PSI - Issue 73

Marek Johanides et al. / Procedia Structural Integrity 73 (2025) 38–44 Marek Johanides and Antonín Lokaj/ Structural Integrity Procedia 00 (2025) 000–000

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Nomenclature d ratio between the ultimate limit state value (ULS) and the experimentally achieved value ε ratio of deformation between different reinforcement configurations (relative to unreinforced specimen) F applied force (represented schematically in figures)

F max,d load capacity at the ultimate limit state according to Eurocode 5 F max,k load capacity at the serviceability limit state according to Eurocode 5 γ con partial safety factor for joints γ M partial safety factor for timber k ratio between the serviceability limit state value (SLS) and the test result k mod modification factor for timber properties (based on moisture and load duration) r radius of the circle on which fasteners are arranged SLS Serviceability Limit State (as defined by Eurocode 5) u maximum vertical deformation at the free end of the cross-member ULS Ultimate Limit State (as defined by Eurocode 5)

2. Description of structure The timber structural system used in the experiment was composed of a semi-rigid connection between two frame struts and a crossbar. In total, two identical construction systems were created, differing only in the type of fastener used. Experiment A employed a combination of bolts and dowels as fasteners, while Experiment B used full-threaded screws. Both the strut and the crossbar had a cross-section of 100 × 300 mm. The fastener arrangement in both experiments was identical: ten fasteners were symmetrically positioned along a circle with a radius of r = 90 mm. The layout of the connecting elements is shown in Fig. 2. The selected geometry complied with the basic requirements for edge distances and spacing between fasteners, as defined by Koželouh (2004) [ 12]. The figure also illustrates the reinforcement of individual structural segments. Reinforcement consisted of two full-threaded screws placed side by side within one segment of the structure. Each screw had a diameter of 8 mm and a length of 300 mm. The reinforcement layout was based on analytical assumptions, targeting areas of maximum tensile stress perpendicular to the grain.

Fig. 2. Deployment of fasteners.

To carry out the experiments, it was necessary to establish appropriate boundary conditions for the structure. To ensure these conditions, a steel support structure was designed, analyzed, and manufactured in the form of a steel plate