Concrete/Steel Girder Question

[fensoncont.]

Hey guys,

I was just wondering if anyone could steer me in the right direction for approximate weights of steel and concrete girders. I'm talking I Beam Girders to see beneath the deck on a bridge. I'm trying to do some calculations on crane requirements for setting these in place. All help is appreciated.

 

[AtlasRob]

Hey guys,

I was just wondering if anyone could steer me in the right direction for approximate weights of steel and concrete girders. I'm talking I Beam Girders to see beneath the deck on a bridge. I'm trying to do some calculations on crane requirements for setting these in place. All help is appreciated.

The thing I really like about this forum is I know you are going to get serious answers to this question that I will also appreciate. :thumbsup
I have never been involved with estimating or pricing jobs and I am always fasinated by the questions you ask. :drinkup

 

[dirt digger]

concrete weighs 150 pounds per cubic foot...for reinforced standard weight concrete...you would have to do the calculations as far as geometry goes to find the actual weight but 150 pcf is what we always use to design concrete structures

and your typical 36" web with a 12" flange I-Girder weighs roughly 142 pounds per foot...(100 foot girder would weigh 14,300 lbs)

or if you don't have that size girder then you can use the fact that most structural steels weigh 490 pounds per CUBIC foot

 

[digger242j]

I can't speak for the type of beams that are used in bridges, (if in fact they're different, although I suspect they're the same), but for what's used in the residential construction I work on, the specification for the beam tells you the weight. They do come in different weights for the same dimension of beam. For instance, the plan that just happens to be sitting here next to my computer calls out several W10 X 27 beams. That's shorthand for a 10" tall, wide flange beam, that weighs 27 lbs/linear foot. A W10 X 45 would weigh 45 lbs/foot, but would obviously be stronger. If you know the length, you can figure out the total weight.

Here, I googled up a table for you:http://www.engineeringtoolbox.com/american-wide-flange-steel-beams-d_1319.html

 

[Tanstaafl]

concrete weighs 150 pounds per cubic foot...for reinforced standard weight concrete...you would have to do the calculations as far as geometry goes to find the actual weight but 150 pcf is what we always use to design concrete structures

and your typical 36" web with a 12" flange I-Girder weighs roughly 142 pounds per foot...(100 foot girder would weigh 14,300 lbs)

or if you don't have that size girder then you can use the fact that most structural steels weigh 490 pounds per CUBIC foot

Hit the nail on the head.

Concrete girders you are pretty much going to have calculate the weight as each DOT uses different designs of girders. Somewhere in the plans it might show an area for the girder (normally in sq. inches). Divide that by 144 to get sq. ft and take it times 150 pcf to get your weight per foot.

As far as steel goes, unless you have a small enough bridge to be using rolled shapes, you are going to have to run the math also. Most steel girder bridges are made up of welded plate. As the depths they need vary considerably and rolling them just isn't an option. Figure out the area (in sq ft) and take it times 490 pcf. That'll give you a weight per foot and then just take it times the length of the girder to get you total weight.

 

[dirt digger]

Tanstaafl do we have another CE in the house???

 

[Northart]

Steel Reference Source

Here's another valuable source for structural steel .

" Manual of Steel Contruction "

by American Institute of Steel Construction.

 

[joispoi]

The weight of the steel should be the last # in the spec for what they´re calling the beam. That figure is the # of pounds per foot. This was my experience with light beams in residential construction. I believe the same should hold true on a larger scale.

With that said, your safest bet would be to get in contact with the material supplier(s) to get exact figures, preferably in writing (cover your ass).

 

[Tanstaafl]

Tanstaafl do we have another CE in the house???

How could you tell? Yeah, I graduated in Dec '07 from Iowa State.

 

[dirt digger]

i'm on your heals...i graduate next June...actually just about to start finals week right now...i have been studying fluid mechanics and materials all day...came on here for a little break

how have you found the job market to be?...here at PSU we have had 100% job placement the last 3 years, i really hope this possible "recession" doesn't screw me over next year

 

[Turbo21835]

Dirt Digger, its going to be tough for a little while. That being said, I dont think we are too far off from a lot of major public infrastructure projects coming. We are watching our roads, bridges, sewer and water systems crumble before our eyes. The people in Washington are just now starting to see this. The I-35 bridge collapse was a real eye opener for most. What a lot of people don't realize how a lot of sewer and water systems are in the same shape. My home town still has thousands of miles of lead water pipe. Not to mention with lots of miles of 100 year old concrete and iron pipe. As i said, things are slow now, but a few years down the line, things will be picking up big time

 

[dirt digger]

I am really not too worried about it...in fact I have turned down more internships then I can count...I actually have companies calling me rather then the other way around

I have a lot of friends in other engineering fields (electrical, aerospace, mechanical, chemical) and they were lucky to get the jobs they have...they get pretty pissed when i tell them i had to turn another internship down...haha, they just make me buy the beers


they say Civil Engineers were the first and will always be some of the most important engineers out there...i mean if you look at it, if it wasn't for us how do the other engineers get to work? haha

 

[Tanstaafl]

i'm on your heals...i graduate next June...actually just about to start finals week right now...i have been studying fluid mechanics and materials all day...came on here for a little break

how have you found the job market to be?...here at PSU we have had 100% job placement the last 3 years, i really hope this possible "recession" doesn't screw me over next year

Definetly do not miss finals. Or fluid mechanics. You picking an emphasis or just going with general?

As far as jobs, I'm still looking, but I screwed up(Really thought I was going to get a position with the firm I had an internship with, and I didn't find out I wasn't getting a spot until late November, so I was way behind the curve). So I'm living at home. I'm waiting to hear back from a phone interview that felt like it went really well.

The market is getting a little tighter I think (not horrendously though). If you've got experience and can sell yourself well you shouldn't have a problem. My advice would be to apply early and often. I think out of my graduating class of ~30-40 maybe 3-4 of us didn't have a job, and two of them found jobs the the start of '08.

 

[dirt digger]

my emphasis will be more toward the water resource/environmental side...storm water work and things of that nature...i am shying away from structures because that is not where my background comes from...i have been working on dirt jobs involving drainage and environmental things since the age of 15 and love working with it, so i am continuing on that track

 

[digger242j]

I have a lot of friends in other engineering fields (electrical, aerospace, mechanical, chemical) and they were lucky to get the jobs they have...they get pretty pissed when i tell them i had to turn another internship down...haha, they just make me buy the beers


they say Civil Engineers were the first and will always be some of the most important engineers out there...i mean if you look at it, if it wasn't for us how do the other engineers get to work? haha

They also say, "Mechanical, electrical, and aerospace engineers build weapons systems. Civil engineers build targets..." :cool2

 

[dirt digger]

then we get to go back in and rebuild them...talk about job security:usa

 

[ForsytheBros.]

hi fenson-

you might consider checking:

www.dot.state.tx.us

this is the txdot web page. You can browse through business section i think to download cad (microstation format) files (or pdfs, if i remember correctly). Should have stds for aashto conc beam dimensions/geometry. Seems like a Ty IV conc beam was maybe 800lbs/lf (or was it 521 lbs/ft, arrggghh, cant remember), although my memory is sketchy, at best.....

 

[fensoncont.]

Thanks for the help everyone, I really appreciate it.