Bridge Building/Concrete Work

[fensoncont.]

Hey guys,

I've learned dirt and utlities over the last year and a half, as well as learning a fair amount about paving and demo over the summer.

Next up for my education is concrete work and bridge building. The bridge building relates to an overpass for a highway, or a bridge for a river crossing. What goes into that? How is it done? What are some of the machines used during the process? I've heard things about Steel Piling, what is that in regard to bridge building?

As for concrete work, mainly flat work like big building pads (1.5 mil sf) at 1'
thick. Is that done utilizing a concrete paver, or laborers with concrete pumps? The next thing is tip up concrete walls. I saw a crane for a 1.4 mil. sf distribution center and it weighed 300 ton, took 12 lowboys to it on site. It was being used for the concrete walls, how is that work done? What are some more general costs for that type of work? How long does it take? How big of sections is this done in?

If you have any questions regarding my questions please ask, I'm not trying to have this done to an exact science yet, just get the basics down. Maybe figure out what machines to mobilize, or get an idea for general costs, as well as procedure.

I appreciate all the help I received on Heavy Equipment Forums prior to this.

 

[ForsytheBros.]

bridge building

Hi Fenson-
i'll take on bridge work best i can.


My limited experience is with bridges down in Texas, and i'll assume for conversation sake that the example bridge we're discussing is over another roadway, although a lot of the work is similar for most structures.

I'm basing my comments on what i've seen on a number of DOT designs, which rely on prestressed concrete beams.

1. Assuming survey control and staking is done, typically drilled shafts are constructed for interior bents and end abutments. Large drill rig drops shafts into earth a distance depending on point bearing requirements or skin friction. I've often seen a rough terrain crane nearby to help with tremmies for concrete or lowering reinforcing cages into the shafts.

2 Once shafts are constructed erection of column forms and abutments are built. Rough terrain crane is handy for column and reinforcing handling, as well as concrete bucket work to deliver mud to the new columns from trucks on the ground.

3. Interior bents (horizontal members on vertical columns) are then constructed after cure, taking into account bearing seats for prestressed beams.

4. Once interior bent caps are completed and abutments built, prestressed concrete beams are place on caps/abutments. Two cranes typically used to set beams , rough terrain crane used to set prestressed concrete panels on top of beams (panels typically serve as the bottom half of slab in this application) Panels are often "graded" on the beams to get elevation correct in anticipation for poured in place slab.

5. Concrete deck poured typically with large truss screed, and all the decks i've watched were pumped. Screed must be "graded" to allow for deflections of the spans while screed/wet concrete are in play, so final deck falls out to the correct elevation.

6. Some decks were formerly finished via tining during concrete placement. I'm not 100% sure of the DOT spec now, but i think they may be using sawing to accomplish the grooving in the deck these days.

7 Any outside barrier rails often handled with a slipform paver.

I'm leaving out a bunch of details , but hope this gives and "overall picture"
thanks

 

[fensoncont.]

I appreciate the help, I understand the big picture of bridge building. There's just one spot where I am getting somewhat confused. This is the steel beams that go far down on the earth, and then the concrete pillars.

Other than that I understand the steel beams that lay across from the bridge, in which pre cast concrete is placed, then cast in place on top of that. As well as the side concrete pices, which are done using slip form pavers.

 

[JDOFMEMI]

Nolan

Try this link to one of the largest bridge projects underway in SoCal.

Lots of good pics there so you can follow the progress



http://www.dot.ca.gov/dist8/projects/riverside/6091215/index.htm

 

[Tanstaafl]

Bridges are very, very interesting creatures. There are so many different sizes, types and conditions that each one for the most part has some special challenge.

A site that pretty well details the construction of a bridge is The Iowa River Bridge. This bridge is fairly unique as it was the first launched girder bridge in the U.S. Meaning that they assembled the girders on one side and then pushed them all the way across to the other side. The site had some major environmental issues to deal with so this is the solution that they came up with. If you dig around in the pictures at that site, it will give you a very good feeling for what goes on.

Next up for my education is concrete work and bridge building. The bridge building relates to an overpass for a highway, or a bridge for a river crossing. What goes into that? How is it done? What are some of the machines used during the process? I've heard things about Steel Piling, what is that in regard to bridge building?

