Seismic Analysis of Hybrid Steel Moment Frame CLT Shear Walls Structures

Abstract

Moderately ductile steel moment frames (SMF) are a common lateral load resisting system (LLRS). They allow for a flexible architectural design for low- and mid-rise buildings but become uneconomical for high-rises due to the large member sections to satisfy the drift requirement. In contrast, lightweight cross laminated timber (CLT) shear walls provide adequate stiffness for resisting lateral loads and controlling drift in high-rise construction. A hybrid structural system combining SMF with balloon-type CLT shearwalls offers an innovative solution for economic and sustainable LLRS for mid- to high-rise buildings. In the research presented in this paper, three hybrid buildings (8-, 12-, and 16-story tall) were designed for the seismicity of Vancouver, Canada, and their performance was compared with benchmark SMF buildings. Ductile connections were used for joining the CLT panels to the steel frame and as hold-downs. The overstrength- and ductility-related force reductions factors of the hybrid system were developed based on the FEMA P695 approach. Nonlinear static and time history analyses were carried out to evaluate the structures’ seismic performance. In the hybrid systems, the use of steel was reduced by 40%–50%, and the maximum interstory drifts were reduced by up to 60% compared with the SMF buildings, demonstrating the potential of combining CLT shear walls with conventional SMF systems.