OSB and GFB As Sheathing Materials for Timber-Framed Shear Walls: Comparative Study of Seismic Resistance

The paper presents a comprehensive study on oriented strand boards (OSB) and gypsum fiber boards (GFB) as sheathing materials for light-frame wall elements. The study is based on the experimental results of the research project, optimization of multistory timber buildings against earthquake impact (OptimberQuake). In the framework of this project, 20 light-frame wall elements and 58 sheathing-to-framing connections with different layouts have been tested under cyclic and monotonic loading. The experimental results have been analyzed and compared in terms of ductility, energy dissipation as well as deformation, and load-bearing capacity. Furthermore, the performance of the walls was evaluated with the probabilistic approach in accordance with current methodology. For this purpose, a simplified numerical model was used in which the walls were represented by an equivalent nonlinear shear springs. The characteristics of the springs were determined based on the experimental results wherein the response was described by a hysteretic model. As a result of probabilistic analysis, behavior factor (i.e., force reduction factor) was evaluated for walls with different types of sheathing. The analysis of the experimental results and probabilistic approach led to the same conclusions. The results show a comparable cyclic response of timber framed walls covered with OSB or GFB boards in terms of energy dissipation and deformation capacity. The probabilistic assessment also suggests that the same behavior factor can be used for both types of wall if the basic requirements regarding the minimum thickness and detailing of the connections are met. A higher value for the minimum thickness of GFB compared with OSB will be recommended.