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Re: RE: LRFD, ASD, and USD

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The articles Mr. John Jones is referring to are very helpful.  In my question
on DL Deflection, someone gave them to me as reference.  You can download the
articles, in a very slick format by the way, through their website at
http:/ You will need to sign on (free) in order to gain
access to their library/archive.  Then, do a search for "elevated concrete

>>> <seaint-return(--nospam--at)> 07/31/98 09:57AM >>>
A few days ago I mentioned an article in Concrete Construction that
addressed the composite issue.  Here is a summary of what the article was

A 30'-0"x30'-0" bay was designed with 100 psf LL and beams at 10'-0" o.c.

Using ASD & 36ksi the beams were W18x40's and girders W27x84.->6.8psf steel
Using ASD & 50ksi the beams were W16x31's and girders W24x62.->5.2psf steel
Using LRFD& 50ksi the beams were W16x26's and girders W24x55.->4.4psf steel

Based on this the percentage savings that were mentioned earlier in the
thread sound about right.

Here are the deflections for the various designs.

Summary for ASD and 36ksi
                Uniform Load | Ponded
Girder Defl.       0.31         0.34
Beam Defl.         0.57         0.63
Deck Defl.         0.20         0.22
Total              1.08         1.29

Summary for ASD and 50ksi
                Uniform Load | Ponded
Girder Defl.       0.57         0.68
Beam Defl.         0.94         1.12
Deck Defl.         0.20         0.24
Total              1.71         2.04

Summary for LRFD and 50ksi
                Uniform Load | Ponded
Girder Defl.       0.65         0.80
Beam Defl.         1.16         1.42
Deck Defl.         0.20         0.25
Total              2.01         2.57

Camber was discussed in the article but vibration was not.
The article later discusses ways to build the slab on trampoline floors
and recommendations on maximum deflections.

I don't know if the Aberdeen Group has a website for the download of such
things but it was a pretty good article.

John Jones