LH Longspan Joist Notation

[astepp]

I have a roof plan for a building constructed circa 2005 which denotes the LH-series longspan joists as the following:

48.5 LH
50.0/48.5 LH
51.5/48.5 LH
53.0/48.5 LH
54.5/48.5 LH
56.0/48.5 LH

This is obviously different from the LH joist notation that I am used to seeing (e.g. 48LH15). Is anyone familiar with this notation, or know how to correlate it with the typical xxLHxx notation?

It's possible that this is specific to this planset, I don't have the full roof plan so it's possible there's a key or schedule in a "plan notes" block somewhere else on the sheet.

Thank you.

 

[jittles]

Are the joists tapered? That could possibly be the depths at each end of a joist.

 

[astepp]

Yes, I think they are high/low steel depths. The roof is flat but the plan shows a hipped taper which would make sense, if the 48.5 LH is level at the bottom of the hip and a 56.0/48.5 LH goes up to the ridge. Thanks.

 

[DaveAtkins]

I have never done it, nor have I ever seen it on anyone else's plans, but I think it is possible to just give a joist depth (e.g., 48.5LH) and have the joist supplier design the joist. In a case like this, with sloping top chord, that would make sense.

DaveAtkins