Instructural engineering,aWarren trussorequilateral truss[1]is a type oftrussemploying a weight-saving design based uponequilateral triangles.It is named after the British engineerJames Warren,who patented it in 1848.
Origins
editIt was patented in 1848 by its designersJames Warrenand Willoughby Theobald Monzani.[citation needed]
Truss
editThe Warren truss consists of longitudinal members joined only by angled cross-members, forming alternately invertedEquilateral triangle-shaped spaces along its length. This gives a pure truss: each individualstrut,beam,ortieis only subject to tension or compression forces, there are no bending or torsional forces on them.
Loads on the diagonals alternate between compression and tension (approaching the centre), with no vertical elements, while elements near the centre must support both tension and compression in response to live loads. This configuration combines strength with economy of materials and can therefore be relatively light. The girders being of equal length, it is ideal for use in prefabricated modular bridges.
It is an improvement over theNeville trussin which the elements formisosceles triangles.[2]
A variant of the Warren truss has additional vertical members within the triangles.[1]These are used when the lengths of the upper horizontal members would otherwise become so long as to present a risk ofbuckling[i]These verticals do not carry a large proportion of the truss loads; they act mostly to stabilise the horizontal members against breaking down.
Bridges
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Architecture
editThe Warren truss is a prominent structural feature in hundreds of hastily constructed aircraft hangars in WW2. In the early parts of the war, the British and Canadian government formed an agreement known as theBritish Commonwealth Air Training Planwhich used newly constructed airbases in Canada to train aircrew needed to sustain emerging air forces. Hundreds of airfields, aprons, taxiways and ground installations were constructed all across Canada. Two characteristic features were a triangle runway layout and hangars built from virgin British Columbia timbers with Warren truss configuration roofs.[5][6]Many still remain in service.
Aircraft
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Warren truss construction has also been used inairframedesign and construction, for substantial numbers of aircraft designs.
An early use was for the interplane wing struts on some biplanes. The Italian World War IAnsaldo SVAseries of fast reconnaissance biplanes were among the fastest aircraft of their era, while theHandley Page H.P.42was a successfulairlinerof the late 1920s and theFiat CR.42 FalcoFalcofighter remained in service until World War II.
The Warren truss is also sometimes used forfuselageframes, such as in thePiper J-3 CubandHawker Hurricane.
Notes
editExplanatory notes
edit- ^Column theoryshows that the risk of buckling increases with length, not merely compressive load.
Citations
edit- ^abFrank Griggs, Jr. (July 2015)."The Warren Truss".Structure.
- ^"Warren Truss".Garrett's Bridges.
- ^Jones, Stephen K. (2009).Brunel in South Wales.Vol. III:Links with Leviathans.Stroud: The History Press. pp. 20–21.ISBN9780752449128.
- ^de Maré, Eric (1975) [1954].Bridges of Britain.Batsford. pp. 86–87.ISBN0-7134-2925-9.
- ^"Hangar #14".HistoricPlaces.ca.Retrieved26 December2019.
- ^Rkelland (10 February 2016)."Hangar 14 and the British Commonwealth Air Training Plan".Retrieved26 December2019.
External links
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Media related toWarren trussat Wikimedia Commons
