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LGSI

06/19/2012 4:06 PM

Any LGSI guys around? What exactly is the difference between Continuously Braced, Thru-Fastened, and Laterally Braced?

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#1

Re: LGSI

06/20/2012 2:19 AM

Throw us a bone!!!

LGSI=Light gauge steel or some such?

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#5
In reply to #1

Re: LGSI

06/20/2012 7:38 AM

Correct, Light Gauge Steel Institute.

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#2

Re: LGSI

06/20/2012 4:01 AM
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#3

Re: LGSI

06/20/2012 4:08 AM

I just saw a metal building going up this weekend at a buddy's place. The installers could not decipher all the acronyms on the prints and web searches on my iPhone were no help either.

LGSI is now abandoned by Loseke, so all you can do is call Central States http://www.centralstatesmfg.com/

It was Light Gauge Steel Institute at one time, right? With specs for fastener and girt spacings on panels that were Continuously Braced vs Thru-Fastened vs Laterally Braced? And all kinds of data for wall heights and roof pitches and you could plug into AutoCad and all kinda everything. Doesn't mean squat if you don't have the secret spy decoder ring.

Best guess is try Central States or one of your local "metal mart" supplies and see if they will translate the LGSI specs into pen and paper english for you.

Or, hope another CR4 member has a better memory than the two guys I met this past weekend. Their mantra was "if there's still screws in the box, it's probably not as tight as it could be". Glad that's not my barn.

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#6
In reply to #3

Re: LGSI

06/20/2012 8:13 AM

I wonder why Loseke abandoned LGSI.

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#4

Re: LGSI

06/20/2012 7:09 AM

If you are referring to "Light-Gage Steel" framing members, then you want to obtain a copy of the American Iron and Steel Institute (AISI) "Specification for the Design of Cold-Formed Steel Structural Members".

Continuously braced: All parallel framing members in a given plane (like roof trusses TC & BC, roof rafters, floor joists, and wall studs) have a piece of lateral bridging attached to each and every members for the entire framing plane.

Through-Fastened: Typically a threaded through rod, etc., passes through the web section of a framing member to hold it in it's position.

Laterally Braced: This is nearly the same as "Continuously Braced", but the lateral bracing pieces (ie, bridging) are attached to the compression flanges of the framing member.

I'm sure there are better definitions available out there somewhere, but these are off the top of my noggin' so early in the morning with only a mug of Java under my belt!

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#7
In reply to #4

Re: LGSI

06/20/2012 9:15 AM

Good morning CaptMoosie,

I am using Loseke's LGSI recomendations, which I assumed were based on the AISI's Specs, since the AISI's was started in the 1920's.

For an agricultural building, say you have 25' long roof purlins 5' oc with paneling screwed to the top flange, with nothing attached to the bottom flange between rafters. This would not be Continuously Braced, agreed?

If the purlins are attached with an angle screwed to the rafter and thru the purlin web, it becomes Thru-Fastened?

If a small straight angle is attached from purlin bottom flange to purlin bottom flange, within the LGSI oc limitations, it is now considered Laterally Braced, or does the brace have to go from the bottom flange of one purlin to the top flange of the adjacent purlin?

After 1-1/2 mugs of Java, YMMV.

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#8
In reply to #7

Re: LGSI

06/20/2012 9:57 AM

Sorry, I'm not familiar w/ the LGSI specs or standards and will have to do further research......I only follow AISI standards. A whole lot depends on the fastener spacings and the purlin shape, be it a Z, channel or C-stud type.

When all else fails, follow the manufacturer's written installation instructions. Not all manufactured light gage steel sections are made the same same nor load tested equally.

I'll have to get back to you regarding your specific questions, but it would help to know the particulars, especially the type, size and spacing of the fasteners and the type and section of the rood purlins. Was the roof framing designed by a registered PE, specifically a SE?

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