Integral Bridge

[jackietsui]

Hi everyone,

I am very young to the bridge engineering and i may ask silly questions here.

What are the advantages of using an concrete integral bridge over other types of bridges?? I know corrosion prevention is a pretty good reason, but are there anymore?

What do you have to pay attention to design an integral bridge??

Thanks for help!

 

[amorrison]

http://images.google.ca/images?hl=en&lr=&ie=UTF-8&q=integral+bridge&btnG=Search

 

[Qshake]

Integral bridges have many more benefits as you had likely thought. While I recommend that you visit the Bridge FAQ listed in this section for reference material I will also note a few of them.

First and foremost is the low maintenance and degradation of integral bridges. Without a way for water and chemical deicers to enter onto the substructure it remains nearly as pristine as when it was first placed.

Bearings used with integtral bridges are significantly less costly since the load is transfered only partly through the actual girders. Thus most bearings are simple 1/2" (13 mm) neoprene pads as opposed to steel plates with neoprene or even other all metal bearings.

Without expansion joints, seismic shelf space is not a concern. One of the first lessons learned in the 1971 San Fernando Earthquake was the vulnerablility of expansion joint shelf space and the resulting span loss.

These are just a few, I'm sure there is more.

Regards,
Qshake

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

 

[ghghghgh]

Another potential advantage is continuity, even if only for LL. The reduced mid-span moment may reduce your section and provide some cost savings.

 

[Isntbard]

There is a good article here:

http://www.steel.org/infrastructure/bridges/integralabutm.pdf

If your bridge is on piles so that the piles can flex to take care of thermal movements integral bridges are the way to go. They eliminate expansion devices and bearings that cause problems. If your bridge is long the pavement at the ends could be damaged by the thermal movement. Each state DOT seems to have its own preference on how long a bridge can have integral abutments. Bridges up to 200’ are very commonly built with out joints. Tennessee has a bridge over 1000 feet with out joints.

Qshakes comments above are excellent. The only thing I would add is that if you are in a high seismic area you should check shear at the joint just below the girders.

 

[oldmanK]

I'm doing some field and analytical studies of integral bridges, and the best thing i know of to answer your question is a publication from PCI: The State of the Art of Precast/Prestressed Integral Bridges. Covers all the bases, while very straightforward (<100 page). I got it for about $20 a couple years ago from pci, not sure how you might get it for less...

good luck!