Numerical study on seismic force modification factors of hybrid light wood frame structures connected to a stiff core

摘要

Seismic force modification factors of structures are specified in building codes or design standards based on structural materials and types of lateral load resisting systems (LLRSs). For a hybrid building system consisting of multiple structural materials and/or more than one type of lateral load resisting systems, the National Building Code of Canada requires that the lowest value of seismic force modification factors of these LLRSs be assigned for the seismic design of the whole building. This requirement is conservative and in need of a review. In this project, the seismic force modification factors of hybrid building systems were investigated through numerical modeling analysis. These hybrid buildings consist of a mid-rise light wood frame sub-system connected to a reinforced masonry core sub-system by a ductile connection. Incremental dynamic analysis was conducted on these hybrid buildings using commercial software, ABAQUS, together with a subroutine that describes the hysteretic performance of the sub-systems and their inter-connections with the Bouc-Wen-Baber-Noori model. Results show that a value larger than the lower value of the two sub-systems can be assigned for seismic design of these hybrid buildings. In this study it was demonstrated that meaningful relationships exist between the seismic modification factors of a hybrid structure and the mechanical characteristics, including the relative strength and ductility, of the sub-systems and their inter-connections.