OWSJ / concrete precast composite system identification

[OldBldgGuy]

I saw a different floor and roof system last week & I can't find the manufacturer. It's a building in southern Ontario (Salvation Army church), built in the early 1960s that looks essentially like a Hambro composite system: OWSJ and concrete composite, except they were precast in 4' wide planks, not cast in place. The joists are 32' span at 2' centres, 12" from each edge of the planks. The floor planks are 2 1/2" thick concrete and there is 15" of exposed joist depth. There are steel tabs visible in the joints between the slabs that apparently were welded together for load transfer. The new owners want to change some things & I'm trying to find a quick way to get the original capacity. Anyone seen these before and know of any design tables?

 

[JAE]

No idea - can you get a joist tag off one of the joists? Might have a manufacturer's name on it.


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[dik]

Could it be a Hambro system with a site or plant precast 2' wide topping system to act as a form for additional composite concrete topping over?

Not necessarily a system, but, an innovation by a contractor? It would provide lateral support for the OWSJ as well as a form for the concrete topping.
Dik

 

[OldBldgGuy]

I didn't see any tags, there was a (presumably) job number written in magic marker on one end of the joists. There is no topping on the floor other than a skim coat to fill the joints; there are holes for pipes and ducts so it's easy to see the section. They were clearly cast upside down, the concrete was poured in 4' wide forms and 2 joists were set into each plank. There are float marks on the now underside and you can see where the joists were pressed into the concrete. The bottom chord is a 3 1/2" wide cold-formed W (rather rounded) and the webs are 1/2" rod.
Possibly Hambro done by an innovative contractor but was Hambro around in 1962?

 

[EngineeringEric]

I've got to say, that is kind of cool looking!

Check out:

http://www.aerialprecastconcrete.com/engineering/

"Produced at our facility, Aerial™ floor units are fabricated in widths of up to 8 feet and lengths of up to 40 feet; are typically composed of 17″ deep steel bar joists embedded into 3″ concrete panels (depth of joists may vary), at 5,000psi and poured around embedded 6/6, i.e. 6″x6″ welded wire mesh, into slightly cambered molds. They are then transported to the site and placed at 3″ on top of the tie, bond or steel beams of the structure; precisely adjusted and welded together at the ends. The remaining joints are then grouted."

 

[dik]

The old DB Joist catalogues used to have duct sizes and opening information.

 

[OldBldgGuy]

Aerial looks very much like this system, but their website says "producing quality precast in Florida for over 20 years" which puts them 30 years too late and 1800 km too far south to have done this building. Thanks for the link.