Building A Bridge

[Robert_in_NY]

That might explain the Lackawana stamps then. These steel plants were all before my time.

 

[dynasim]

Koop,

That is a lot of concrete!

Thanks for sharing your project. I am more than a bit jealous.


Chris

 

[patrick_g]

Patrick_g,
We hired a VDOT contractor to do the work so the stick built forms were his call. As a builder myself, we use metal forms but we do not do a whole lot of concrete work. (mosty footers) Tell me more about the "snap ties" and cam locks.


We have settled on green for the color, and the bridge was primed today. New pics coming soon.

Great color choice!

Snap ties are metal rods available in several lengths. They have plastic cones pre-attached near the ends. The ends are formed into tear drop shaped loops. They are used to control the thickness of a wall. They hold the two sets of forms that define the two sides of the wall at a well controlled and securely held distance apart. They are typically used with reusable plywood sheets that are predrilled to accept the plastic cones. The cam locks are, well, locking devices with levered cams that allow you to easily tighten the system or to break it down later.

You can use regular plywood by driling your own holes. The pre-drilled stuff to which I refer is intended for forms and has a slick coating on one side so it lasts through many more reuse cycles than exterior or marine ply.

You do use 2x4 dimensional lumber but it is not nailed as it is held in place by the cam locks and so it can be reused many many times or used later for other purposes. After the crete cures and you remove the cam locks you can pull off the forms leaving the snap ties in place sticking through the crete horizontally. The snap ties are prescored near the loop onthe end but below the surface of the crete.

You bend the end of the snap tie sideways and break it at the pre scored location. Then if the plastic cone hasn't popped our you pop it out with a screwdriver or claw hammer or whatever. There is then a pattern of little cone shaped depressions in the crete and you can see the ends of the snap ties. If you need better cosmetics you can fill the holes but it is not required for structural reasons.

Water under pressure can leak through where the snap tie penetrates the wall but in many applications that doesn't matter. My basement floor is about 3-5 feet below the surrounding water table, has no sump or pump, and does not leak through the snap tie holes. I do have French drains and a drain promoting drainage on the outside of the concrete walls so water drains vertically down and doees not produce a head of pressure. I filled some of the holes left by the cones in the snap tie system on the inside of the basement for cosmetics (covered top 4 feet of wall with thin carpet and didn't want the holes to print through or be felt.)

There are companies that rent the cam locks if you don't have enough use to warrant buying. Metallic forms are terrific but snap ties and associated stuff is cheaper if you can't amortize the expense of metal forms for tall walls. They definitely are not rocket science and work quite well. The work goes fast and the results are good.

Pat

 

[bindian]

Brandi,
You had me laughing for a long time, thanks for the reply.
We have settled on green for the color, and the bridge was primed today. New pics coming soon.

Koop,
Glad I could help. You can always still do the red and green at Christmas.
hugs, Brandi

 

[Renze]

Renze,
Your input has been invaluable to me. You are looking at a 2' thick abutment wall which is 10' tall and 15' long. It sits on a 4' thick, 8' wide and 17' long footer. Both have two mats of 5/8" rebar on 1' centers. This matches or is greater than the state bridges up and down steam from us. Let me know what you think.

Koop,

So in the pictures, you already backfilled over the slab foundation which cant be seen in the pictures ? I was worrying that you poured directly onto those loose rocks
4" with rebar is a good slab.
I really couldnt tell from the photo, that the wall is 2 feet thick... my first guess was 4 to 5" ...

So how high is that wall ? if the width is 2 feet instead of 6 inches, the height must be about 5 yards instead of the 2 i'd guess from the picture ???

So you're expecting earthquakes ???

 

[machmeter62]

Just got the word from the Department of Environmental Quality that no permit will be needed.

My heart goes out to all those affected by the bridge collapse along the Mississippi. This tragic event is particularly sobering for anyone in contact with a steel truss bridge. How does it happen on a state bridge that is frequently inspected?

There was a report of the severe physical and mental abuse the inspectors endured because of required lane closures; the bridge undercarriage was never cleaned properly, and etc. Nobody wanted to do the job there in that environment!!? It will always be the "finger pointing" issue, because of the preparation costs that were deferred?

 

[machmeter62]

There was a report of the severe physical and mental abuse the inspectors endured because of required lane closures; the bridge undercarriage was never cleaned properly, and etc. Nobody wanted to do the job there in that environment!!? It will always be the "finger pointing" issue, because of the preparation costs that were deferred?

Bat and bird waste is a real problem in the under carriage for bridge inspections, and is difficult to remove too!

 

[patrick_g]

I wonder if over the useful life of a bridge you wouldn't be $ ahead if the bottom side were sheeted in with hinged panels. No bird or bat sanctuary, easy inspection. Even barn swallow colonies could be removed with a tank truck spray rig. Small hole style expanded metal would save material and drain water if solid sheeting were a problem.

Pat

 

[koop]

Bridge has been painted and is now sitting on its new sub structure. I will post pictures shortly.

Thanks everyone for your input.

 

[riptides]

Thanks for sharing your project. I learned quite a lot.

-Mike Z.