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Special loads on trusses

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RontheRedneck

Specifier/Regulator
Jan 1, 2014
223
Today I spoke with the EOR on a job we're providing wood roof trusses for. We had done sealed drawings on the job and sent them in. The EOR specified drift loads. He was asking if I had put them on the trusses or not.

Can't say that I blame them. The typical one page truss drawing doesn't show a graphic representation of the loads. Here's a screen cap:

A1_truss_-_Screen_cap_from_sealed_drawing_uautb8.jpg


I emailed the engineer who seals the drawings. Got a fairly obnoxious response, saying that any competent engineer ought to be able to interpret those numbers easily.

I think that's wrong. Not every engineer deals with trusses every day. Figuring out all those numbers and where they fall on the truss isn't that easy.

What do you guys think?
 
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I don't think it would be wrong to include a single line that says 'Drift Loads' to add clarity. But it seems like this is just a minor scrap, you had designed the trusses for drift, it is shown on your calcs albeit not clearly labeled. :shrug:
 
I agree with your engineer who seals the drawings.
 
Anytime anyone says "any competent XYZ" I immediately doubt whatever they're about to say. "Any engineer with significant experience in designing buildings with wood trusses in snowy regions" is one thing...but I bet somebody from Florida wouldn't have a clue what that is.

I agree with drift - better labeling would be nice. But a quick screenshot and a note saying 'it's right here' works, too. If doing that the first time with each engineer is more expensive than adding a custom line on the calc page, the calc page will get updated.
 
I'm feeling more adversarial today than driftLimiter. Maybe it's because we're having a hell of a storm coming through that will impede my ability to make my hockey game on Saturday morning so I'll need to leave at 5am or so to leave enough time. Or maybe it's that I hate proprietary programs that throw-up calculations onto the page. But whatever the case lets have at it!

I agree with you Ron. The numbers are interpretable in the sense they are clear about the force considered but not at all what they are do to. Knowing the truss layout (which presumably the EOR has) would aid the ability to identify if there was anything obvious other than drift responsible for the special loads but even still, wtf just label where the hell the load came from.

On the other hand the stamping engineer probably got $100 so there is that to consider.
 
I think the EOR would be able to figure out that these are snow loads. Any competent engineer puts snow load on the bottom chord.
 
driftLimiter said "I don't think it would be wrong to include a single line that says 'Drift Loads' to add clarity."

Those drawings are produced by the software of the company that did the seal. (Alpine) I do not have the ability to alter the drawing(s) in any way.



 
kipfoot said:
Any competent engineer puts snow load on the bottom chord.

I've always done this. It's a nice fail safe in case you have any localized failure of your roof sheathing, then you know your bottom chord can take the snow load.
 
RontheRedneck said:
Those drawings are produced by the software of the company that did the seal. (Alpine) I do not have the ability to alter the drawing(s) in any way.

Okay. I mean the truss engineer does have a point. One would think that an engineer reviewing these would say something like "Hmm special loads, what could that be. Oh its a tapered load, Duh its the drift that I specified." If the EOR can't do this then he probably doesn't understand anything he is reviewing on that printout.

But I am not one to advocate against clear communication. Just because you cant edit that calc plate doesn't mean you couldn't provide a statement that drift loadings per the drawings included as 'Special Loads'.
 
Clear communication is what I'm after. Seems like a reasonable thing to expect in a professional setting.
 
driftlimiter said:
Okay. I mean the truss engineer does have a point. One would think that an engineer reviewing these would say something like "Hmm special loads, what could that be. Oh its a tapered load, Duh its the drift that I specified." If the EOR can't do this then he probably doesn't understand anything he is reviewing on that printout.

Absolutely!
 
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