Framing for trailer floor

[R_Lefebvre]

A triangle is strong for bracing or loads along the plane of the triangle. The triangle has absolutely no strength (same for any other 2D shape) when the load is placed orthogonally or on the face. It is the method of distribution of that load that is important.

That is mostly true, but not absolute. Structures do have some strength orthogonally, and I think if you did an FEA analysis which would be required in this case due to the complexity of the shape, you'd find that a trailer with a diagonal lattice framework would be stiffer than one with straight bracing.

 

[Rbertalotto]

As I look at most home builds on this site, 90% of them are WAY over built for the intended uses. I'm seeing trailers that are 4' X 5' with 3000# axles and 3" X 3" 3/16" wall steel tube. Other than hauling a load of granite blocks, I'm not sure you could possibly overload such a trailer.

If constructed properly, using basic engineering principles, these trailers can be built using very lightweight materials and hold up to a real beating on a trail.

In most cases, the welding that I witness is the weak link in many of the constructions.

 

[ntsqd]

As an aside, the reason behind the 3k axles is not for the 3k load capacity. It is to get bigger wheel hubs and wheel bearings. Off road use deals those parts a lot of punishment. Even under light trailers the lower weight class parts have been proven to have a much shorter lifespan.

Not that I'm volunteering to do it, but if necessary it could be done manually too. It's not that complex of a shape. Simple, fixed beams with distributed and point loads. The torsion incidences due to the eccentric loadings would be the hardest to integrate into the result.
Where's my FEA dongle......

 

[R_Lefebvre]

As I look at most home builds on this site, 90% of them are WAY over built for the intended uses. I'm seeing trailers that are 4' X 5' with 3000# axles and 3" X 3" 3/16" wall steel tube. Other than hauling a load of granite blocks, I'm not sure you could possibly overload such a trailer.

If constructed properly, using basic engineering principles, these trailers can be built using very lightweight materials and hold up to a real beating on a trail.

In most cases, the welding that I witness is the weak link in many of the constructions.

As already stated, the 3000lb axles are for the bearings, not the axle itself. 2000lb bearings have been proven inadequate in many cases.

And where are you seeing 3x3 frames, and 3/16" wall tube? I don't think I've ever seen a 3x3 here. 2x3, and 2x2, yes. I used 2x4, but in 1/8" wall, and I did it because my trailer is big and fairly heavy.

I think you're underestimating the stresses put on a trailer being pulled across dirt roads (washboard).

 

[indiedog]

That is mostly true, but not absolute. Structures do have some strength orthogonally, and I think if you did an FEA analysis which would be required in this case due to the complexity of the shape, you'd find that a trailer with a diagonal lattice framework would be stiffer than one with straight bracing.

Hi Rob. My comments are only for static loads applied vertically to the trailer floor and that's without consideration of what sort of framing is used. I've no doubt that triangulation would add stiffness for dynamic or lateral loads. I still stand by my observations though.