Nomenclature for Joist

[Perception]

Hello everyone,

I am looking at a set of plans that are using custom designed joists for a roof. I don't have as much experience with the nomenclature for custom joists. On the plans there are joists called:

Joist Designation = 96G14N12.8k

On the roof, 2 simply supported beams frame into these joists (1 beam from each side) at 13 locations along the length of the joist. As I understand it the 12.8k denotes the reaction force of the beams coming into the joists. Does the 12.8k include the reaction of both beams or just one? Also, does the 14 denote that the joist spans across 14 spaces?

Thanks

 

[jdcollins]

This is the nomenclature for a "Joist Girder."
In your case, the joist girder is to be 96" deep, with 14 joist spaces, with a load of 12.8k at each location. The load should be total load, but you could easily check that against the design dead & live loads from the drawings.

If this is a set of structural drawings, then this is likely just the design intent that is provided that the delegated joist engineer will use when designing the joists and joist girders. This is not an exact joist design. That will generally be provided in the joist shop drawings.

 

[DETstru]

The 12.8k is the total load at the node.

Is the "k" capitalized? One thing to note is (I believe) the "K" at the end indicates an ASD load and an "F" at the end indicates an LRFD factored load.

 

[JAE]

"k" is for kips

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[DETstru]

JAE, I'm aware it's kips but the nomenclature changed with LRFD to indicate if the load was an ASD load or LRFD load.

If the expectation was to design in LRFD the designation may have been something like "96G14N17.9F"

 

[JAE]

DETstru - sorry, you are correct.


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