existing steel/conrete building

[deereman]

I am working on a project that has steel I-beams that are encased with concrete carrying a concrete floor. From the underside of the floor there are 1'-0"x1'-0" terracotta tiles within the concrete slab. It looks like these were placed in the concrete form and the slab poured around them. In between these tiles there are areas of exposed rebar. This building is very old, does anyone know anything about this type of framing or know of any good reference material on it.

Anyone know of a good method to repair the exposed rebar?

 

[csd72]

It is called a pot and beam or a clay pot slab in the uk.

Basically works similar to modern ribbed forms but the clay pots act like void formers.

 

[DarthSoilsGuy]

I worked on one recently.

The Riddick Laboratory/engineering bldg building at NC State Campus in Raleigh North Carolina had both the terra-cota forming and the concrete encased steel structure. i couldn't find any information on it with a search, but i'm sure there must be something since it was very much in their own backyard. the renovation started 3 years ago and was a full gutting structural/architectural renovation of the building.

 

[JedClampett]

Do any of the systems in this article match what you're seeing?

http://www.structuremag.org/Archives/2007-12/C-EngineersNotebook-Stuart-Dec07.pdf

 

[JKW05]

Check out page 266-268 of 1923 Carnegie Pocket Companion on sliderule's website (under misc. publications and documents). Is that what you have?

http://www.slideruleera.net/

 

[deereman]

No, neither of those articles is what I have. Mine structure is not arched.

 

[concretemasonry]

It sounds like a typical "floor filler" slab system that is/was used in Europe. The hollow clay tile (or concrete block, concrete/wood fiber, AAC, etc.) are used to decrease the weight and provide a flat ceiling for finishing. They are still used in many reisdential projects and there are EU standards for the materials for the fillers. Usually these are just one way systems, but you seem to be describing a two way system.

I am not an expert on the repairs, but the cleaning and developing the strength of the rebars will be a big challenge.

 

[DarthSoilsGuy]

deereman,
those references don't match what i saw either at the NC State Civil Egr school.

 

[jike]

The Carnegie handbook has flat terra cotta arches. They don't look like arches.

 

[JedClampett]

Actually the article from Structure Magazine from my earlier post also has flat clay tiles in Figures 2 and 3.

 

[csd72]

deereman,

It is a pretty simple concept. The clay tiles dont do much apart from holding up the concrete between the beams.

The concrete between the tiles act as simple T beams and should be analysed as such.

Beware that the shear capacity is very low for these slabs.

 

[lexim]

Hello deerman,

From all the above responses and your description of the floor, I would suppose you are referring to a ribbed slab or a waffle (2-way ribbed slab). If so, csd72 already told you the regular design considerations just as a T-beam. the shear at the ends need to be checked and usually the ends require some thickening to take care of some rotation and moments.

As per the repairs, ithe method to use will depend on the necessity of repair after you have carried out your inspection and investigations. Corrosion resulting from cover inadequacy is a major consideration for durability and strength but you may be able to addd new rebars to substitute for these effect.

Consideration of use of stirrups, or rings are optional but usually depend on the shear capacity of the concrete.

Shotcrete concrete is best used in repairs.
Let us have a few of your concerns and we can give our comments.

Thanks