Old garage slab - 8" thick with steel beams cast in

[MidwestSE]

Hey everyone,

Has anybody seen a garage slab from the 1950's or so with steel beams fully embedded in the slab? See the attached picture.

The steel beams are 4' oc and span about 18' with a wood support post in the middle. It looks like there are 2#3 long bars in the slab running parallel to the beam and what looks like 7-wire strand at about 2' oc running perpendicular to the steel beams.

This has got to be an old way of doing a flat concrete arch floor system or something like that, but I'm having trouble finding any literature on it. It looks like a flat clay tile arch floor but made with concrete. Has anyone seen anything like this before and by chance know what it's called or have any literature on it?

Thanks!

 

[hokie66]

Probably a DIYer's way of building a slab, without engineering input.

 

[JStephen]

I remember seeing some old concrete in coastal fortifications where they apparently used railroad rails as part of the reinforcement. It wasn't the arrangement you show, just rails fully embedded in the concrete. I think that was built around 1900.
Meanwhile, I didn't find anything useful, but ran across this document which at least shows others thought of this as well:

https://bautechnikgeschichte.files.wordpress.com/2015/07/pelke.pdf

See Figure 4, for example.
I also find some examples of using beams with block infill, although generally the beams are concrete rather than steel.

 

[phamENG]

I run into weird elevated slab construction on mid-20th century houses in my area occasionally. One of my favorites used wire mesh as the form work stretched between two walls with the old concrete bags and other trash laid on top to keep the mud from falling through. Top of slab was nice and flat, the "form" had about a 6" bow in it over 12 feet.

In the post war boom of the late 40s to early 60s houses were going up like crazy with little to no oversight in most places. The contractors did what they thought might work - or at least what they thought they could get away with.

 

[HTURKAK]

The picture implies old type composite slab and called ( I BEAM ENCASED SLAB ).. I have an old book . ( The theory and Practice of Reinforced Concrete By DUNHAM , 1944 ). Below , a picture from the same book for this slab .

 

[kipfoot]

Tables for terra cotta flat arch systems show that they can hold a considerable load. Arching is probably the mechanism that's holding this slab in place, but I wouldn't want to rely on it...especially in its deteriorated condition. This floor must have been bouncy from the day the forms were removed, which explains why someone saw fit to stick some posts under the beams.