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Re: Cost Analysis

[Subject Prev][Subject Next][Thread Prev][Thread Next] Jason,

I believe spacing the wide flange girders @ 6'-0" to 8'-0" is greatly under
utilizing the system - materials.  We engineer a lot of buildings of this
type of construction.  Ideally, you want a 30'-0 x 30'-0 column grid (28'-0
to 32'-0 spacing range).  Space W24 girders @ 30''-0 o.c. then uniformly
space the beams, W14 or W16's, @ 10'-0 between the W24 girders.  Use 18ga -
W3 deck with 2.5" of lightweight concrete fill over the top of the flutes.  
Total thickness of the deck and fill is 5.5".  This also provides a 1 hour
fire-resistive assembly.  The deck will span 10'-0 unshored.  Anything much
less than this span is inefficient for the deck.  We also typically design
for 52 to 55 psf dead load + 20 psf partition load + 80 psf live load.  This
system works quite well.   The column size is usually a W10, however, if you
are crunched for space, you can make W8's work (assuming this is only a two
story structure).   

I am also an engineer who "dislikes" open web joist systems so, admittedly, I
am  quite biased.  Please let me know the outcome of your cost analysis.

Greg Showerman, S.E.