Starting my bridge!!

[ning]

A “truss” design seems to make the foundation less important.
...
Can I eliminate the top tube, replace with angle iron and a wood cap?
If what I’m reading you guys are posting it seems that my be an option.

Truss or tension rod both have the same foundation needs, unless you're sinking an end post into the ground (unnecessary).

Either (right side post in drawing) there needs to be a member between the two upright end posts that can stand your load in compression, or (left side post in drawing) a diagonal brace serving the same purpose (can still have a light handrail).

Neither affects the foundation; all load on the foundation is as it was when you started this thread. Anchor one end of the bridge, maybe both ends (one side have slotted anchors? idk), with some way to account for thermal expansion of the bridge and it flexing under load.

> ning
> your design adds a lot of new forces that must be accounted for to safely cross the bridge. It is not as simple as you think it is
I'm wearing a parachute

 

[Doorman63]

Truss or tension rod both have the same foundation needs, unless you're sinking an end post into the ground (unnecessary).
View attachment 790138
Either (right side post in drawing) there needs to be a member between the two upright end posts that can stand your load in compression, or (left side post in drawing) a diagonal brace serving the same purpose (can still have a light handrail).

Neither affects the foundation; all load on the foundation is as it was when you started this thread. Anchor one end of the bridge, maybe both ends (one side have slotted anchors? idk), with some way to account for thermal expansion of the bridge and it flexing under load.

> ning
> your design adds a lot of new forces that must be accounted for to safely cross the bridge. It is not as simple as you think it is
I'm wearing a parachute

I’m planning to pour a concrete approach/abutment on one side for sure.
The other side is more difficult to get concrete too. I could fab a chute to get concrete across the bridge. May end up being some old Schlub mixing it by hand…….

Maybe some sort of grade beam/small slab on the far side with some slotted tabs for anchors in the concrete.



I can definitely duplicate either or both sides of your pic @ning

 

[Streetcar]

For a short span bridge you don’t need to worry about expansion at you abutments

 

[ning]

For a short span bridge you don’t need to worry about expansion at you abutments

Double checked: 0.06% expansion over 100F; that's 1/8" for 20' length change from 0F to 100F: Agreed.

 

[Doorman63]

Back at the farm by myself with my work truck, welder, a truck full of steel “stuff” and a decent weekend weather wise to work on the bridge


Was chatting with a fellow ironworker today and my bridge came up.

He and another guy built a bridge to support a 11,000 pound truck.

They made “trusses” for the spans similar to what I’ll do.

He recommends cutting the end posts short and “bowing” the railing when I weld it. Then weld in my bracing.

Any thoughts on this idea?

 

[bcp]

Can you post a diagram of your planned trusses?

Bruce

 

[Doorman63]

This is pretty close.
Some angles on the ends going down to the stringers

 

[bindian]

I think you need to stick to ironwork. Your troll drawing looks like it has moose antlers.
hugs, Brandi

 

[Doorman63]

I think you need to stick to ironwork. Your troll drawing looks like it has moose antlers.
hugs, Brandi

Everyone’s a critic…..

 

[bindian]

Everyone’s a critic…..

But the deflection tolerance is within margins.
hugs, Brandi