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Re: Sag-rod effectiveness?

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> From: "Sunil Thengale" <Sunil_Thengale(--nospam--at)>

> For the cold formed purlins, I have seen in some projects that they have
> used sag-rods which are prepared from slit coil waste-1.5mm thick and
> bent to get a circular shape of 15-16mm dia, the joint being open say
> 2-3mm . The ends of these sag -rods have the clips (as in umbrella) to
> lock these rods in purlins. How are these sag-rods compared to normal
> rods, angles etc?.  Are they really effective? Any views will be highly
> appreciated.

I would expect your R&D group to have recommendations on this member.

The member is probably relatively strong in the typical 1200 to 1500 mm
lengths that are common for sag angles. Whether the assembly responds as
desired is more complex to assess. Due to the open "slit" along the
length, it will not respond as well as a closed tube and may be
sensitive to handling damage.

In North America, it is common to use cold formed angle/channel or
simple straps (which I dislike intensely) as "sag" restraints - an
egregious misnomer. I would expect an open tube to be capable of
responding as well as other sections in service. It is possible to do
the analysis and essential to do the testing. 

Not sure what you are describing as an "umbrella" clip.


R. Paul Ransom, P. Eng.
Burlington, Ontario, Canada
<mailto:ado26(--nospam--at)> <>

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