Citation: Dobes, P.; Lokaj, A.;
Mikolasek, D. Load-Carrying
Capacity of Double-Shear Bolted
Connections with Slotted-In Steel
Plates in Squared and Round Timber
Based on the Experimental Testing,
European Yield Model, and Linear
Elastic Fracture Mechanics. Materials
2022, 15, 2720. https://doi.org/
10.3390/ma15082720
Academic Editor: Alberto Sapora
Received: 16 March 2022
Accepted: 5 April 2022
Published: 7 April 2022
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Article
Load-Carrying Capacity of Double-Shear Bolted Connections
with Slotted-In Steel Plates in Squared and Round Timber
Based on the Experimental Testing, European Yield Model,
and Linear Elastic Fracture Mechanics
Pavel Dobes
1,2,
* , Antonin Lokaj
2
and David Mikolasek
2
1
Centre for Building Experiments and Diagnostics, Faculty of Civil Engineering, VSB-TU Ostrava,
708 00 Ostrava-Poruba, Czech Republic
2
Department of Structures, Faculty of Civil Engineering, VSB-TU Ostrava,
708 00 Ostrava-Poruba, Czech Republic; antonin.lokaj@vsb.cz (A.L.); david.mikolasek@vsb.cz (D.M.)
* Correspondence: pavel.dobes1@vsb.cz; Tel.: +42-073-224-2042
Abstract:
Nowadays, the use of timber as a building material is gaining more prominence. When
designing timber structures, it is necessary to pay increased attention to the design of their connections.
The commonly used connections are dowel-type connections, which are often used in combination
with steel plates slotted into cut-outs in timber members. The presented paper deals with the behavior
of double-shear bolted connections of squared timber and round timber with slotted-in steel plates.
Several variants of connections with different distances between the fastener and the loaded end
were selected for the experimental testing. A total of six types of test specimens were made from
spruce timber, for which their selected physical properties were determined and evaluated before
the experimental testing. Test specimens of bolted connections were first tested in tension parallel to
the grain until failure under quasi-static loading. The connections were broken by splitting. Ductile
failure preceded brittle failure. The actual load-carrying capacities were lowest for the lowest end
distance. The load-carrying capacities for the middle and the longest end distances were comparable.
The results of the experiments were then used for comparison with calculation procedures according
to the standard for the design of timber structures and with calculations according to the theory of
linear elastic fracture mechanics. The experiments and the analytical models were supported by a
simple numerical analysis based on the finite element method.
Keywords:
load-carrying capacity; squared timber; round timber; steel plate; connection;
experimental
testing; numerical modelling; fracture mechanics
1. Introduction
Nowadays, the use of timber as a building material is becoming more important and
popular due to the increasing environmental requirements for construction. Timber is
used mainly in the construction of prefabricated houses, multistorey buildings, halls, and
more recently, engineering structures, such as bridges, footbridges, and lookout towers (see
Figure 1).
When designing timber structures, special attention must be paid to their connections.
The load-carrying capacity and stiffness of connections are often decisive for the durability
and serviceability of a structure. The influence of the connection stiffness is reflected in the
deformation of the structure and the redistribution of internal forces between the connected
elements, which fundamentally affects the static design of the whole load-carrying structure.
One of the main aims of designers is to design connections where a ductile failure precedes
a brittle failure (i.e., to design connections with the highest possible deformation capacity
to avoid unexpected failures).
Materials 2022, 15, 2720. https://doi.org/10.3390/ma15082720 https://www.mdpi.com/journal/materials
