Odd Steel Joist

[HokiePE]

I have a project with some odd steel joists that I have never seen before. The roof joists are 32" deep with WT5 top chords and WT4 bottom chords. Floor joists are 36" deep with similar chord configuration. Does anyone know where I can find information (span tables, load capacity, etc) for these type of joists?

 

[Deutero]

Depending on the actual WT designation, these seem to be large joists? Are they in an industrial occupancy? Could it be that they were designed by an independant engineer as opposed to an SJI manufacturer?

If there is anything fortunate about these joists, the shapes are at least something possibly recognizable by AISC shape and material, such that you might be able to calculate the section properties, if necessary. I've seen some very unusual chord shapes, that if not for the ID tag, one would have great difficulty determining their capacity.

Curious ...

 

[jike]

Check to see if there is a joist tag (at either end). This should give you the manufacturer's name and joist size.

If no joist tag, then it is likely a "fabricated" truss.

If it is a standard SJI joist, then you should be able to either use current load tables or the "SJI 70 Year Digest".

If it is a non- standard joist (not conforming to SJI) then let us know who the manufacturer is and someone here might be able to help out with load tables.

 

[HokiePE]

Oh Sorry, I should have been clearer in my first message - this is for a retail facility. More specifically, it is a restaurant/dining space that they are converting to a gaming room (slots).

The joist definitely do not seem to be SJI standard nor by a SJI Manufacturer. I did not see joist tags, but my access was limited at the time. I did see the ends of the roof joists and did not notice tags. The joists are large, but the depth seems consitent with LH series joists for the same span and loading conditions.

My dilema is that they are putting these slot machines up there and I have to verify that the load capacity is OK . . . which I figure it should be if the floor system was designed for 100 psf. The machines weigh 265 lbs each, so my calculations indicate that the total load will be well under 100 psf (accounting for the space taken up by the machines). I just need to be confident that the floor was actually designed for the 100 psf load. Am I worrying too much about something that I should not worry about?

 

[JAE]

Don't forget that in addition to your slot machines weight, you also have public assembly 100 psf live load between them.

 

[UcfSE]

Checking weights and worrying about whether existing structures will work is not bad. After all, once you give the OK, it becomes yours.

I've seen joist girders with WT's for chords but not very often, and not for regular joists.

 

[jike]

I have seen L or LA joists one time, in a box plant built in the 50's, that I believe had WT's as chords and single angles for webs. If I recall correctly, these were built by Havens Steel.

 

[ironmon]

What I would recommend is that you get all the member, chord, and web sizes and geomerty and model the joist in a program like RISA.

http://www.risatech.com.

check the stresses, compression, tension and possible combined bending and compression in the top chord.

also make note of the weld size and length at critical elements, usually the last web members.

in addition if the joist is overloaded, you will have to check the joist bearing ends.

Ironmon