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Any structural engineers around?

G

Garvey

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May 1, 2010
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Melissa, Texas
One is actually a 10" X 8" wide flange I-Beam. The other is I-Beam 10" X 5" 24 pound. North side will be on land 8'. South side will be on land 4'. 40' long beams. So 28 feet free span. I trussed one so far. That is 2 7/8" O.D. (2 1/2" pipe 3/16" wall) The beams will be spaced 6' apart, because that is centers of tractor tires. Gonna cross these beams with more pipe for a total of 12' wide. Saddle the ends, weld in pipe (like a top rail on its side) and then truss that as well. Probably deck it with milled utility poles. So the bridge is going to get some more dead load on it. Bout 12,000 pounds is the heaviest live load going across it, but let's call it 15,000.

Built enough? Under built?

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I barely made out you're trying to build a bridge.
Barely.
I think *maybe* things might become more clear if you draw up a draft of what you're trying to do ???

Truss up, truss down ?
Ground type ?
Exact thickness of beams (not exactly standardized stuff....US made or ??).
It looks like that closer beam has been butt welded ? That will be impossible to design for....you need plates on both sides of that, and probably 1 foot overhang on each end so 2 foot long plates.
At 28 foot span you'll be needing a few pilings footed in concrete.
Rainfall, flooding ?
 
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Truss down. The horizontal pipe will be in tension. The I-beams were part of a county road bridge that was replaced. Those joints do have fish plates on both sides. 1/4" web 5/16" flange, 10" depth, 4 5/8" wide flange. The lighter of the two beams.

The creek it's crossing has water in it right now. Really trying to avoid any columns in the creek. Yes the creek can fill up, which is 12 feet deep. Thus the reason for avoiding columns in the creek.

I will box in the beams that cross, with more I-beam. So a long, narrow rectangle. I rented a post driver a few weeks ago and drove 2 7/8" O.D. pipe 8 feet in the ground where the ends of these beams will be, and weld the beams to the pipe in the ground. So four of those. Just to keep the bridge from shifting.
 
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Just an FYI is this creek out in a field, by a road what?

Army corp of engineers are pretty crazy about people doing stuff like this.
They have survey planes that watch for stuff like this.
Say you build this and it floats off and damns the creek up now what?
 
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Under built. Probably hold a golf cart alright, pickup maybe, 12k lb tractor I doubt it. You are going to have to much dead load already on the beams before you start adding your live load. But I don't know anything about this kind of thing.
 
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Ravenworks said:
Just an FYI is this creek out in a field, by a road what?

Army corp of engineers are pretty crazy about people doing stuff like this.
They have survey planes that watch for stuff like this.
Say you build this and it floats off and damns the creek up now what?
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Pretty much the center of my land, 70 acres. Bout 400 yards away from a public road.
 
Better off to get a cement culvert.
bcIowa1.png


I'm a pipelayer by trade. But I've been involved in major infrastructure development in WA. Lots of bridges and over passes. All the shit on I5 outside McCord and Ft. Lewis I had a hand in. Same with by tacoma dome and a bunch of stuff in Seattle.

28 foot span is a lot to not have columns. If your not sinking columns, making footings or abutments your bridge will need to be redesigned.

While it may work. As posted above Army engineers would shut it down if found out. Also with no abutments and just some 8 foot poles sunk in the ground you don't have much to prevent washouts.

Probably better off to just get a 53 foot flatbed trailer and set that sucker over there.
 
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I’m going to say under built by quite a bit. A w8x20 is what I would call barely adequate to hold up just a roof with that span.

I do a bunch of structural welding and on the last 2 buildings I put up, with a 26’ span, both used w14x22 for the beams bearing only the roof trusses.

For the 2nd level with a 4” concrete slab and 1.5c decking 40’x18’ area, the beams with the trusses bearing on them were w16x31 which would be around 30k lbs with people on it plus a pretty large safety factor.

With a w8x24 beam with 10k point load in the center you are going to get 3” of deflection, which is a lot.

Also, is that truss welded with flux core? What size machine? I see a lot of start and stops on the welds. Also I see the rust was not ground off before it was welded. I don’t see fish plates on the butt welds. Were they 100% penetration? Will they shoot xray?

