Reverse Engineering for Trusses

[ecoplnr]

I'm designing / building a house for myself in Southern Arizona. The house is a contemporary 'quonset' style metal structure and will span an arroyo (approx 60' length; one 30 span in the middle and one 15' span at each end). Trusses will be under the floor slab (6" light weight concrete / 3" metal pan), plus a ridge truss creating a lengthwise clerestory between different radii (one is 16' and one is 12').

Now, for the challenge; I've purchased some surplus trusses (from a third party), but don't have all the engineering / materials specs for them (when purchasing, I thought the tech data would be complete). I do have fabrication drawings (attached), but not materials specs, DL or LL calcs, etc. I've contacted the mfg but cannot get them to return my emails.

Might it be possible for someone to look at what I have, determine the LL / DL, and tell me what the required engineering values would be?

Thx, ecoplnr

 

[TLHS]

It's possible, but nobody's going to take that liability or do that work for free. You're going to need one on this project anyway.

Hire a local structural engineer.

Also, it's not a good idea to buy major items before you've done the design work. You could spend more trying to make them work than you saved by buying them on the cheap.

 

[TLHS]

Somehow I put sentences in the wrong order?

You're going to need a structural engineer on this project anyway, is what I meant to say.

 

[CBEngi]

It's been my experience with Pre-Engineered Metal Trusses in Canada that typically our cold formed steel code gives two options:

1. Design to the code.
2. Design how you want, then test to prove it's accurate.

When you building thousands of trusses each year it’s typically more economical to pick the second option. Thus we always run into the trouble of reviewing previously completed roof projects and the code analysis never gives the capacity it should. The manufacture would know best, I think it’s worth trying to get the design loading from them before getting a Structural Engineer involved.

 

[ecoplnr]

Thanks for your valuable input. I will pursue, as suggested. I'll post progress, FYI Thanks again.