Perforated steel structural fuses in mass timber lateral load resisting systems

Abstract

Attention towards high-rise timber buildings has been increasing in recent years as part of the global trend of designing sustainable structural systems. Cross-laminated timber (CLT) shear walls and mass timber braced frames (TBF) are two feasible and sustainable options that can be employed as lateral load resisting systems (LLRS) to stabilise buildings against wind and earthquake loads while reducing the environmental footprints of conventional structures. Tall timber buildings using such systems have been built around the world, mainly in non-seismic or low-seismic locations and locations with regular wind loading. Their application in high seismic or wind regions requires more research on the behaviour of the systems and their components with respect to the corresponding loading, particularly in the connections. This paper presents an experimental study on the use of perforated steel plates as a dissipating energy device, also called structural fuse, to enhance structural performance during extreme loading events. Panel-to-panel connections and hold-downs within CLT shear walls and end brace connections within TBF were selected as potential locations for structural fuses. The strength, stiffness, ductility, over-strength, and failure mechanism of the perforated plate systems were determined to investigate the use of the system as a reliable energy dissipating mechanism. It was found that perforated steel plates provide a reliable yield mechanism with predictable yield and ultimate strength, and that damage in timber elements can be avoided when the fuses are combined with capacity-protected dowel-type fasteners. While the results of monotonic tests demonstrate considerable ductility for the various connections, a significant reduction in post yield dissipation is observed under cyclic loading, despite large non-pinching hysteretic curves.