Originally Posted by shaune
You are to research and produce an individual Engineering Report comparing and contrasting steel I beams and reinforced concrete beams for use in bridge construction.
-where are they used and why
Okay, well, in the spirit of making you do your own homework, I won't give you too much, but I'll try and guide your research some.
First, my assumptions. It sounds like you are comparing regular everyday highway bridges. Small span bridges. In other words, not cable-stayed bridges, suspension bridges, or other larger structures. We need to be talking apples to apples, or else this is pointless.
Second, your research will be easier if you use the correct terms. And going back to my assumptions, I assume you are comparing concrete versus steel GIRDERS.
So I am assuming that you are comparing steel girders (I-beams, as you described them) to similarly-shaped concrete girders. I also assume pre-stressed, since you mentioned fabrication? Are you excluding concrete box girders?
The Federal Highway Administration has plenty of examples/information you'll stumble across if you're using the correct google search terms. Here, for example, are design examples for a pre-stressed concrete girder bridge and a steel girder bridge.
As for the advantages of each. There are some engineering advantages of each, and maintenance differences, which you'll find when you google. But most of it is going to come down to cost. There are some environments where one may make more sense than the other, but there are fewer and fewer things that you can do with steel that you can't also do with concrete, and the lead-time for concrete girders is shorter.
Also, keep in mind your sources. If you read this, for example, don't forget that this is coming from a pro-steel group: http://www.shortspansteelbridges.org...eelBridges.pdf
You'll find stuff from concrete groups too.
Other things to think about comparing the two - span lengths (how far you can go without supporting piers), initial costs, life-cycle costs (including maintenance and repair costs), seismic considerations (if you live in earthquake country, which I don't), material availability (it can take a long time to get custom steel beams, especially in some areas), and constructability. If I were you, I'd google every one of those words.
That should be more than enough to go off of, plus what others have posted. Good luck! And remember how lucky you are to have the internet for research... when I was in high school, I would've had to find a local engineer to talk to and/or go to a library.
Last thing, your state department of transportation probably has a PDF Bridge Design Manual that might be good for you to look at also. Google it. Here's Colorado's, just as an example - http://www.coloradodot.info/library/...-design-manual
. There are plenty of direct steel vs. concrete comparisons, though, that you'll see when you google.