Honestly I would take it to the scrap yard and have the whole bridge engineered and use the correct speced beams.
 
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Found some plans of bridge I bid a while back. 49’ span, columns at 18’ off each side, beam spec was w12x72 on each side
 
TxWelder35 said:
I’m going to say under built by quite a bit. A w8x20 is what I would call barely adequate to hold up just a roof with that span.

I do a bunch of structural welding and on the last 2 buildings I put up, with a 26’ span, both used w14x22 for the beams bearing only the roof trusses.

For the 2nd level with a 4” concrete slab and 1.5c decking 40’x18’ area, the beams with the trusses bearing on them were w16x31 which would be around 30k lbs with people on it plus a pretty large safety factor.

With a w8x24 beam with 10k point load in the center you are going to get 3” of deflection, which is a lot.

Also, is that truss welded with flux core? What size machine? I see a lot of start and stops on the welds. Also I see the rust was not ground off before it was welded. I don’t see fish plates on the butt welds. Were they 100% penetration? Will they shoot xray?

Honestly I would take it to the scrap yard and have the whole bridge engineered and use the correct speced beams.
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5/32" E-6011 off a Miller Syncrowave. Had it set at 90 amps. All steel has been cleaned prior to welding. On the I-beam, grinding wheel, then a cup brush. Pipe, just brushed at the bench grinder before install.

The south bank slopes not too aggressively. The north bank is a shear wall. On the south bank I can add more columns and reduce the Free span to 19 feet.

Think I will add some triangles to the truss. Was the original plan anyway.
 
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DarnYankeeUSMC said:
I am in the HVAC business. So I know. But it is a good slogan to sell their product.
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Me too. Was a Trane strategic partner for years and even got made a Kentucky Col. for helping with their project Steeplechase (re-design of their climate changer air handler product) which built a new factory in Kentucky. But the last few years their stuff has gone downhill.
 
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Garvey said:
5/32" E-6011 off a Miller Syncrowave. Had it set at 90 amps. All steel has been cleaned prior to welding. On the I-beam, grinding wheel, then a cup brush. Pipe, just brushed at the bench grinder before install.

The south bank slopes not too aggressively. The north bank is a shear wall. On the south bank I can add more columns and reduce the Free span to 19 feet.

Think I will add some triangles to the truss. Was the original plan anyway.
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So you used a non structural rod set 50 amps too low with multiple start/stops.

I can already see how the video plays out. Tractor drives across it, beam starts to deflect, welds start popping like popcorn, beam deflects more then fails completely, tractor is in the river. You have to call a crane out to come get it out, alphabet soup shows up, you scramble to hide the welder and say it was like that when you moved in.

Please have a camera rolling when you drive over this for the first time.
 
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Yeah this is a terrible idea as currently shown. At minimum you should use one continuous beam the entire length of the span. Welding two different beam profiles together makes a crazy weak point that will break. I would recommend using the right beam for the job, any welding on a structural beam alters its properties. It can be done if the right considerations are taken, but that is beyond internet advice levels. If you don't know what you are doing, it is worth paying someone that does to not end up injured or dead.
 
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TxWelder35 said:
So you used a non structural rod set 50 amps too low with multiple start/stops.

I can already see how the video plays out. Tractor drives across it, beam starts to deflect, welds start popping like popcorn, beam deflects more then fails completely, tractor is in the river. You have to call a crane out to come get it out, alphabet soup shows up, you scramble to hide the welder and say it was like that when you moved in.

Please have a camera rolling when you drive over this for the first time.
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Can clean and go back over them with an E-7018.
 
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Garvey said:
Can clean and go back over them with an E-7018.
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You mean take it to the scrap yard and start over with the correct beam size.

You can’t just go over the top of some cold ass 6011 and hope for the best.

You are going to end up turning your tractor into a submarine and it seems their is nothing we can do to keep you from going through with the transvvehicle surgery so you just do you boo boo.
 
