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Expansion Joints for Exposed Structural Steel

Expansion Joints for Exposed Structural Steel

Expansion Joints for Exposed Structural Steel

(OP)
Does anyone know of a technical document and/or spec. that outlines & discusses expansion joints for exposed structural steel?

I've already read thread594-20505 from this site, however, this thread discusses BUILDING expansion joints and makes no reference to long, non-building steel structures in direct exposure to the sun and the temprature changes.

For example,

I am designing a structural steel pipe trestle that will be on the roof of an automotive plant. The trestle has overall dimensions as high as 900ft. Expansion joints will be needed and I am seeking supportive technical/spec documentation simular to the one mentioned in thread594-20505 but in regards to exp. joints for whether exposed steel.

Any help would be most appreciated.
  

RE: Expansion Joints for Exposed Structural Steel

Steel does not generally need expansion joints due to the over size holes at connections and the ductility/deformability of steel.  If continuous members or welded members of long length are used, then slotted support connections are sometimes provided.  The railroads has made continuous rails of miles in length held in alignment with spikes into wood ties.  If the long dimension is restrained against expansion/contraction, then added compressive/tensile stresses will occur from the restraint, but usually a design can be made to tolerate the addition of axial temperature stress.

RE: Expansion Joints for Exposed Structural Steel

For steel exposed to the elements, I prefer to break it into 100' sections without taking additional measures for thermal expansion and beyond that, I don't like to go beyond 200' for exterior stuff... for heated buildings I don't like to go beyone 300' (arbtrary dimensions).

For shelf angles, I don't like to go beyond 20' or 30' realizing that temperatures can span from -40C to +30C.

Was involved with a project near Bancroft, Ont where they had 900' without control joints.  My memo recommended against the manner of support... no control joints and a diagonal brace to grade at the one end.  Last I heard, they were talking to lawyers.

Dik

RE: Expansion Joints for Exposed Structural Steel

Perhaps some kind of variation on the theme of bridge expansion joint?  

Hg

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RE: Expansion Joints for Exposed Structural Steel

The roof manufacturers will specify a maximum distance to expansion joints in metal roofing. This may act as a guide for you, although fixings on these will generally allow abit more movement than structural steel.

If you are really worried, you may be able to measure temperature effects with your analysis package (including additional stresses in supporting members)

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