Experimental Testing and Numerical Modeling of a Novel Buckling Restrained Connection for Mass Timber Structures
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Authors
Neves, Dylan Cocharro
Date
2025-05-16
Type
thesis
Language
eng
Keyword
Mass timber , Braced frames , CLT shear walls , Connections , Axial fuse , Glued-in rod , Time-history analysis
Alternative Title
Abstract
This thesis presents the concept, design procedure, and experimental testing on a new buckling restrained connection for mass timber structures. The connection combines a glued-in rod with a metallic buckling-restrained axial fuse to form a high-stiffness, high-strength, and highly ductile connection for mass timber structures when compared with conventional connection types (i.e., screws or bolts) that is also fully concealed. Furthermore, by introducing a mechanical coupler between the glued-in rod and the axial fuse, the connection becomes replaceable as the axial fuse(s) could be replaced following an earthquake given the appropriate detailing. To validate the performance of the connection, a design method is proposed and used to detail a series of connections with capacities ranging from 25 to 300 kN and axial fuse core lengths between 150 and 250 mm. The use of stainless steel as a core material to improve resistance to corrosion and improve elongation capacity is also investigated. Results of the study demonstrate that the connection can achieve its design yield capacity within 5% on average, has cyclic elongation capacities of up to 40 mm, and exhibits stable hysteretic behaviour with higherenergy dissipation capacity when compared to traditional connection types due to the lack of a pinched hysteretic response.
Following the experimental testing, a series of prototype buildings were designed in Montreal, Quebec, and Vancouver, British Columbia, two highly active seismic regions in Canada, with the goal of assessing the new connections performance in extreme loading events. A numerical model of a CLT shear wall was created in Opensees. This model was used to assess the ability of the new connection to control lateral drift of the buildings using non-linear time history analysis. Results showed that the prototype structures consistently had inter-storey drifts below the limit of 2.5% while hold-down displacements were less than 10% of the core length. Comparing the performance of a structure with the buckling restrained connection to a more traditional self-tapping screw connection demonstrated that the buckling restrained connection resulted in smaller lateral displacements by over 40% and hold-down displacement demands that were 2.4 times smaller.