Reinforced Concrete Gypsum Diaphgram Shear 1

[microbug]

Does anyone have information or resources on allowable diaphragm shear of reinforced concrete gypsum roof.

I am working on an re-engineering on an existing building dated 1962. The roof system include trussed Tee-4-5-16X21"@32 5/8"o.c. w/ Class "A" poured gypsum reinf. with 4x8x#12x#14 galv. mesh on 1 1/4" fiberglass form board.

Any input would be greatly appreciated, thanks.

 

[BAretired]

I don't think you can rely on the gypsum to carry any more shear that the mesh reinforcement would account for.

BA

 

[Ron]

First of all, you're not likely to find anything using that terminology.

What you have is a "poured gypsum roof deck".

This has been discussed many times in this forum. Go to the main forum page and put in the search term "gypsum" in the search box. You'll get lots of threads discussing just what you need.

As for the "reinforcing"....it is essentially "chicken wire" fencing. It is only there to provide minimal crack resistance for the gypsum and to make it integrally tied to the bulb tees. The primary structural capacity of these roofs comes from the open web joists and the perpendicular bulb tees. The gypsum is primarily there as a fire retarding, nailable roof deck for application of a built up roof system.