The structural response and progressive failure of batten to rafter connections under wind loads

Parackal, Korah Ipeson (2018) The structural response and progressive failure of batten to rafter connections under wind loads. PhD thesis, James Cook University.

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View at Publisher Website: https://doi.org/10.25903/5e44a8f18ebdf
 
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Abstract

Batten to rafter connections in light framed timber housing are vulnerable to wind loading and failures of these connections are one of the more common failure modes seen in post windstorm damage surveys. Such failures often occur in a progressive or cascading manner resulting in the loss of a large section of the building envelope. These progressive failures of batten to rafter connections are a complex process influenced by the pressure fluctuations on the roof surface, the response of individual connections and the behaviour of the structural system as a whole.

This study presents a method of examining load redistribution and progressive failure behaviour of batten to rafter connections in light framed structures. Nonlinear time history analysis was performed using a finite element model using fluctuating pressures determined from a wind tunnel study and connection properties determined from laboratory testing of connections under dynamic loads.

Flow separation and building-induced turbulence cause intermittent 'peak-events' where negative pressures on the roof surface are especially high. These 'peak-events' can move across the roof causing high loads occurring at different connections with slight lead or lag times. Damage to connections occur during the 'peak events' as nails are incrementally withdrawn. Loads are redistributed and load paths change during nail slips, causing damage to spread from an initial location. Load redistribution continues until a few connections fail completely, upon which a cascading failure occurs where almost all connections on the roof fail in rapid succession.

As an application of this research, the analyses performed were used to assess the fragility of batten-rafter failures, and the most vulnerable parts of the roof identified. Cost effective retrofitting measures can be justified and designed with this information.

Item ID: 62277
Item Type: Thesis (PhD)
Keywords: wind tunnel study, light framed structures, low-rise buildings, correlation of loads, progressive failures, wind loads, batten to rafter, wind engineering
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Copyright Information: Copyright © 2018 Korah Ipeson Parackal.
Additional Information:

For this thesis, Korah Ipeson Parackal received the Dean's Award for Excellence 2020, which recognises excellence in Higher Degree by Research and recipients of this award are commended by independent expert examiners as having made a substantial contribution to their field of research.

One publication arising from this thesis is stored in ResearchOnline@JCU, at the time of processing. Please see the Related URLs field. The publication is:

Parackal, Korah, Ginger, John, and Henderson, David J. (2018) Wind load fluctuations on roof batten to rafter/truss connections. Journal of Wind Engineering and Industrial Aerodynamics, 175. pp. 193-201.

Date Deposited: 13 Feb 2020 02:14
FoR Codes: 09 ENGINEERING > 0905 Civil Engineering > 090506 Structural Engineering @ 100%
SEO Codes: 87 CONSTRUCTION > 8702 Construction Design > 870204 Residential Construction Design @ 100%
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