Lateral Load Path and Capacity of Exterior Decks
Publication: Practice Periodical on Structural Design and Construction
Volume 19, Issue 4
Abstract
Exterior decks must be designed to resist all applicable load cases. Vertical (gravity) loads are well defined, but less is known about designing decks for lateral loading. The focus of this study was to better understand the ultimate strength and load paths of two common deck constructions subjected to monotonic lateral loading. A portion of a conventional light-frame wood-floor diaphragm was built, to which the decks were attached. One deck was constructed with a lateral hold-down tension connector and the other deck had no hold-down tension connector. The lateral resistance and load path of each deck were investigated by applying a monotonic force through the centroid of the deck surface. The ledger board was connected to the house rim board with lag screws. Forces in each lag screw and hold-down connecting the deck to the diaphragm were recorded. Preliminary tests revealed a weakness in the deck joist–to–deck ledger connection; this was resolved by using joist hangers that featured a perpendicular fastener attachment and manufacturer-approved screws. With this weak link reinforced, the connection between the deck ledger and the house rim board was investigated and it was found that it remained structurally intact with no observed damage up to a maximum load of approximately 31 kN for both deck constructions (with and without the tension hold-down connector). The main failure mechanism was splitting of the top edges of the joists (tension perpendicular to grain) caused by a resisting force couple created by pairs of deck board screws fastening the deck boards to the joists. In both cases and as expected, the lags screws near the end of the ledger experienced the greatest tensile forces.
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Acknowledgments
Donations of construction materials from Simpson Strong-Tie and Trex Company are gratefully acknowledged.
References
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Information & Authors
Information
Published In
Practice Periodical on Structural Design and Construction
Volume 19 • Issue 4 • November 2014
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Apr 30, 2013
Accepted: Sep 24, 2013
Published online: Feb 27, 2014
Discussion open until: Jul 27, 2014
Published in print: Nov 1, 2014
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