I Can't Do The Math

Great idea.

 

Well, I didn't get the building. The deal sounded good in the beginning, a 24 X 40 area inside a larger building. Today I found out that not only could I not fix the floor, I couldn't put up a wall around my area. Also if I wanted heat I would have to heat the whole building. Electricity and water were also on the same meter, and it went down hill from there. So, I am back to looking for a place to build.

 

Good luck in the search, what are you going to build?
A boat I hope!

 

I am borrowing ideas from several places as no one really has a plan that I like. It will be a catamaran around 20 feet in length but I am still undecided between a few things and will probably change my mind several time while building it. Boat builder Central has some Cat/Pontoon boats that I like the looks of some things. Bernd Kohler and Richard Woods have some things I like. Since most of my undecided parts are above deck, it may start out by looking like a stripped down pontoon boat with just hulls and deck.

 

I beam loads

I-beam, top & bottom are typical 1x2 (3/4 x 1.5 inch), beam web is 1/4 thick plywood. Beam overall dimensions 6 inch hi x 1.5 inch wide. Glued construction (best to have a 1/4 x 3/8 slot routed into the 1 x 2, insert plywood, glue properly.

Moment of inertia = 17.5 in^4
Beam maximum bending moment at 1080 PSI allowable stress = 6300 inch-pounds.

This beam, with an unsupported span of 60 inches, will allow 420 pounds force as a concentrated center load when it reaches 1080 psi tensile/compression stress. This stress level is close to the maximum allowed for home building lumber.

 

Wow!, Thanks Fred. I know there are people on this forum that can do what seems incredible to me. I sometimes wish I had gone a different direction with my education.

 

Probably be faster and cheaper to just use 3 2x6's. If you estimate that you'll have 4 x 200 lb people on that 4'x5' section of floor that's 50 lbs per square foot live load. I looked up the span table for southern Yellow pine and the lowest grade will get you there on 24" centers. http://www.southernpine.com/app/uploads/SPtable3_060113.pdf