Bridge beams

I've seen bridges like that in the fabulous national parks in Utah. Very cool!

Brad, I think that you're going to need a company that has the tooling to bend a beam like that. If you are going to try it yourself, then you can cut a kerf every so often and then pull the things around a tree or something so the kerfs bend shut (all the cuts would be on one side) and then weld them up and grind them off (if cosmetics are that important). It will be very difficult indeed to keep the beam in one plane.

Why don't you look up "ironworker's union" in your local Yellow Pages and go down to their hall and just talk to some people?

Grant Erw> Hi there,

I am looking for someone in Minnesota that would be capable of bending square tube in an arch for bridges also. Anyone out there? Sven

Hi. There was an outfit that did really big pipe bends in Houston. I think they were on Old Spanish Trail. You might see if you can find them and give them a call. There are also some really big plate rollers for vessels in Houston as well. Of course, you're talking a radius much larger than these guys would normally do, but the length (35 ft.) doesn't seem excessive.

Good luck.

Pete Keillor

I beams are easily bent with just an oxy-acetylene torch with a rosebud and some water. You can easily do this yourself with minimal equipment. For further information check out some of the Linde books on oxy-acetylene equipment and usage. Ernie might be aware of this process as well. Perhaps some of the torch suppliers can give you guidance... Victor might have some info. It is a shrinking process. Very common many years ago. I have used the process in lots of ways... tightening braces, putting slight bends in all sorts of structural shapes.

Mark

Took a tour of the Chicago Bridge and Iron Works some yearr back and they certainly have the equipment to do bends like this. The fellow said they could roll bends in six inch thick HY 80, the stuff they made submarine hull out of, before they went to HY 100. That is

80,000 lbs yield strength!

They are located in Kankakee (sp?) Illinois so that is not too close to you but it is closer than Houston.

Errol Groff Instructor, Machine Tool Department H.H. Ellis Tech

613 Upper Maple Street Danielson, CT 06239

860 774 8511 x1811

Mid America Steel in Fargo, ND probably can do it, depending on the size of beam/tubing, and your check book! Greg

A 35 foot piece of beam cambered will be a fair chunk of change and it isn't what you really need. Shop around for ready made steel roof trusses. The 35 foot span is a stretch but two sections around eighteen feet is reasonable. You might even find some surplus sections of conveyor gallery that could be ganged together. Mines and sawmills often have this stuff laying around out back. Randy

Sorry if this is the wrong group to ask this question. A person in another group referred you guys to me.

My dad and I have a small piece of land in the thick forests and hills of east Texas and we have several trails in the woods for hikers, dirtbikers and 4-wheelers. We have built several small wooden bridges to cross small creeks in the past but now we want to build one that's a bit different.

We want to build an arched bridge with no supports underneath (just supported by the ground at both ends) - using two slightly curved metal beams to span a small creek. Then we will use 2x8 treated planks to finish out the bridge and we'll add hand rails too. We want to build this type of bridge because we really enjoy a similar type bridge here in the Dallas area that is on a bike path. We think this type of bridge will look really cool in the middle of the woods. It only needs to be able to support 2 or 3 four wheelers at a time. Cars and trucks can't physically get to it due to the trees and we'll make the bridge too narrow for them to fit on it anyway. It will need to be 35 foot long.

But finding where to have the two arched 35 foot metal beams made is proving difficult - mainly because we really don't know where to begin looking. A friend suggested that we should use steel 6-inch hollow square tubes. They would be strong and lightweight and we could drill into it to bolt the wooden planks and wooden rails to it. Sounds good, but who would we contact (in the Texas area in particular) to make these slightly arched "tubes" for us? I guess it would be cool if they could make them for us and then somehow cut them into 3 pieces so that we could transport them more easily. I guess they would need to have special plates welded to them at the joints so that when we bolted them back together they would retain their smooth curve and still remain strong at the joints.

Thanks for any hints on who to contact for this! Brad Stone

Huh? East Texas is generally south and east of Dallas, north of Houston. Kankakee is over 900 mi. north-northeast of Dallas. Houston is 240 mi. south of Dallas, and probably even closer to his place in East Texas.

