems lack experimental
studies on shear strength, and there are no studies that have been
analyzed and collected with clear criteria (for example, calculation
of effective depth, unbalanced moment, and measured shear
strength) about experiments conducted so far. As a result, the
current ACI 318-19, Section 22.6.5, for prestressed members has
many restrictions based on the lack of experimental data on the
nominal shear-strength equation. In this study, to reevaluate the
nominal shear strength of the PT flat-plate system more reasonably
and provide a reference for future studies, a total of 120 experimental data on the shear strength of the PT flat-plate system
without shear reinforcement that have been conducted so far were
recalculated and recompiled with clear criteria (the experimental
data consists of 74 interior connections, 41 edge connections,
and five corner connections). In addition, the factors affecting
the shear strength and the validity of restrictions in the nominal
shear-strength equation of ACI 318-19 were analyzed. The factors
affecting the shear strength include: 1) method of loading; 2) presence of nonprestressed reinforcement; and 3) reinforcement ratio along the lateral load direction. The restrictions in the nominal
shear-strength equation of ACI 318-19 include: 1) fc′ ≤ 4900 psi
(34 MPa); 2) fpc ≥ 125 psi (0.9 MPa) (in each direction); 3) fpc ≤
500 psi (3.5 MPa) (average in the two directions); and 4) it is
applicable only for interior connections.