PSI - Issue 73

Pavel Dobeš et al. / Procedia Structural Integrity 73 (2025) 1–8

2

2

Pavel Dobeš/ Structural Integrity Procedia 00 (2025) 000–000

studs and transferring vertical loads but also in transferring horizontal loads and providing horizontal stiffness of the entire timber building. Currently, the diffusely open system of the outer wall composition represents the prevailing solution of walls in timber buildings, where the lightweight frame structure is sheathed by one-sided OSB boards, which are attached with metal staples. The valid European standards for the design of timber structures Eurocode 5 assume a vertical orientation of these boards. Two simplified methods are given in the standard to analyse the wall diaphragms and determine their horizontal load-carrying capacity - whether sheathed on one side or on both sides (Peterson 1983, Akerlund 1984, Källsner et al. 1984, Källsner et al. 1984). However, horizontally laid OSB boards with the tongue-and-groove joints can be also found in the practical application. OSB boards are attached to the supporting frame with metal staples, or possibly are also provided with glued tongue-and-groove joints between boards. This solution is not supported by the European standard for the design of timber structures. The aim of the paper is a comparison of the horizontal load-carrying capacity (racking resistance) and stiffness of different wall panel systems with one-sided OSB sheathing, using experimental tests on several large-scale specimens. The test results are then compared with the results from numerical models and analytical calculation based on the standard. In practical applications of timber buildings, especially in Central Europe, construction companies often adopt simplified sheathing techniques that are not fully supported by current design standards. One such commonly used method involves the horizontal installation of OSB boards without glued tongue-and-groove joints. This approach is frequently applied due to its simplicity and speed of construction (Alinoori et al. 2020, Gattesco et al. 2016, Sadeghi et al. 2018), despite the fact that it lacks normative backing in the European standard for timber structures. During field visits and consultations with contractors, the authors encountered several buildings utilizing this non-standard sheathing configuration. This observation served as the primary motivation for the presented research. The aim was to experimentally verify whether such construction practice can be considered structurally safe and whether it provides adequate horizontal load-carrying capacity and stiffness comparable to standard-compliant methods. 2. Materials and Methods 2.1. Description of testing specimens of wall panels Six specimens of timber wall panels with a length of 5 m and a height of 3 m were manufactured for the experimental testing. Three different types of wall panels were tested, each differing in the method of OSB sheathing. Each panel consisted of nine vertical studs with an axial spacing of 625 mm (respectively 595 mm for the outer studs) with regard to the dimensions of the OSB boards. The panels were provided with continuous horizontal top and bottom plates, to which the studs were attached using screws. Spacer elements, placed 500 mm below the top plate between continuous studs, were included in the case of two specimens. These spacer elements served to attach the sheathing and keep a continuous shear flow in the panel, in accordance with the German standard for the design of timber structures, DIN 1052. All studs, top/bottom plates and spacers were made of KVH profiles with a cross section of 60/120 mm, strength grade C24. The one-sided sheathing consisted of EGGER OSB 3 boards with a thickness of 15 mm. Two wall panels were made with vertically oriented OSB boards of 1250/2500 mm, with one horizontal joint at the location of the spacer element – designation B01 (see Fig. 1a). The other four wall panels were constructed with horizontally oriented OSB boards of 675/2500 mm, using tongue-and-groove horizontal joints (see Fig. 1b). The horizontal tongue-and-groove joints were glued with D4 Profi waterproof polyurethane adhesive in two of these specimens – designation A02. No glue was used for the two remaining specimens – designation A01. The OSB boards were attached to the supporting frame made of KVH profiles using metal staples with a leg length of 50 mm and a rectangular cross-section of 1.44/1.57 mm. The staple spacing was approximately 50 mm around the perimeter of the panel and 100 mm for the intermediate studs. The legs of the staples, with a minimum tensile strength of 900 MPa, are characterized by their high withdrawal capacity which is enhanced by the adhesive coating material. This coating is activated during application with a pneumatic stapler.