Forsy pretty much nailed down the construction order. The one big thing is that not all places use drilled shafts. A lot of places use driven steel or concrete piles for support depending on what type of soil is onsite and how close rock is to the surface.

As fas as steel piling goes, you generally see two types. There is sheetpile, which is a thinner wall item that is normally temporary and is used for retaining walls, cofferdams and items such as that. Generally speaking they use a vibrator or a hammer and put it into the the ground where they need it and then remove it once they are done. Then you have H-Piles. These are permanent and are driven into the ground with either a hammer or vibrator also. These are used to transfer all the weight of the bridge into the ground. Piles Can be anywhere from 30'-100'+ long depending on the loads and how strong the soil is.

As far as machinery goes you can see just about anything on bridge sites. Excavators, cranes, skid steers, pump trucks, scrapers, dozers, graders, barges, pile driving rigs, drill rigs, sweepers, rollers, pavers, you name it, and it's probably been on a bridge site. It all depends on the site. Replacing a bridge in a semi urban area? Probably not going to see scrapers or lots of large earthmoving equipment. Need to convert an at grade crossing to grade separated in a rural area? You'll be seeing a lot of dirt coming in to get things in place.

As for concrete work, mainly flat work like big building pads (1.5 mil sf) at 1'
thick. Is that done utilizing a concrete paver, or laborers with concrete pumps?

Never dealt with big building pads (especially at that size). I'd imagine that for something that big they'd probably use a paver somehow. Just seems extremely difficult to try and place that much by hand, especially at that thickness. I did some concrete testing for a new grocery store and they line pumped the floor when I was there. Simply left 2 of the tilt up panels off the side of the building and they simply drove the pump right inside the place and backed the trucks right up to it.

The next thing is tip up concrete walls. I saw a crane for a 1.4 mil. sf distribution center and it weighed 300 ton, took 12 lowboys to it on site. It was being used for the concrete walls, how is that work done? What are some more general costs for that type of work? How long does it take? How big of sections is this done in?

Are you asking how is it all assembled or how do they actually produce them?

For producing most of it is done off site at a precast plant and then simply trucked in. Some stuff like that can be cast on site and then tipped up, but it's only in extreme situations, not to mention difficult and very expensive. As fas as section size goes, I'd guess that they come in either 10' widths (easier to transport) and no longer than 40' feet (again a transport issue) or smaller sizes. Just a guess though.


As far as assembly I don't know a ton but know of two general ways.
-Method 1 is kinda like putting up the sheathing on a house. You erect a steel frame, and then simply secure the panels to the frame and then tie them into each other for added stability.
-Method 2 is kinda like a big thing of legos. You basically stack them all together and use weld plates and grout keys to tie the entire thing together.

Think I answered most of your questions. That or confused you even more.

 

[digger242j]

Tanstaafl, that was a pretty impressive first post. :thumbsup

Welcome to Heavy Equipment Forums!

 

[Countryboy]

Welcome to Heavy Equipment Forums Tanstaafl! :drinkup

 

[Lashlander]

Heres a pic on a building expansion we did a few years ago. On this job we were able to reuse 3 large sections of the old wall. This section weighs 95,000 lbs. We pulled them out of the old wall, spun them around and walked them behind us and reset them. The rest of the walls were tip ups poured on the ground. They poured them four high one on top of the other. We set up the crane parallel to the foundation, reached inside the foundation picked them up and then walked them into place. This crane weighs 150 ton and takes 6 trucks to move it with 120" of boom. This is the only picture of this job. I was running the crane and my wife took this picture. We did a tip up wall last year for the Coast Guard and the inspector gave me a disc of the job from start to finish. If you like I'll see if I can find it and post some pics. Tip ups are a little different in this area because its an active fault zone and we have around 5 or 6 earthquakes a year.

 

[bjl14]

are you referring to h-piles when you say steel beams into the ground? there are stringent requirements for bridge work, it's not just like moving dirt. the deck pour has to be carefully planned and isn't like pouring a slab on grade. even the smallest bridge is a highly engineered structure compared to earthwork and paving. are you looking to get into bridgework at your company?