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Mech. engineer here but was a metallurgy minor and an ASME certified nuclear welding inspector. Not a civil engineer so don't know shit about bridge approach aprons but IMO you are going to regret this deeply. A basic "strength of materials" textbook would tell you that. As someone stated above, I'd try to find a retired railroad car flat bead. I worked part of my way through college as a welder building them and they are hell for stout. At least back in the day they used to be because we had railroad inspectors looking over our shoulder all the time. The center sill of a flatbed is basically a structural beam and the wheel truck supports would maybe make good anchoring points for concrete pylons.
But also as stated before the COE or some state agency will have your ass if you don't get permits for an approved design.
I know it sucks but I've had to deal with COE people over the course of my career nan about 90% of them don't know shit about what they're "in charge" of. They're mostly asshole bureaucrats.
 
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Have a 32' tandem dual trailer. Gooese neck to axle centers is 24'.

14" I-beam, slightly trussed under the bottom flange. Pretty standard design with shorts of 3" channel flange welded to beam flange, and the bottom merely finished off with flat bar. Those trailers carry 12,000 pound tractors every day.
 
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Garvey said:
Have a 32' tandem dual trailer. Gooese neck to axle centers is 24'.

14" I-beam, slightly trussed under the bottom flange. Pretty standard design with shorts of 3" channel flange welded to beam flange, and the bottom merely finished off with flat bar. Those trailers carry 12,000 pound tractors every day.
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And you are using a beam almost half the size, over a larger span. Not sure what you are trying to prove here
 
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Garvey said:
Have a 32' tandem dual trailer. Gooese neck to axle centers is 24'.

14" I-beam, slightly trussed under the bottom flange. Pretty standard design with shorts of 3" channel flange welded to beam flange, and the bottom merely finished off with flat bar. Those trailers carry 12,000 pound tractors every day.
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Yep that's correct. Don't forget the video.
 
TxWelder35 said:
You mean take it to the scrap yard and start over with the correct beam size.

You can’t just go over the top of some cold ass 6011 and hope for the best.

You are going to end up turning your tractor into a submarine and it seems their is nothing we can do to keep you from going through with the transvvehicle surgery so you just do you boo boo.
Click to expand...

Man, I don't know what you mean about cold. I've got 2/0 lead on that machine. The welds penetrated and filled. Any hotter and they would not have filled.
 
TxWelder35 said:
And you are using a beam almost half the size, over a larger span. Not sure what you are trying to prove here
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Not trying to prove anything. Using what I have. Make a 10" beam into a 20" trussed beam, using all materials I already have. Just have to put time into it. The truss isn't done. When it's done there's nothing wrong with a truss. They do work every day.
 
Garvey said:
Man, I don't know what you mean about cold. I've got 2/0 lead on that machine. The welds penetrated and filled. Any hotter and they would not have filled.
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90 amps is 40 amps too cold for a 5/32 rod. Doesn’t matter what size lead you have. For a 5/32 you should have been around the 130 amp range minimum, preferably 140.

6011 is not a structural rod and it’s properties are not conducive to structural applications for reasons that go over your head.
 
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I would take this all as no one wants you fuck up and get hurt or get sued/fined till your bankrupt.

I'm not a fan of permits for private land. But when you cross certain thresholds on job size. If your making a 2 story hunting shack, who cares.

This is a structural design intended to hold alot of weight . Needs to be designed as such.
 
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Garvey said:
Not trying to prove anything. Using what I have. Make a 10" beam into a 20" trussed beam, using all materials I already have. Just have to put time into it. The truss isn't done. When it's done there's nothing wrong with a truss. They do work every day.
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Trussed beams are fine if you know how to make sure you are safe. You do not, which is why you are on here asking. I get that you are trying to make what you have work, but it will not safely. Trade or sell what you have and either get bigger beams or some have suggested finding a semi trailer. The correct beams for this project would be W12 or W14, north of 60 lbs per foot on both sides, assuming you have a solid base to set these on at each end (ie reinforced concrete that is also the right thickness). You have moved way beyond hobby level bridge building at this point.
 
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camocorvette said:
I would take this all as no one wants you fuck up and get hurt or get sued/fined till your bankrupt.

I'm not a fan of permits for private land. But when you cross certain thresholds on job size. If your making a 2 story hunting shack, who cares.

This is a structural design intended to hold alot of weight . Needs to be designed as such.
Click to expand...
This, I’m not trying to be a Debbie downer but this path does not end well.

