Is poplar a suitable wood for trusses? (Pole barn, 5 ft spacing,7 inch top and bottom cords.. air dried to under 10%)

I not sure what kind of poplar you have but its normally not used for structural purposes simply because it likes to bend. There are stress grades of popular. Here is some stats and info on poplar

http://www.fpl.fs.fed.us/documnts/pdf2001/balat01a.pdf

Another thing is normally a pole barn truss is 4' O.C. or less and then perlins.

What is the clear span? And what is the truss style here. You may need rated stressed lumber for this depending on the size and truss design.

Span is 30 ft, w truss. Posts on 10 ft are common with trusses on 5. This would be native poplar.. in Tn.

And thanks 21 boat for the answer and the link. I read it all, very informative. I may build one truss, prop it up and load it. The design is so overkill that I believe it would be allright.

What's the spacing on the perlins and what truss design do you have.

Are you using gusset?

What are you using for gussets?

I build pole buildings here and just curious. Last one was 39' clear span 60' long

Is there a king post involved in your truss design?

A "W" truss,no king web. Gussets are 3/16 inch steel plates bolted, 24 inch spacing perlins.

I don't know your geo but 5' hear O.C. truss spacing doesn't work. What is the pitch?

I have a 5 ft now, my last shop was 10 ft center trusses. You may be far enough north where snow load makes a difference. National barn built the one I have here on 5 centers. They have a web site. Big company. My last shop the pelins were dropped between the trusses on joist hangers. 2by 6 perlins on edge.