PSI - Issue 70

Milena Carolina Derlam et al. / Procedia Structural Integrity 70 (2025) 3–10

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Fig. 3. (a) Load – displacement curves of wall panels with different screw spacing; (b) Performance parameters of OSB-sheathed CFS wall panels with different screw spacing. Fig. 4 shows the Von Mises stress distribution in both the OSB panels and CFS framing components at the point of failure. The Von Mises criterion, which predicts the onset of plastic deformation in ductile materials when the equivalent stress surpasses the yield strength, was employed to evaluate material behaviour. The red zones indicate regions of material failure, identified based on the stress – strain properties presented in Table 1. In this analysis, stress values were capped at 264.35 MPa for the CFS members, corresponding to the yield strength of steel, and at 14.1 MPa for the OSB panels, representing the ultimate tensile strength of the material. The stress distribution visualized in Fig. 4 highlights the correlation between stress concentration zones and the structural limits of the materials. The failures, indicated in red, are primarily associated with local and distortional buckling of the CFS framing, leading to screw pull-out and/or pull-over — especially at panel edges under tension and compression. This behaviour is consistent with the findings of Blais and Rogers (2006) and Yilmaz et al. (2023). Failures in the OSB panels occurred mainly due to shear at the upper edge, caused by the application of lateral displacement and tensile stress in the stud combined with panel rotation, as well as material crushing at the lower corner due to compressive force, ultimately leading to fastener failures at these critical points. These mechanisms reflect the lateral load transfer described by Rosa (2018). It is observed that, for the model with a screw spacing of 75 mm, initially failure occurs in the OSB panel due to crushing of the compressed area and rotation of the panel in the tensioned area near the fasteners, followed by local and distortional buckling. As the spacing increases, the bottom and top tracks exhibit higher stresses and local buckling of the profile, culminating in premature panel failure due to local and distortional buckling, compared to panels with smaller screw spacing. This behaviour, shown in Fig. 4, occurs because, as previously mentioned, increasing the screw spacing reduces the panel’s stiffness and maximum load capacity, indicating that the increased spacing between connectors decreases the transfer and dissipation of applied energy through the connections between the sheathing and the substructure, resulting in lower stresses in the panel and, consequently, a smaller effective tensioned area, as evidenced in the analysed images of the OSB panel. Similar collapse patterns have been reported by Lange and Naujoks (2006) and Niari et al. (2015), where failures initiate at the compressed sheathing edge, progressing through screw tilting, pull-over, and localized buckling of the CFS profiles. Baran and Alica (2012) also identified buckling near anchor points and hold-downs, along with OSB detachment due to screw tilting and upper track distortion. Additionally, the panel behaves as a quasi-rigid diaphragm, concentrating stresses at the corners and leading the bottom fasteners on the tensioned side to become the primary load-bearing elements. Once these reach their deformation limit, load redistribution causes failure of the remaining connections. These findings emphasize the complex failure mechanisms in LSF shear walls and the critical role of connector behaviour and sheathing – frame interaction in overall structural performance.