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cutting steel truss joists

cutting steel truss joists

cutting steel truss joists

(OP)
I am cutting three steel trusses (14H4). Is there anything to be concern about except to make sure thet the last web is placed properly? Any toughts?  These trusses are carrying a concrete floor. As far as the loading is concern they are o.k. and by cutting them the load carrying capacity increases.

K&G

RE: cutting steel truss joists

That sounds counter-intuitive. Can you elaborate? Are you shortening the span? if so, it seems that, depending on where you place the new support, the shear in the webs might be problematic.
More info would help.

RE: cutting steel truss joists

(OP)
Thanks for the response. Yes there is going to be a support on masonry walls and there is going to be an angle in diagonal from the last web to the truss bearing point. So that is going to take care of the shear at the bearing. The cutting is to allow for the elevator shaft. A steel beam is added to support the three joists 14" deep this is an interior job and there is no uplift to deal with. I hope this is answering all the unknowns. Thanks agin.

K&G

RE: cutting steel truss joists

I think you should model the joist as a truss as best you can, and if everything works then fine.  Of course, that's pretty generic to say "if everything works, then you're good".  Vulcraft has a book on designing with steel joists you might want to check out as well.  

RE: cutting steel truss joists

(OP)
ucfse, thanks for the input. I was going to do what you suggested. But, I was wondering even if the truss calculations come out to be o.k. is there anything else I have to worry about? I checked the Vulcraft book and did not find anything relating to reducing the span on the steel joist trusses. However, yesterday I made a site visit and found out that all the webs are round pipes 1/2" in diameter. I checked the tag at the end of the joists but it was not useful since the manufacturer is out of business and there is no way I can get any info on the trusses from them based on the tag no.  Any suggestions or guaidance is appreciated.

K&G

RE: cutting steel truss joists

You probably mean that the webs are 1/2" dia rod. I doubt that they are pipe.

Isn't the tag useful in determining what size joist it is?

RE: cutting steel truss joists

(OP)
Yes the webs are 1/2" round bars.
No, the tags are not useful at all. The tag is put in by the manufacturer and unless you call them or have the shop drawings they will not give any size or type. As I mentioned before the manufacturer is out of business since 1980.  However, this is for all who might run in to the same situation, I called the SJI in SC and talked with them after I gave all chord dimensions, top and bottom,  the webs diameter, and the distance between the webs they were able to verify the type of the bar joists. So, in case some of you come across the same situation your best bet is to call SJI do not just rely on the tags.
thank you all.

K&G

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