Old Light Gage Framing Floor Purlins 1

[camber]

I have a building designed in 1949. The floor framing plans indicate a 9"-13ga -24" o.c. for the floor framing. I am assuming this is a 9" deep 13 ga thicknes member spaced at 24" on center. In the notes, it indicates provide joist bridging per manufacturers instructions. Anyone have an idea on manufacturers/design properties for this vintage steel stud joist. I have not been to the site as it is a three hour drive and would like to do a little homework prior to heading out blind. The client would like to install a CT scan on this floor. I have my doubts about the capacity and am most likely going to recommend additional steel beams directly under the support locations for the scanner. Any information would be appreciated.

 

[JAE]

That old....I would expect difficulty in getting any significant data on the properties from old books, etc.

I think you have two possible courses of action. One would be to field measure the joists, spans and spacings(using a micrometer to verify gage thicknesses). And field determine the existing dead loads, type of floor deck, etc. Then, using the applicable AISI Code, calculate the load capacity of the floor joists to back check what the original design Live Load was. Then do an analysis to verify the CT weight can be carried.

Second option would be to do a load test on the floor per IBC or other applicable resource.

I would suggest, if possible, doing both of the above to confirm each other.