New 3 Sided Box on Existing Abutments

[blanchardMSU]

I am currently working on a design for a super structure replacement of a 27ft single span bridge. At this point the CIP reinforced concrete abutments are in great shape but the 65 year old steel beams are shot. We are considering cutting the top 18 to 24 inches off the abutments and replacing the tops of the abutments and the super structure with a PCC three sided box. This will allow for partial with construction and a overall shorter delay to my residents. Any recommendations or experiences with this type of restoration would be appreciated. Scour is not a factor in this case.

 

[RHTPE]

Why not consider precast concrete box beams side-by-side and cover with a finish slab?

More pieces to set, but certainly less weight for each crane pick.

In either case, you need to consider how you make the connection of the new to the existing.



Ralph
Structures Consulting
Northeast USA

 

[Qshake]

Three side boxes are expensive so make sure your residents are very put off by the detour necessary to close the road to remove and replace the bridge.

Many a bridges have been replaced with RHTPE's suggestion. And with the short beams the whole matter of transporting and setting beams can be done in a day. With the beams set and they usually ship with the barrier on them, you're ready to drive on them. Then you can close on side and place the concrete or asphalt topping. Next day do the other side.

The only real time delay is to deal with the existing abutments. You'll have to demo to a specific elevation (with consideration for beam depth) and then probably pour a leveling course over the demo portion. Erect beams atop inexpensive neoprene bearings.



Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[bridgebuster]

I agre with Ralph & Qshake. No reason why a precast concrete superstructure shouldn't work. I had something similar a few years back. At 27' you could even cast the beams on site if you have room.

 

[ACtrafficengr]

We had several concrete box beam bridges reach the end of their design lives recently, and have become leery of them, due to the difficulty of inspecting the internal boxes.

High Concrete (an affiliate of High Steel) has developed a precast beam system that we've been looking at.

http://www.highsteel.com/products_and_services/next_beam/index.cfm

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

 

[blanchardMSU]

Concrete box beams would work but I need this road open fast it gets a LARGE number of heavy trucks, due to a border crossing near buy. I think there will be problems with the center line joint if we have traffic running on one side of the bridge during the cure time for the slab.


My county had dozens of those double-tee beam bridges and we have had nothing but problems with them. A local supplier started making and selling them to us in the late 70's and buy the mid 80's we refuse to install double-tee ever again. We have had to replace most of them already and the rest of them are on a short list.

Thanks to all for the input !!

 

[ACtrafficengr]

I had to laugh.

My county is leary of concrete boxes because of trouble with early examples built in the early '80s.

Your county is leary of double tees because of trouble with early examples built in the late '70s.

In both cases, I'm sure the technology has matured significantly since then, yet once bitten, twice shy...

Anyway, FHWA is pushing accelerated bridge construction. Some extreme examples installed a bridge in a week. This sounds like just the ticket for your project.

http://www.fhwa.dot.gov/bridge/accelerated/

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928