Building a covered work area with a 40' span, will this work?

[STx]

Do you know someone who is actually a structural engineer? The calculations are fairly simple, but I think this project needs to be analyzed. As a first step, I would go with a full scissor truss instead of the tie approach you started with. You are going to have a real potential for the rafter to buckle where the tie connects.

I wish I did. I've contacted a few but none seem interested in such a little project. I'd be happy to pay someone to do the design if I knew someone that was willing to deal with such a little job.

 

[LD1]

Seems like alot of cutting, notching, and welding to use a small diameter pipe for the trusses. Weld quality will lso come into question.

Then in the end, your left with a building that insurance likely won't cover if anything were to happen.

My 40' trusses for 4' OC were somewhere around $180 ea IIRC

 

[STx]

About 1/2 of my net income comes from steel fabrication. It'll be a lot of work but it shouldn't take more than 2 or 3 days to build them once I get the first one done and make a jig. The notching goes pretty fast and I've got a tube bender also that I can use for part of the internal truss supports to speed things up and cut down on the notching. I've had some of the stuff I've built in the past damaged by shipping companies, it always tore the steel somewhere, the welds never broke so I have confidence in my weld quality.

I'm not too worried about insurance, I've never had an insurer inspect anything before writing a policy and this would be part of a homeowner's policy, not a commercial one. I'm honestly more concerned about theft of the contents.

The nice thing about doing it myself and having a jig to build more in the future is it'll make expansion or future projects go pretty quickly.

 

[Streetcar]

Stx
With your design the pipe will act as a beam not a truss. I do not know the strength of the pipe to know if it will work as a beam
The cost for an engineered design and material would probably be higher than the cost to buy trusses
Four foot spacing on 2x4 to support metal roof is not adequate

 

[Leejohn]

Watch out for this guy, plan for it now.

 

[CurlyDave]

I would google "steel truss design" and see if I could find a pre-done design and then just copy that.

If I just search on "truss design" I get mostly wood trusses. My experience with wood is that a local shop can usually make them for less that the cost of materials if I buy the lumber. Plus they are already made up and have an engineer's stamp on the drawings.

I would not try to make these myself, no matter how good a fabricator I was. You really need an engineer to calculate the design.

 

[LD1]

Four foot spacing on 2x4 to support metal roof is not adequate

Since when

 

[STx]

I've been looking at some steel structures with steel trusses online. A lot of it on really long spans, like aircraft hangers, has webbed beams with horizontal cross supports part way down, sort of like my original plan except that the top becomes a webbed beam. They look to be constructed mostly of angle iron. Then I see some that are webbed square tube but, I also find a lot like the ones I've attached here that are basically just bent square tube with some gussets. I get that these aren't quite as long of a span, although one of these looks to be a little more than 30'. Even given that my span is longer, the fact that pipe is stronger than square tube, and definitely stronger than angle iron, and then add that drill stem is hardened steel (although it will have some internal wear from use) and it doesn't seem like this is really too much to ask of it.

The last picture here is a 40' span. I don't know what the material is but the truss design sure is basic on it and they're spaced much further than 4'.

And here are plans for a 40' span using webbed angle iron trusses.

 

[STx]

Here's a design LSU was nice enough to do for us, I just don't want to waste all that overhead space - 4 ft. Steel Pipe Truss (4.12 Pitch).

They actually have a lot of very useful design stuff for free there. Building Plans

 

[SirReal63]

Our 40' span is like the one in the first pic, but improved upon. 2-1/2" square tubing. If you follow this design, it will be plenty strong. Our building got hit with 50 mph winds last Spring and even with 14' walls it held just fine.