Welding Tips and Tricks

Hey guys, I'm Jody.... I'm pretty much a hobby fab guy, but things are picking up a bit for me in that department. That brings me to the question-

How do you KNOW what your building is strong enough? I've searched for articles and apps, but I'm having a hard time finding anything besides tensile and yeild strengths. Maybe the info is there, but I just didn't know what I was looking for...

I'd like to know the limitations of DOM, square and rectangle tubing and the calculations to help me determine wall thicknesses for the different applications.

I did find Beamboy, but that seemed pretty limited as far as selecting wall thickness and tubing style.

Any help or links will he greatly appreciated.

EDIT: Some of the projects I have but need to determine strength:
40" Wide press and brake for 1/8"SS sheet parts
One man kart lift (racing go-karts)
Shop crane extensions
Ect...

I had the same questions a few months ago and another poster(jpence38) sent along these sites...

http://www.steeltubeinstitute.org/pdf/b ... le_bro.pdf

and

http://webstructural.com/how-to/steel-beam/

Man THAT is EXACTLY the kind of response I was looking for! THANKS!

Now I need to spend some time learning what all the abbreviations and inputs mean.

Most places (Steel Shops) Would be able to tell you what the strength of the materials they are selling you. Any where you would be buying beam material can tell you the same. And actually if you think you need it they can up the pounds per foot for you. Good info to have me thinks.