Pinching-Free Connector for Timber Structures
Publication: Journal of Structural Engineering
Volume 147, Issue 5
Abstract
In timber structures resisting earthquakes, slender steel fasteners are traditionally employed to provide ductility in the joints. However, this is associated with pinched hysteresis loops when timber fibers are irreversibly crushed during loading cycles. A pinching-free connector (PFC) was developed to address this issue. In the PFC, crushing-induced slack is effectively absorbed through a ratcheting mechanism. Quasistatic cyclic tests verified that the PFC eliminated pinching. A stocky-fastener configuration of the PFC demonstrated improved reloading stiffness and predictability of resistance under Mode 1 behavior. This enables a smaller overstrength factor of 1.45 compared to 1.6 for conventional connections. Additional ground motion simulations indicate that the PFC reduces peak displacements by 53% relative to conventional connections. As a ratcheting connector, the PFC accumulates crushing deformation on every nonlinear cycle, whether it is small or large in amplitude. Further analyses indicate that the cumulative deformation demand can be estimated at three times the peak connector deformation. With the PFC, few stocky fasteners may be a possible alternative to conventional timber connections requiring many slender fasteners for seismic applications.
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Data Availability Statement
Some or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request. These are results of the experiment and numerical simulations.
Acknowledgments
The authors would like to acknowledge Mark Byrami for providing valuable technical advice and assistance during experimental tests of the PFC. The University of Auckland is also gratefully acknowledged for financial support in the form of a Ph.D. scholarship and for facilitating the experimental work through the Structures Testing Laboratory.
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Published In
Journal of Structural Engineering
Volume 147 • Issue 5 • May 2021
Copyright
© 2021 American Society of Civil Engineers.
History
Received: Jul 9, 2020
Accepted: Dec 10, 2020
Published online: Feb 18, 2021
Published in print: May 1, 2021
Discussion open until: Jul 18, 2021
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