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Re: Tin Pan Joists

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David Handy wrote:

> I have looked at a building with stay in place tin pan floor joists that
> was building approx. 1930. I have the original drawings however the
> drawings state only 12" T.P.J. + 2" slab. No reinforcement for joists is
> given.

Can you give a description of this construction?  None of the old books I have
list any item with that name.

> I was called in to look at it because there is a 1" deflection in
> the floor over a span of 24' without any significant live loading. The
> condition of the floor slab is terrible and they want to level and smooth
> it with DuraCap a gypcrete product.
> They removed a 1" thick layer of what looked like solid asphalt or tar.
> This stuff weighed about 13 psf. Never seen that before. Went up in flames
> after 5 seconds. Does anybody know what this stuff is? There was linoleum
> over it.

The Structural Engineer's Handbook by Ketchum, (1926) lists tar concrete as part
a warehouse floor slab. It was composed of gravel, sand and tar heated, mixed and
tamped into place.

> As far as the structure goes I am at a bit of a loss as too how to check
> this floor and to why there is such a large built in deflection without any
> significant live loads...Apart from the old was built that way.
> I am planning to remove at bit of the pan at the quarter point and chip the
> concrete off to see what the bottom bars are. I will also inspect the
> concrete between the forms at the bottom of the ribs to check for any
> cracks. I can also do some inpact tests on the slab to check for concrete
> strengths although I don't know how accurate these will be on a 2" thick slab.
> Any thoughts or related experiences.
> David Handy, P.Eng.
> dhandy(--nospam--at)