materials
Article
Experimental and Numerical Investigation into Failure Modes
of Tension Angle Members Connected by One Leg
Edyta Bernatowska * and Lucjan
´
Sl˛ eczka
Citation: Bernatowska, E.;
´
Sl˛ eczka, L.
Experimental and Numerical
Investigation into Failure Modes of
Tension Angle Members Connected
by One Leg. Materials 2021, 14, 5141.
https://doi.org/10.3390/ma14185141
Academic Editors: Patryk Rozylo,
Hubert Debski and
Katarzyna Falkowicz
Received: 27 July 2021
Accepted: 3 September 2021
Published: 7 September 2021
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Faculty of Civil and Environmental Engineering and Architecture, Rzeszów University of Technology,
Pozna ´ nska 2, 35-084 Rzeszow, Poland; sleczka@prz.edu.pl
* Correspondence: e_bernat@prz.edu.pl
Abstract: This paper presents the results of experimental and numerical tests on angle members
connected by one leg with a single row of bolts. This study was designed to determine which failure
mode governs the resistance of such joints: net section rupture or block tearing rupture. Experimental
tests were insufficient to completely identify the failure modes, and it was necessary to conduct
numerical simulations. Finite element analysis of steel element resistance based on rupture required
advanced material modelling, taking into account ductile initiation and propagation of fractures.
This was realised using the Gurson–Tvergaard–Needleman porous material model, which allows for
analysis of the joint across the full scope of its behaviour, from unloaded state to failure. Through
experimental testing and numerical simulations, both failure mechanisms (net section and block
tearing) were examined, and an approach to identify the failure mode was proposed. The obtained
results provided experimental and numerical evidence to validate the strength function used in
design standards. Finally, the obtained results of the load capacity were compared with the design
procedures given in the Eurocode 3
′
s current and 2021 proposed editions.
Keywords: steel angle members; lap bolted connection; numerical simulations; porous material
model; shear lag effect
1. Introduction
Hot-rolled equal and unequal angles are some of the most common structural el-
ements and are usually used as axially loaded tension or compression members. The
resistance of these angles when loaded in axial tension strongly depends on the way they
are connected. Owing to ease of manufacture and assembly, the most common form of
joining is connecting one leg by a single or double row of bolts, while the other, outstanding
leg remains unconnected. This results in weakening of the gross cross-section, formation
of eccentricities, and the occurrence of a shear lag phenomenon defined as non-uniform
tensile stress distribution in the vicinity of a connection, produced by applying local force
on the joint.
Numerous experimental studies have been conducted to assess the load capacities of
such connections. Munse and Chesson [1], Kulak and Wu [2], and Munter and Bouwman [3]
conducted tension tests on a wide range of angles. The observed failure modes were
described as bearing failure, shear failure of the bolts, and net section failure of the angle.
Based on these tests, a few empirical equations were proposed to calculate the net section
resistance of tensioned members. Such equations allow the treatment of angles connected
by one leg as concentrically loaded without requiring time-consuming determination
of bending effects and stress concentration and taking into account the influence of the
reduced net cross-sectional area A
net
on the bending and shear lag effect, as shown in
Figure 1a.
Materials 2021, 14, 5141. https://doi.org/10.3390/ma14185141 https://www.mdpi.com/journal/materials