F&A Concrete Joists - Design Manual? 1

[WesternJeb]

Hello All. I have come across some old concrete joists (1955-ish) called out under an "F&A" system. The only lead I have found for any design material is a design manual by Nitterhouse Concrete Products. Does anyone have a historical copy of this that could be shared with myself? It would be much appreciated.

The callout I am interested in is "No. 1067 'F' and 'A' Joists". From the previous thread, I am assuming that these are 10" deep joists, 28" o.c., and rated for 67 psf. Does anyone know if this is a correct assumption?

See a previous thread from around 12 years ago: thread507-292210

 

[JAE]

I'm still looking for a design manual - not sure I have access to it but will look.

I did find the following:

https://www.structuremag.org/wp-content/uploads/2014/08/C-EngrNB-Antiquated-Stuart-Sept081.pdf

https://iibec.org/wp-content/uploads/2019-05-06-hogan.pdf

You might try contacting this company as they appear to be the 1950's originator of the F&A system:

https://nitterhouseconcrete.com/roots-of-nitterhouse-concrete-products/

I'm not sure you can just look up a depth and a span in a load table and get a load capacity, though.
The above documents suggest that the actual reinforcement (prestressing) was varied, or could be varied, for a depth and span condition, creating multiple possible load capacities.

 

[WesternJeb]

Thanks JAE. I also reached out this morning and received the following document from Nitterhouse. I will say that the the previous discussion does indicate prestressed but the Nitterhouse manual indicates non-prestressed, along with the links that you sent.

From the Nitterhouse documents, it seems the designation is joist depth (10"), and then the second set of numbers designate the bars. So for No. 1067, it is a 10" deep joist with a #6 and #7 bar in the bottom of the joists. I verified the capacities with enercalc and their capacities line up with that, as suspected. Have you (or anyone else) had a different experience or understanding than this?

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1702485901/tips/F_A_Joist_Information_Packet_jzsxrq.pdf[/url]

 

[JAE]

WesternJeb - I just noticed that you already had a connection to Nitterhouse.

I've not worked with the product - just saw the in the Antiquated Structural Systems article on it that they indicated a variation in reinforcement was possible.

I'm not sure if that means you call out a "standard" product (with variations of bars as you suggest)
or
You specify a depth and span and a load capacity and the system is custom designed each time.

 

[WesternJeb]

JAE - I do see what you're mentioning in the antiquated systems article and agree that I could see it going either way unfortunately. I do not see any design loading specified in the drawings, but this might have been provided after the contract was awarded, I am not familiar with how things worked back then. Hopefully someone might be able to chime in with their experience.