Pete Keillor

Why don't you look for a wrecked/retired flatbed trailer (not a lowboy/gooseneck but a highboy trailer that is basically a 40+ foot long sheet with a pair of curved beams underneath. Just take the wheels off and rent a crane to lift it into place. You shouldn't have to do a great deal of site preparation (like bridge abutments) unless the banks are soft.

Just an idea from a guy who always looks for a way to use existing materials!

Jon

Good idea but it might be a problem getting it to the site without opening up an access route suitable for the cars and trucks he wants to exclude. Gerry :-)} London, Canada

Gerald Miller wrote: Good idea but it might be a problem getting it to the site without opening up an access route suitable for the cars and trucks he wants to exclude. ^^^^^^^^^^^^^ This is too good an idea to abandon that easily. If you can buy worn-out semi-trailers cheap enough, there might be enough money left over for a helicopter. 'cause, as others have pointed out, rolling curved beams ain't gone be cheap. Or, maybe the trailer could be turned on edge, with the wheels off, and brought in on a pair of forklifts.

On Sun, 24 Aug 2003 18:18:36 -0500, Brad Stone wrote: I was looking at your "needs", if you cannot haul "long" stuff out there , seems to me the best bet would be I-beams 3' or 4' , or as long as yoy could haul, (what ever you are using) ,,, that are 'made up' on each end so as to provide the arch, and bolt together. But that is going to be a lot of work,,,, I really like one "posters' idea of the trailer bed. If you could get a small farm tractor in the 'area', that you be ''''nice''''. My uncle, his son , and myself build a small bridge such as you describe,,,, but we are south of San Antonio, and 'oil field tubing' is cheap and strong, ,,, but we could '''get to the site''''' with a truck and trailer... We built it and then 'comealonged' it across the little water inlet, two or three days work if I recall correctly,,,, it is just below the Medina Dam. I hope some part of this,,,, is helpful. cl. "73"

Hey..neet... I build bridges.... The last one I made was 35 feet long... The easy way to make an arch bridge is to use small 3-4 foot peices and angle each one a few degrees... I used house trailer frames... I cross this bridge with my mule loaded with dirt... About 3000 lbs...

... ''''nice'''' ... ,,,, ... 'oil field tubing' ... ,,, ... ''' ... ''''' ... 'comealonged' ... ,,,, ... ,,,, ...

Oh, man - I'm getting a headache reading your post. Lighten up on the punctuation! :-)

a series of welds across bottom of beam, perpindictular to the length will bend a tubular beam. the closer the welds, the more it bends. the handrails can be incorperated into the superstructure.

I was thinking the same thing. By incorporating the handrails as part of the structure he can cut the size of the material considerably. It would take some serious engineering to get the sizes right and design the web bracing but the total weight would be a lot less. That would be a great advantage when it has to be hauled in and errected by volunteer human power. It would take some pretty healthy butressing at the corners though.

I would start by f> a series of welds across bottom of beam, perpindictular to the length will bend

The funny thing I see in all the responses so far is the total lack of engineering input. If your going to design facilities for public access you will need to be able to prove that they meet standards and where safe at the time of construction. I would look for a vendor that has previous experience with these sorts of bridges. You might even be able to buy a design off the shelf ( well out of a cad inventory).

In any event I'm surethat in Texas there will be places that can handle the beam design of your choice. The issue of getting that beam to the back country is a differrent story. If a suitable light weigth design is found you probally will find that a helicopter will end up being cost effective and probally safer. The only other reassonable option as some have suggested would be a sectioned beam that is bolted together in place. Sectioned beams are more work all around and thus more expensive.

Thanks Dave

The State of Wisconsin has a brochure on building "approved" recreational bridges for atv/snowmobile trails:

which is broken down into spans of over/under 40 feet if I recall correctly. They discuss loading, railings, foundations, etc. Seems like a pretty decent guideline. David

Look in the phone book under "Steel Fabricators". There are plenty of fab shops in Dallas, and I've done business with a few of them, just don't remember their names now. You will probably need some engineering done also. The fab shops should be familiar with civil engineers that can take care of this.

You might also consider Vulcraft, in Grapevine. They are a steel truss manufacturer. They once conjured up some bowstring trusses that spanned a large swimming pool here in Austin. They have in-house engineering. Don't know if they deal with the general public since they are usually a supplier to the steel fabricators. Gary Brady Austin, TX