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Re: 1-3/4" roof slab

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Well, not really, but I'll take a stab at anwering.

You didn't say how the slab is being constructed.  Is the expanded metal laid on the bottom of
the form, then concrete placed, then the plaster added after stripping the forms?  Or, is the
slab formed, then the metal attached to the bottom and then covered with the plaster?

What is suporting the slab?  Is it supported on all 4 sides?  Is the slab actually a one way
slab, spanning the short (or long - I hope not) direction?

If the metal is placed on the bottom of the form, and then the concrete placed, the plaster is
nothing more than dead load which provides protection for the metal against corrosion.

If the metal is attached to the bottom of the pre-cast slab, then the bond between the metal and
concrete has to be sufficient to achieve composite action between the concrete and the metal.
Otherwise, you don't have reinforced concrete, you have metal sandwiched between two concrete
slabs.  Again, the plaster is only DL providing protection for the metal.

Lew Midlam
=========================

Alex C. Nacionales wrote:

> Dear  John,
>
>    This is a one way slab exterior stair roof..
> Short span is 1.20 M, Long span  is 6.3 M
> Loading is 1.44Kpa(30 psf.). Fy = 227Mpa(33000
> psi).  Fc' =(27.5Mpa) 4000 psi.
> Reinforcement: short span= 6 mm @ .10 , long
> span = 6mm @ .20.
>
> I assumed the 1" plaster to part of the total
> thickness because of the expanded metal
> additional reinforcement. That makes total
> thickness of  2-3/4".
>
> I am sure the above data is complete for your
> information.
> Thank you for your interest.
>
> Sincerely Your,
>
> ALEX C. NACIONALES, C.E.
> Iloilo City, Philippines
>
> John F. Jones wrote:
>
> > Can you provide some more information?  I.e
> > what is the span, loading, ect.
> > A 1-3/4" slab spanning any distance sounds
> > kind of thin?!?!
> >
> > John F. Jones
> > Winzler & Kelly Consulting Engineers
> > Guam
> >
> > At 05:14 AM 6/12/98 +0800, you wrote:
> > >Hello guys,
> > >
> > >I designed a 1-3/4  RC roof slab w/ 1" cement
> >
> > >plaster with expanded metal wire mesh
> > >reinforcement to minimize temperature cracks.
> > I
> > >also plan to use fly ash on the cement
> > plaster.
> > >This is for my school building project.
> > >
> > >I need your comments regarding this. Any body
> >
> > >with experience on this type of roof?
> > >
> > >Thanks in advance.
> > >
> > >Alex C. Nacionales, C.E.
> > >Iloilo City, Philippines
> > >
> > >
> > >
> > >
> > >
> > >
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