Existing Joist Size: DH series?? 2

[sbrg]

I am doing some preliminary investigation on an existing roof structure of a foundry, era 1970. The existing plans indicate that the joists are 28DH9's spaced at 4'-9" and span 50 ft. The total roof load on each joist is in the 280#/ft range when adjusted for drift load from a proposed addition with a maximum reaction of 8.4 kips. I have researched the Steel Joist Institute's historical manual and have not found a match for a 28DH09. I have found LH, LJ, J and H-series that are 28xx9, but no DH-series. My guess is that it is an error on the plans and is probably either the H or LH. There is a significant difference in capacity with the 28LH09 at 463 #/ft and the 28H9 at only 267#/ft. Does a DH-series exist?

 

[Ron]

Check the joist tags on the end of the joist...this will give you the correct designation. The tag will be wire-tied to one end of the joist.

 

[nhstruct]

If you can measure up the joist, the SJI website has a form that you will out, and they will get back to you on what they believe the joist is based on the measurments