Starting my bridge!!

[dodge man]

I remember my structural analysis class and having a homework assignment where you would break down the loads on various structural members of a truss. The homework was usually just a small part of a larger truss and it would take 3 or 4 hours to work the problem. The good part was I never studied for the test, the homework took care of it. I somehow assume computers have shortened the work load on this.

 

[Doorman63]

I’m not sure if you guys are having all this math and engineering chat because you think my bridge is worthy of all this chat…….or I’m an idiot and it will buckle and actually catch fire!!

All these other ideas give me a lot to think about.

As far as clearance under the bridge…..during construction when standing in the center I’d estimate 4.5-5’ to bottom of span. I don’t really get any large debris after a heavy rain. I’m not too concerned about clearance under the bridge.

 

[ning]

Works just like a truss, but upside down. The load is straight down on the end pillars.

Down, and in towards each other

The tension (diagonal) is made up of the vertical ("load straight down on the end pillars") plus the horizontal arrows (compressive force on the rail).

 

[ning]

I’m not sure if you guys are having all this math and engineering chat because you think my bridge is worthy of all this chat…….or I’m an idiot and it will buckle and actually catch fire!!

All these other ideas give me a lot to think about.

As far as clearance under the bridge…..during construction when standing in the center I’d estimate 4.5-5’ to bottom of span. I don’t really get any large debris after a heavy rain. I’m not too concerned about clearance under the bridge.

Yeah but having a king post sticking halfway down to the water would look really strange! Anchoring it to the top of the side rail gives a good excuse for a rail and looks good as well!
Aesthetics matter more than functionality, don't forget.

 

[Doorman63]

Yeah but having a king post sticking halfway down to the water would look really strange! Anchoring it to the top of the side rail gives a good excuse for a rail and looks good as well!
Aesthetics matter more than functionality, don't forget.

Aesthetics……I’ve told people before…..
It’s a bridge in the woods NOT the Eiffel Tower.

My current issue…….I’ve used all my long lengths of tube steel.
I may have 2 17’ish long pieces.
I can make a railing that would help with structural support but it would have to be pieced together.

So if you wizards (do engineers like to be called wizards?) can draw something with 2x5 tube/rebar/gusset plates/spit and blood…….I’m game

 

[ning]

Aesthetics……I’ve told people before…..
It’s a bridge in the woods NOT the Eiffel Tower.

My current issue…….I’ve used all my long lengths of tube steel.
I may have 2 17’ish long pieces.
I can make a railing that would help with structural support but it would have to be pieced together.

So if you wizards (do engineers like to be called wizards?) can draw something with 2x5 tube/rebar/gusset plates/spit and blood…….I’m game

The railing doesn't have to be that strong. The end supports need to be able to carry whatever weight you're transferirng to the tension rods (easy, that's not much) and the railing needs to be sturdy enough in compression not to buckle. Neither of these are dealing with a multiplied force like the tension rods.

A couple of wood 2x6's is probably sufficient in compression if you can stiffen them, that's why I suggested that if you had more of the 2x6 tube that filling it with concrete would stiffen them. If the end supports are well anchored that would also help, but really this is the lightweight part of the design, just put something between the uprights that'll stay between them.

 

[dodge man]

Just don’t call an engineer an architect and you’ll be fine.

 

[Doorman63]

Just don’t call an engineer an architect and you’ll be fine.

Architect……..I drew a picture nobody can build!!

 

[Doorman63]

Railing idea

 

[LD1]

Put a couple angled pieces in that handral and you have essentially built a 40" tall truss....which will be ALOT stronger than just the 2x6 bottom tube. Maybe to the point of needing nothing more