Seismic Design of CLT Shear-Wall and Glulam Moment-Resisting Frame Coupled Structure

Abstract

In response to the increasing need for sustainable construction materials, numerous innovative timber-based structural systems have been developed in the past two decades. While timber-based shear-walls are popular, moment-resisting timber frames have received less attention in recent studies. However, with the availability of ductile and resilient beam-column joints (BCJs), timber frames can now be effectively used either independently or in combination with others. This study explores the feasibility of a dual system, consisting of cross-laminated timber (CLT) balloon shear-wall and glulam moment-resisting frame (CLTW-GMRF), and investigates the potential interaction between the two systems under seismic loading. The building features ductile and energy-dissipative BCJs and hold-downs. A seismic design procedure, based on a targeted moment proportion (MP) between the two systems, is presented and applied on a 10-story building. The building is assumed to be located in Vancouver, Canada, and its seismic performance is examined using 30 ground motion records in OpenSees. The system’s efficiency with respect to engineering demand parameters is studied under different wall-to-frame MP values (50%–50% and 60%–40%) and ductility-related modification factors (2, 3, and 4). The study also investigates the system’s performance with two BCJs and hold-down alternatives with bilinear hysteretic and self-centering energy-dissipative responses. Given the availability of resilient connections, the result highlights that the CLTW-GMRF coupled system is a viable alternative for high-rise hybrid timber construction. Moreover, the system’s performance has significantly improved by using self-centering energy-dissipative systems. This paper unveils an innovative design approach and practical application for a CLTW-GMRF dual system. This innovative system incorporates energy-dissipative components that are designed and tested in existing literature: (1) the utilization of replaceable steel damper BCJs and buckling-restrained brace hold-downs, providing high ductility with large energy-dissipative capacity; and (2) the employment of hybrid BCJs made up of post-tensioned tendons and mild steel dissipators, along with hybrid brace hold-downs made up of pretensioned tendons and friction surfaces, which reduce residual deformations following seismic events. Utilizing these systems, the research introduces a versatile seismic design method congruent with existing codes and design standards, while offering flexibility through adjustable wall-to-frame moment proportions. The research also underlines the need for careful consideration of the interaction within the timber wall-frame systems. The implications are substantial amidst the growing trend of high-rise timber construction, aiming to fully exploit the potential of CLT and Glulam frames. Moreover, the research has the potential to serve as an essential resource for engineers aiming to optimize the sustainability and resilience of timber structures, particularly in seismic-prone regions.