 

[Countryboy]

Welcome to Heavy Equipment Forums bjl14! :drinkup

 

[fensoncont.]

Thanks for the post, but as you can see I'm a COPAA member which means I'm 15. I joined the forum when I was 15, I'm just trying to further my education into bridge work. When I said steel piles in the ground I was referring to H Piles or Concrete Piles.

 

[bjl14]

Oh wow, 15, you're sure gonna have some knowledge some day. You going to go to college or join a union or what? I was busy screwing off when I was 15. Piles can be done many ways. Bridge work most always has h-piles, whether they're driven or drilled. Sometimes they'll drill (auger drill, backed out with grout to resist cave in) if the area is busy or people don't want to hear the noise from driving pile. I was on a job once where we drilled over a hundred h-piles and let me tell you, it's no easier than driving. It's rare to do, but some bridges are founded on caissons, which have become very popular for buildings. I've done buildings on caissons and in my opinion they're a much bigger headache than piles. Driving or drilling piles is tough until you get your angle, then it's hammer ahead. Caissons can be up to 8 feet in diameter sometimes, and when you get in rock, you'll spend hours drilling. Then you've got to get your casing in before you make your pour, then get it back out once the concrete has set up. The biggest ***** is getting the rebar cage in. Most of the time it's within a tight tolerance, so error is not an option. I was on a job once where our caisson contractor gave up three casings because we were below the water table (Pittsburgh is so fun) and the water was making the soil pressure unbearable. They made their pour and the frictional forces in the soil outside the casing were so huge that their rig couldn't pull the casing back out. I could've sworn it was their first caisson job, they seemed to have no clue.

 

[fensoncont.]

Thanks for the information, there's one last final thing I want to clear up. I currently have prints to the US 24 Bypass in Northwest Ohio, it has 5.5 miles of new 4 lane divided highway with 8 overheads and about 1.7 mil. CY of earthwork on it. The estimated cost is $57,600,000, the prints are near 850 pages long!! I've got a little over a month and a half to have my bid done for letting day. Enough for the project itself, but anyhow in it the piling is all driven to rock or friction which was spoken of earlier.

I have also heard where they will drill a shaft, a rebar cage will then be dropped down into the shaft and concrete will be poured into it, which is called a 'caisson' Are caissons ever on bridges, or are these generally utilized on large building foundations?

Thanks for your help!!

 

[928G Boy]

Caissons are definitely used for bridges sometimes as well.

 

[fensoncont.]

Alright, just what the civil engineer calls for, I'll watch out for it.

 

[fensoncont.]

Is there anyone that would be able to help me with a general idea of material prices for the bridge work? One of the main things is the furnishing of the concrete/steel piles. As well as the Epoxy Coated Reinforcing Steel. Last but not least the girders.

 

[928G Boy]

I'm assuming those are precast girders you're talking about... I have no idea what suppliers you guys have out in Ohio, but out here for precast girders I'd probably definitely go to Lafarge first.

 

[fensoncont.]

Your correct, I guess I could look to some old bid tabs and see if I could find something but that cost will include labor as well.

 

[fensoncont.]

Does anyone know weights of girders and piles? If I were to give lengths, material, and diameter etc. to help me with determining a crane size?

 

[Tanstaafl]

Hmmm, well Steel H-Piles are all of predetermined size for the most part. A couple of numbers that stick in my head are 114, 97, 82, and 75 lbs/ft. I think there are 9 different "normal" H-pile sizes in total.

For pre-cast concrete piles generally speaking they are cast in 6" increments (sq and round). Figure out the cubic footage in a given pile and multiply by 150 lbs/c.f. A 1' long 24" square concrete pile has 4 C.F. of concrete per linear foot so it's weight could be approximated at 600lbs per foot.

There are so many different types of girders and different configurations that it's nearly impossible to tell the weight without a set of plans. Most plans will somewhere show a cross section of the girder and list an area somewhere so you could convert that into a volume and then get an approximate weight. Also, most State DOTs have their own specific section designs that they use. Of course, they then have special sections for extreme cases or when the standard ones don't fit or can't deal with the loading.

Hope that helps.