any structural engineers?

i-wagon

Well-known member
Looking to rebuild my utility trailer as it's factory gvwr is a joke and it's bending where the tongue attaches. Rated for a ton, never had more than 1300 gross. it's current construction is 1-1/2 x 1-1/2 x 1/8 angle, cross members every 20", total size 5x8. MY plan would be to go 5x10 (reuse ramp, axle, fenders, springs) keep the cross beam spacing but build with 2x2x 1/8 square tube. In theory (in my eyes) there's twice as much material in each direction, so it "should"be significantly stronger. Looking for professional input before I buy stuff and start welding it together

 

blehhh

Active member
I'm a structural engineer. Any pictures of the trailer?

The increased depth of the 2" vs 1.5" goes a long way in terms of both stiffness and strength.

Piece for piece, a 2x2x1/8 tube will be more than twice as stiff as a 1.5x1.5x1/8 tube, meaning it would deflect (sag) half as much if you were trying to walk across it, etc, (based on their respective moments of inertia). 

The actual strength, or load at which it would start to bend and actually stay bent (inelastic yielding), is almost twice that of the 1.5x1.5x1/8, ( based on section modulus).

 

i-wagon

Well-known member
I don't have pics of the trailer ATM, but they sell the same thin at Lowes and tractor supply. I didn't believe angle iron would last, but figured they wouldn't rate it higher than what it would handle. Also, I planned on having the tongue be 2x2x 3/16 with braces going halfway down, and having it connect to all cross pieces to the mid point. Currently three tongue only attaches to the very front and one brace 16" back

 

i-wagon

Well-known member
I can get pics of my plans I have drawn up, once I put in where the axle will be. Be easier if I still had access to autocad

 

i-wagon

Well-known member
alright, this is just about how i plan to build it pending cost

hmNU3IX.jpg
top view. tongue will me welded on the bottom of the crossmembers, tongue braces as well. sides  will be reused and extended from existing stuff. the actual welder from work figured a couple hundred dollars in steel, and i figure a hundred in 5/4 pt decking. i'm hoping it won't cost that much for steel, because if so i wont get to do this any time soon. what i can do is flip the thing over, smack it where it's bent with the backhoe and brace it, but bigger is definately coming my way, and i can build the above for half the cost of the same thing half the strength

 

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