Also, you need to design your bridge for much more than what just you plan on using it for. For example, one residental bridge I bid, on private property, had to be built strong enough to get an emergency equipment across it. Will your design hold a fire truck plumb full of water?

There is way more to this than you are thinking about, and is way beyond your capabilities and understanding. As a professional welder that does this everyday, there is not a chance in hell I would design my own bridge to span 28’ over a river. I’m calling an engineering firm to spec the bridge for me.
 
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TxWelder35 said:
This, I’m not trying to be a Debbie downer but this path does not end well.

Also, you need to design your bridge for much more than what just you plan on using it for. For example, one residental bridge I bid, on private property, had to be built strong enough to get an emergency equipment across it. Will your design hold a fire truck plumb full of water?

There is way more to this than you are thinking about, and is way beyond your capabilities and understanding. As a professional welder that does this everyday, there is not a chance in hell I would design my own bridge to span 28’ over a river. I’m calling an engineering firm to spec the bridge for me.
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Doesn't need to hold a fire engine or truck. My driveway comes from the county road, crossing no body of water. This is to go from north pasture to south pasture, for my own usage, and no one else.

So, bottom line, no one has pointed me to that engineer I brought up and so have you. Of course I'll pay the man for his time and expertise.

As I said before, these very beams used to be a bridge on a public county road. Thought I do not know the span they were previously making.

Many of yall would stroke out seeing some county road bridges around my place. They span creeks just like mine. Are built only out of cross ties, and tractor trailers cross them loaded with corn and wheat.
 
I'm going to simply throw out a bit of information here. It can be read or skipped over. It can be heeded or ignored. This information was gleaned from one of the designers of (what we called) the Annacis Island Bridge but was officially named the Alex Fraser Bridge. It was/is an arced suspension bridge, to-which the majority of suspension bridges built since the late 80's around the world mirror it's design.

There's so much MORE to it, but here's the short version:

The towers and cables that the bridge is suspended on, only hold/carry the load of the weight of the bridge itself.
(read that again)

It is the roadbed at each end of the bridge that absorbs and supports the weight of the mass (vehicles) ON the bridge that needs to be structured and reinforced. As mass moves along the bridge, (shaped like an arch) it is the bridge approaches that take the load.

(read that again, twice)

Look at any empty flat-deck trailer. Especially the newer lightweight aluminum ones. There's quite an 'arch' to them, right? But when it is loaded down, that arch flattens out somewhat. You don't want to get that to 'sagging'.

Same principle for the bridge span. I'm not suggesting that you build an 'arch bridge'. What I AM suggesting to you though, is to seriously consider where your stresses are, and where your compressions are, to therefore design your load-bearing features properly.

Or, as quoted by the co-pilot in the alien craft in Independence Day..... "No More OOPS..."
 
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I doubt an actual engineer will comment on it for liability reasons other than to say don't do it. A couple folks have mentioned rail cars. They're often used temporary bridges during pipeline construction and carry heavy equipment loads when setup right. They're also sometimes used for low-cost bridge construction/replacement on low-traffic rural roads. Certainly understand wanting to use what you already have but it might be worth putting the word out in your local area that you're interested in one. Also check w/ any pipeline construction firms that might be close. I've seen them stockpiled on storage yards and even occasionally given away/sold for scrap.
 
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To the OP. it seems as if almost every serious reply says your design won't work. In my area a farmer cleared his ditches for his own property and the Enviro idiots fined the crap out of him for distrubing "wetlands".

If you don't want to listen to the guys posting, then why ask at all? If that's the case and all you wanted was a rubber stamp of your project, then go ahead.
 
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tomcatmv said:
Me too. Was a Trane strategic partner for years and even got made a Kentucky Col. for helping with their project Steeplechase (re-design of their climate changer air handler product) which built a new factory in Kentucky. But the last few years their stuff has gone downhill.
Click to expand...
Same here, been a dealer for 25 years. There equipment is shit and we are changing brands. The newer dual wall climate changer air handlers aren’t bad. We’ve always used a lot of Carrier on our Commerical side and looking at switching to them for residential.
 
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That picture of them using a culvert is another BAD idea.
No head wall, damned up with debris and you'll flood people.

If it were me I'd ramp each side out with a hoe and be done with it.
 
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