Citation: Johanides, M.; Lokaj, A.; Mikolasek, D.; Mynarcik, P.; Dobes, P.; Sucharda, O. Timber Semirigid Frame Connection with Improved Deformation Capacity and Ductility. Buildings 2022, 12, 583. https:// doi.org/10.3390/buildings12050583 Academic Editor: Jorge Manuel Branco Received: 25 March 2022 Accepted: 27 April 2022 Published: 30 April 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). buildings Article Timber Semirigid Frame Connection with Improved Deformation Capacity and Ductility Marek Johanides 1,2, * , Antonin Lokaj 1 , David Mikolasek 1 , Petr Mynarcik 2 , Pavel Dobes 1,2 and Oldrich Sucharda 2,3 1 Department of Structures, Faculty of Civil Engineering, VSB-Technical University of Ostrava, 708 00 Ostrava, Czech Republic; antonin.lokaj@vsb.cz (A.L.); david.mikolasek@vsb.cz (D.M.); pavel.dobes1@vsb.cz (P.D.) 2 Centre for Building Experiments and Diagnostics, Faculty of Civil Engineering, VSB-Technical University of Ostrava, 708 00 Ostrava, Czech Republic; petr.mynarcik@vsb.cz (P.M.); oldrich.sucharda@vsb.cz (O.S.) 3 Department of Building Materials and Diagnostics of Structures, Faculty of Civil Engineering, VSB-Technical University of Ostrava, 708 00 Ostrava, Czech Republic * Correspondence: marek.johanides@vsb.cz Abstract: The present study deals with the innovation and the possibilities of improving the design solution of a frame connection for two selected types of fasteners. All specimens were made of glued laminated timber. Dowel-type mechanical fasteners, a combination of bolts and dowels, and full-threaded screws were used for the connection. The main goal of this research was to replace the typical solution (common dowel-type fasteners) with a more modern, faster, and easier solution in order to improve the load-carrying capacity, ductility, and deformation capacity of this type of frame connection. This article also aimed to provide a detailed evaluation of the mechanical properties of the used glued laminated timber and fasteners in order to comprehensively evaluate the research task. For the design solution, a frame connection created from a system of two struts and a partition was chosen as the basis of the experimental program. Dowel-type mechanical fasteners, as well as combinations of bolts and dowels, were used for the connection; however, in addition to these standardly used mechanical fasteners, full-threaded screws were used. The article describes the use of static destructive testing to determine the ductility of the connection, considering different variations in the strengthening of the individual segments of the mentioned connection means. In the first variation, the individual components of the frame were not reinforced in any way. In the second, the crossbar was reinforced with two full-threaded bolts. In the third, the webs and the crossbar were reinforced with two full-threaded bolts. In the article, these ductility values were compared with each other and the procedure was set by the currently valid standard. Keywords: ductility; load capacity; timber; frame connection; screws; bolts and dowels; glued- laminated timber 1. Introduction Timber is an important building material for the sustainability of the construction industry. The diagnostics of existing structures is related to the testing of their mechanical properties [1]. The current possibilities of timber processing also allow the design of multistory buildings [2] or long-span structures [3], where it is necessary to respect the experience gained from previous accidents and structural failures [4]. For timber and timber structures, the use of experimental tests of structural details [5,6] or structural parts, e.g., whole frames [7], is very important. For example, the use of numerical modeling based on the finite element method is also very important [8,9]. Interesting and important recent experiments were also presented in [10]. Buildings 2022, 12, 583. https://doi.org/10.3390/buildings12050583 https://www.mdpi.com/journal/buildings