Development of an Innovative Hybrid Timber-Steel Moment-Resisting Frame for Seismic-Resistant Heavy Timber Structures

This study assesses the seismic performance of a new hybrid timber-steel moment-resisting connection for mid-rise heavy timber structures. This system consists predominantly of timber members, but utilizes a steel yielding link at the beam-column joint that improves seismic performance by replacing connection components that are susceptible to brittle failure with ductile steel elements. The steel-to-timber connection was made using self-tapping screws. By localizing all inelastic behaviour to a single ductile component, design with high seismic force reduction factors becomes justifiable. Four connections were tested; a majority of the plastic rotation was localized to the link, high levels of ductility were achieved, and the steel-to-timber connections remained undamaged. A numerical study was performed on a hybrid frame using the proposed connection, and an equivalent steel-only frame. Results showed that drifts and accelerations remained within allowable limits, indicating that well-detailed hybrid connections can result in seismic performance similar to steel-only frames.