Reinforcement Effects and Parametric Study of the Lateral Response of Multilayered Wood-Frame Shear Walls: An Experimental and Numerical Investigation

Abstract

In the seismic design of light-frame timber buildings (LFTBs), the use of strong shear walls (SSWs) is crucial for providing lateral resistance. While the contribution of finish layers, such as Type X gypsum wallboard (GWB), has generally been conservatively ignored, recent experimental and numerical studies have demonstrated that these finish layers can significantly enhance the cyclic lateral performance of SSWs, leading to the concept of multilayered strong shear walls (MLSSWs). The effect of the finish layers cannot be solely attributed to additional layers and fasteners. There is also an additional reinforcement effect from deeply screwed Type X GWB that prevents nails from pulling out during hysteresis cycles that has not been previously investigated. The primary objective of this study is to explore the reinforcement effect and evaluate MLSSWs across a broad range of configurations. The research combines experimental tests (monotonic and cyclic) and numerical simulations, with connection-level tests used to calibrate the numerical models. The simulations interrogate the influence of the reinforcement effect and investigate the effects of various parameters, including wall aspect ratio, number of Type X GWB layers, multilayered connection type (screwed or stapled), and overturning anchorage systems. The findings demonstrate the positive effect of finish layers on strength and stiffness. The reinforcement effect of screws and Type X GWB layers is shown to modify the response of nailed OSB-to-frame connections, preventing nail pullout and improving fatigue resistance and deformation capacity. The study shows that the other important parameters that control the strength, stiffness and deformation capacity of MLSSW are multilayered connection type and number of Type X GWB layers. This research enhances the understanding of the role of Type X GWB finish layers on the lateral response of MLSSWs for improved design and construction. This study provides essential insights for the seismic design of light-frame timber buildings. It demonstrates that finish layers such as Type X gypsum wallboard, typically used for fire protection, can significantly improve the strength and stiffness of wood-frame shear walls. This finding challenges traditional design practices that overlook the structural role of finish layers, and indicates that there is a need for updated design approaches. Our research also shows that these fire protection layers can be strategically used in multistory buildings to enhance structural efficiency under seismic conditions. This advancement has the potential to make light-frame timber buildings a more viable option than prevalent concrete structures in many countries. Additionally, it offers a comparable alternative to mass timber-based solutions, contributing to more resilient and sustainable building infrastructure.