Issue 39

A. Lokaj et alii, Frattura ed Integrità Strutturale, 39 (2017) 56-61; DOI: 10.3221/IGF-ESIS.39.07 56 Focussed on Modelling in Mechanics Comparison of behaviour of laterally loaded round and squared timber bolted joints Antonín Lokaj, Kristýna Klajmonová VŠB – Technical University of Ostrava, Faculty of Civil Engineering, Department of Structures, L. Podeště 1875, 708 33 Ostrava-Poruba, Czech Republic antonin.lokaj@vsb.cz, http://orcid.org/000-0003-2248-1848 kristyna.klajmonova@vsb.cz A BSTRACT . In the current European standards for design of timber structures, the issue of timber-to-timber joint type is addressed only to squared timber, which makes the pinpointing of the round timber bolted joints load carrying capacity near-unfeasible due to the insufficient support in the current standards. There have been made series of tests of round timber joints in different inclinations of the loading force and also the reference tests of squared timber joints to compare the behaviour of this type of joints. Mechanical behaviour of the round and the squared timber bolted joints was tested in the laboratory of the Faculty of Civil Engineering in Ostrava. This paper presents results of static tests in tension at an angle of 0°, 90° and 60° to the grain of squared and round timber bolted joints. Load carrying capacity was determined according to the applicable standards and theories of fracture mechanics. The test results of laboratory tests were then compared with the results of theoretical calculations. K EYWORDS . Round timber; Bolt; Joint; Load carrying capacity. Citation: Labudkova, J., Cajka, R., Numerical analyses of interaction of steel-fibre reinforced concrete slab model with subsoil, Frattura ed Integrità Strutturale, 39 (2017) 56- 61. Received: 11.07.2016 Accepted: 14.09.2016 Published: 01.01.2017 Copyright: © 2017 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION he strength of wood varies depending on the force direction relative to the orientation of the grains. The highest value reaches the tensile strength parallel to the grains, the average value indicates 120 N  mm -2 . This high strength is mainly due to the shape of cells and fibrous cell wall structure. Tensile strength perpendicular to the grain is, on the other hand, the smallest strength of wood at all. The average tensile strength perpendicular to the grain is in the range between 2 N  mm -2 and 5 N  mm -2 . This corresponds to 1/20 of the tensile strength of the wood parallel to the grain [1]. Low value of tensile strength perpendicular to the grain is caused by orientation of the binding forces. Hydrogen bonds and van der Waals forces connect grains in the transverse direction. The tensile stress of timber perpendicular to the grain is desirable in use in the support structure. This paper focuses on the behaviour of round timber bolted joints. In the current European standards for the design of timber structures [2], the issue of timber-to-timber joint type is addressed only to squared timber, which makes the T