Mechanical and artificial improvement of nailplate connected timber truss joints

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Author(s)
Mainey, AJ
Gilbert, BP
Bailleres, H
Gunalan, S
Smith, M
Year published
2016
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Show full item recordAbstract
Timber trusses are widely used in the housing market, which members are often connected by nailplates.
However, the use of this type of connection is restricted to environments where the moisture content variation is
somewhat limited (such as the building envelope). This is due to the nailplates being driven out from the timber as a
result of the mechano sorptive withdrawal effect, commonly referred to as “backout”. Recently, this backout was
observed in more controlled environments thus prompting a linked project between industry and Griffith University to
investigate solutions to increase the tooth withdrawal resistance ...
View more >Timber trusses are widely used in the housing market, which members are often connected by nailplates. However, the use of this type of connection is restricted to environments where the moisture content variation is somewhat limited (such as the building envelope). This is due to the nailplates being driven out from the timber as a result of the mechano sorptive withdrawal effect, commonly referred to as “backout”. Recently, this backout was observed in more controlled environments thus prompting a linked project between industry and Griffith University to investigate solutions to increase the tooth withdrawal resistance under common design loading conditions and cyclic moisture contents. Two different design approaches are taken: (i) by mechanical means through a redesigned tooth profile allowing the nails to resist the pull out force by both friction and mechanical action and (ii) through application of an adhesive to two different tooth profiles. The new designs were experimentally assessed using single nails with respect to their quasi-static withdrawal resistance and their ability to resist the backout through accelerated moisture cycling. Results showed that the proposed mechanical designs have comparable performance with currently used nails, while the application of adhesive significantly decreased the backout.
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View more >Timber trusses are widely used in the housing market, which members are often connected by nailplates. However, the use of this type of connection is restricted to environments where the moisture content variation is somewhat limited (such as the building envelope). This is due to the nailplates being driven out from the timber as a result of the mechano sorptive withdrawal effect, commonly referred to as “backout”. Recently, this backout was observed in more controlled environments thus prompting a linked project between industry and Griffith University to investigate solutions to increase the tooth withdrawal resistance under common design loading conditions and cyclic moisture contents. Two different design approaches are taken: (i) by mechanical means through a redesigned tooth profile allowing the nails to resist the pull out force by both friction and mechanical action and (ii) through application of an adhesive to two different tooth profiles. The new designs were experimentally assessed using single nails with respect to their quasi-static withdrawal resistance and their ability to resist the backout through accelerated moisture cycling. Results showed that the proposed mechanical designs have comparable performance with currently used nails, while the application of adhesive significantly decreased the backout.
View less >
Conference Title
WCTE 2016 - World Conference on Timber Engineering
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Copyright Statement
© The Author[s] 2016. The attached file is reproduced here in accordance with the copyright policy of the publisher. For information about this conference please refer to the conference’s website or contact the author[s].
Subject
Structural engineering