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Re: Light Gauge Steel - Full-Compliance Design

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I have been designing several plywood deck diaphragms on Light Gauge Steel
lately, without any problem with the City of El Segundo. In my case the
diaphragms are flexible and I am using ICBO #4144 which also gives you
criteria to determine the corresponding deflection.

Hope this helps

Julio M. Guerra S.E


                    "Dennis S.                                                                                  
                    Wish"                To:     "Lynn Howard" <lhoward(--nospam--at)>                             
                    <dennis.wish@        cc:     "SEAINT Listservice" <seaint(--nospam--at)>                       
          >             Subject:     Re: Light Gauge Steel - Full-Compliance Design            
                    10:40 AM                                                                                    
                    respond to                                                                                  

I'm in digest mode which makes quick responses difficult. I wanted to thank
you for the advice. I guess what I wanted to know was how to address the
issues of diaphragm deflection which are calculated for blocked wood
diaphragms. How do we treat a light-gauge steel diaphragm with plywood when
concrete is not being used. In my case, the Architect is trying to make a
statement by designing a conventional home using only cold-form steel
is not exposed). The energy restrictions just barely bring this up to
minimum compliance which should - in my opinion, defeats the advantages of
steel compared to wood in a desert climate.
The Architect also argues that wood warps, twists and in nominal sizes is
not desirable to him. His bias comes from more than 30 years designing
(light-gauge) industrial and commercial structures.

I don't see the advantage when material and labor cost is higher (the
builder who will do this project has little experience in light-gauge

Mike Krakower called me in the middle of writing you, to offer me his
opinions. As you indicated, Mike feels it is "doable" with a pan deck and
lightweight concrete and rigid braced frames (verses vertical plywood
shear), but when trying to design it to full compliance, there is not much
known about the performance of the horizontal diaphragms with plywood
sheathing to apply to the rigid analysis. Mike indicated some work coming
out of testing at Irvine that may provide additional information (to be
released as a COLA report). I'll check into this further.

Thanks again for taking the time to respond - I do appreciate it.

Dennis S. Wish, PE
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