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Re: Databases for lt gage steel[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: seaint(--nospam--at)seaint.org
- Subject: Re: Databases for lt gage steel
- From: Phil Hodge <phil(--nospam--at)joistdesign.com>
- Date: Thu, 23 Dec 1999 00:02:35 -0500
I don't know about light gage, but for bar joists you are absolutely correct. K-series and LH-series joists, as well as joist-girders, are custom designed for each job. And if the job is big enough some joist fabricators will commission a special rolling a few thousands thicker or thinner to use the steel as efficiently as possible. Don't bother wasting your money on FloorVib2 if all you want is the joist properties, as those used in the program are approximate only. They can't be exact because each joist is custom designed for each job, as I said before. If you purchase a particular joist today, and the same joist tomorrow, from the same manufacturer, there is no guarantee they will be the same. And from different manufacturers, or from the same company but made in different plants, there is practically a guarantee that they will be different. They will all meet whatever properties you specified, but anything you didn't specify may be different. So if you need chord width for stud attachment - specify it. If you need minimum (or maximum) moment of inertia - specify it. If you need a certain web opening or panel spacing for your mechanicals - specify it. If you need minimum angle thickness for longevity in a corrosive environment - specify it. And of course if you need a certain strength or stiffness - specify it. I was on a job recently that had over 5,000 joists and 600 joist-girders. All from the same manufacturer. They all had 4' panels EXCEPT FOR 3 BAYS! The mechanical contractor hadn't yet seen this yet. His first reaction when I pointed it out was to cut out any webs that interfered with his duct runs. If the EOR had specified that all joist panels must line up, there would not have been a problem. But all he specified was strength, so that's all he got. Phil William Keil wrote: > Does anybody know why the properties of joists are not published? My theory > is that each joist is rolled specifically for each loading detailed on the > drawings and if they can roll the angles 1/32" thinner or shorten the angle > legs by a 1/4" and still meet your loading/span criteria, the manufacturer > will do it to save material and increase profits. > > I recall seeing K-joist properties being included in the FloorVib2 program > offered by STRUCTURAL ENGINEERS INC., 537 Wisteria Drive, Radford, VA > 24141, 540.731.3330, 540.639.0713 FAX. Cost is $250 plus $10 s/h plus VA > sales tax if you are a resident. If I do more work with composite joists I > would invest in this but right now the price is too steep just to get joist > properties. Because once you have the joist properties, you will need the > joist girder properties and you are back where you started ... looking for > unpublished data. Good luck!
- RE: Databases for lt gage steel
- From: William Keil
- RE: Databases for lt gage steel
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