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Re: steel decking

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steel decking working as composite section for vertical
loads and as a diaphragm for lateral loads
so my worry is
1- for vertical loading  there is more concrete in buckling area
and it might be close to yielding or the spot weld will fail and full
yes it is roof but you don't  know what will happen

and yes I indicate the direction of span by arrow but I guess the
contractor has no experience with steel decking

2- if the weld fail there will be no diaphragm in this area
it will go loose if earthquake happen although there is
welded wire mesh  in the concrete but that only
temperature steel

thanks for everyone giving his opinion that was
a lot of support

D.A. P.E.

-----Original Message-----
From: Juan C. Gray <juangray(--nospam--at)>
To: seaoc(--nospam--at) <seaoc(--nospam--at)>
Date: Monday, October 27, 1997 11:23 AM
Subject: Re: steel decking

>I disagree with you; steel deck works both as formwork, and as
>reinforcement for permanent loads.
>Juan C. Gray
>Bill Allen wrote:
>> Although the metal deck usually only works as a concrete form and
>> does not provide structural capacities once the concrete has achieved
>> strength, there are several other concerns. First, you should verify the
>> above assumption with the metal deck manufacturer of either the metal
>> you specified or the deck the contractor used. If the deck manufacturer
>> confirmed the above assumption, the other worries are concerned with
>> on the supporting members such as:
>> 1.    Since the deck is now being supported by members orthogonal to the
>> original design, are they capable of supporting the design loads? Do the
>> load paths still work?
>> 2.    Since the deck has deformed, there probably is more concrete than
>> the original design. This additional superimposed dead load is (probably)
>> not acceptable with regards to the strength of the supporting members.
>> I would have a tendency to instruct the contractor to rip out the deck
>> concrete and do it right, report to the owner that the contractor doesn't
>> know what he is doing and report the contractor to the state board for
>> incompetence.
>> Other than that, it appears O.K. to me :o).
>> Regards,
>> Bill Allen
>> (the cynic)
>> -----Original Message-----
>> From: Dave Anderson <dnae(--nospam--at)>
>> To: seaoc <seaoc(--nospam--at)>
>> Date: Sunday, October 26, 1997 12:10 PM
>> Subject: steel decking
>> >Hi
>> >I need some opinion regard field matter
>> >
>> >I specified 20 GA steel decking to span 8 ft  with 4 1/2 " light weight
>> >concrete the contractor change the direction of steel decking without
>> >consulting me and  span it 12 feet without shoring one area deflect and
>> >buckled out
>> >about 8x12 feet  so he called me to fixed
>> >what you think
>> >1- adding a beam under the deflected area
>> >     which is deformed,but it is very strong
>> >2- remove the deformed (roof) decking and replaced
>> >     with new one and pour new concrete
>> >
>> >thanks in advance
>> >
>> >Dave A. P.E.
>> >
>> >
>> >
>> >