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Re: Metal Deck

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Dear Jordan, Bob, Gary,
                                           Thanks for your reply. Sorry, I did not provide you sufficient information.
This deck is considered as a form deck ( permanent shutter), depth of the deck is only 49 mm and overall depth including concrete is 100 mm. It is zinc coated and used for an office floor construction. The section modulus of the deck is enought to carry the load during casting even if I reverse the profile.
According to BS 5950 if the profile thickness is less than 0.75 mm the deck should be considered used only for the purpose of a form.
Another clause of this code says minimum size of aggregate used in concrete should be less than 1/3rd of the rib bottom dimension. If I use the profile as per contractors proposal aggregate size should be less than 10/3 = 3.33 mm, which is not advisable.( Rib size 10 mm at bottom 40 mm at top and at 160 mm c/c )
Could you please let me know the requirements as per American codes.
Kind regards,
Resident Engineer,
SSH International consultants

On 8/28/06, Jordan Truesdell, PE <seaint1(--nospam--at)> wrote:
I'm not usually one for semantics, but you may want to amend that. The section modulus will be identical for a section symmetrical about the y axis when rotated 180 degrees about the x axis. The compression and tension fiber will be flipped, however this is a steel fabrication and the properties are (nominally) non-isotropic. There may be stability issues, including buckling/crippling, which may vary with orientation but the minimum section modulus (S) will remain the same numerical value, as both the moment of inertia and the outer fiber distance are constants.

Sorry to be pedantic this Monday morning, but the whole concept of "bending" stress has rubbed me the wrong way since entering the building industry. It is a useful concept and makes for computational efficiency but it is an artifact of dealing with materials which are not isotropic-homogeneous and wanting to treat them without computational gymnastics.

Most of us knew exactly what you meant, but there may be some on this list who would take your parenthetical to equate bending strength with section modulus in all cases.
PS - Feel free to call me out on my next's just a matter time ;-)

Garner, Robert wrote:

Before you reverse the profile, please consider that the bending strength (section modulus) of the deck will be different depending on which side of the deck is up.


Bob Garner, S.E.


From: Gary Loomis [ mailto:gloomis(--nospam--at)]
Sent: Monday, August 28, 2006 6:33 AM
To: seaint(--nospam--at)
Subject: RE: Metal Deck


Please provide additional information.  Is this a roof deck, composite metal, or form deck?  What is the depth of the deck?  What are the section properties required?  We typically specify minimum section properties and steel strength requirements.  Is the deck galvanized or painted?


-----Original Message-----
From: Ravinath M. [ mailto:ravinath27(--nospam--at)]
Sent: Monday, August 28, 2006 3:31 AM
To: seaint(--nospam--at)
Subject: Metal Deck


Hi All,

            Can anybody give me the requirements of metal deck profile.

I am currently checking the design submitted by a contractor for an office floor. They proposed a metal deck of 0.64 mm thickness, ribs with the following dimensions.

10mm at bottom, 40 mm at top at 165 mm c/c spacings.

Is there any criteria for selection of profile dimensions?

According to the dimension of the profile proposed bearing width on support will be just 10mm. I suggested to reverse the profile to have more bearing on the support.

Kindly give me your opinion on this.




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