Building a bridge

[whiskyb]

I have a small creek on my property that I would like to store my 5th wheel trailer on the other side. The span would be about 8-10' I was wondering what it would take to support the weight of a 30' 5th wheel camper and my Ford F350 dually to be able to safely cross it.

I wandered around my local scrap metal vendor the other day and was able to locate 8 and 10" I-beams

My thinking was to use maybe 4 of these and plank it with rough cut 2" boards.

Anyone have any suggestions

[fred cook]

Are you wanting a clear span or would you be willing to build in a mid span support? As an alternative to putting something in the water, you could brace from each side headwall up to the center of the span so that some of the load would be transferred (via force vectors) to the ground but leaving the stream free and clear. Also, I would tie the side beams together with steel to help stabilize the assembly. Your truck/trailer assembly will weigh probably around 15,000 lbs but the weight will be distributed thru the two truck axles and the trailer axles. Figure on about 10,000 lbs max point load (trailer). Considering the cost of your camping rig, it might be worth the price of getting someone to do the math and tell you what beam sizes you will need. Good luck with your project.

[kach22i]

Expect to pay somewhere between $100-150 dollars an hour for a structural engineer.

Make sure all your work does not wash away in a flash flood. Do you have any information on that creek?

[Seahawk]

Originally Posted by kach22i

Make sure all your work does not wash away in a flash flood. Do you have any information on that creek?

Pics would help as well. I have done this using culverts.

[whiskyb]

I'll take a few pics this afternoon

[IROC]

A W10x30 A36 beam with a 10 foot, simply supported span will support a center load of 19440lbs with a factor of safety of 2 on the yield strength.

For what that's worth.

When you say "I" beam, do you mean "S" or "W"? An S10x25.4 would hold 14820 lbs in the above example.

[whiskyb]

Not sure the actual designation of the beam. They were at a scrap yard. 8-10" does sound like it might work. It has stopped snow/raining so I will go take a few pics now

[IROC]

Originally Posted by whiskyb

Not sure the actual designation of the beam. They were at a scrap yard. 8-10" does sound like it might work. It has stopped snow/raining so I will go take a few pics now

There are essentially two types of beams - "W" beams or "wide flange beams" and "S" beams which are commonly referred to as "I beams". An "S10x25.4" beam, for example is a "S" beam that is 10" tall and weighs 25.4 lbs/ft. Simply taking some measurements of the beam height and the width/thickness of the flanges and webs will allow you to determine what it is...

[vash]

if you take some dimensions of the beam,someone can go thru the steel manual and probably estimate the exact beam. from there, the calcs are pretty vanilla. the trick will be to pour some kind of slab at the ends..(we call them abutments) to anchor and support the ends. you typically anchor only one end, and allow the other to slide.

10" is nothing. i wouldnt support from mid span. running water puts crazy loads on columns. the added math wouldnt be worth spanning such a short distance. cool thing about the dually and trailer, you wont be able to put them both on the bridge at one time, so the loading is relatively light.

talking out of my butt here, i bet a simple 12x12 wood corbel bridge would hold up your dually. what does the trailer weigh? a camping trailer? less than the dually?

[Rusty Heap]

Calvin and Hobbes Dad explains it best in the first cartoon...........

Man I miss that 'strip, words of wisdom I tell yah:


Calvin and Hobbes Dad explains science | s-anand.net

[looneybin]

get an old flat bed truck trailer & place it on concrete abutments.
If the span is longer, you could use an old railroad flatcar.
they can handle the load easily, all you have to do is crane it into position

[Zeke]

Originally Posted by vash

if you take some dimensions of the beam,someone can go thru the steel manual and probably estimate the exact beam. from there, the calcs are pretty vanilla. the trick will be to pour some kind of slab at the ends..(we call them abutments) to anchor and support the ends. you typically anchor only one end, and allow the other to slide.

10" is nothing. i wouldnt support from mid span. running water puts crazy loads on columns. the added math wouldnt be worth spanning such a short distance. cool thing about the dually and trailer, you wont be able to put them both on the bridge at one time, so the loading is relatively light.

talking out of my butt here, i bet a simple 12x12 wood corbel bridge would hold up your dually. what does the trailer weigh? a camping trailer? less than the dually?

Well, at least someone addressed what to do with the beams. Abutments, that's half the equation. You can drill for piers, drive pilings or form for a mass of concrete. Otherwise the beams will sink into the sides of the creek bed.

I've seen many old bridges built on wooded abutments. Some that lasted decades. It would not be cool to use railroad ties or otherwise treated lumber as I'm sure they did in the past. Still, if there is an abundance of heavy hard wood timber nearby, that's another approach.

If you know someone with a light drilling rig, you're in good shape if he can back up to the bank.

[red-beard]

Originally Posted by kach22i

expect to pay somewhere between $100-150 dollars an hour for a structural engineer.

Make sure all your work does not wash away in a flash flood. Do you have any information on that creek?

+1

[whiskyb]

Here is a side shot. Trailer on the right need to come over to the right. Concrete blocks on the left are sitting on stone base and have been their several years. I would like to add a few more this year to the right as well. They have supported a very large excavator that had to cross over to dig a pond. The bend in the retaining wall is also from that crossing.

Creek has never rose above 24" in spring run-off in the 30 odd years I have been here.

The actual distance across the creek is about 6' so i was allowing 2' on either side equaling my 10' I was hoping to sit the beams on the concrete and after cutting down my retaining wall place them level on the opposing side. With the water table so high I was going to dig down on the trailer side and pour another concrete pad their as against the existing retaining wall.

2 or 4 beams running across that I could weld into one unit and then cover with the rough cut timbers

Who wants to be first across it? or not

[Seahawk]

Culvert would work great, topped with bank and run or gravel. Then, rocks in front and rear, where needed. You may have a bit of a hump over the creek, but not too much with a bit of skill.

If you have a front end loader or can rent a backhoe, that is a day job, no worries at all. Culverts come in all lengths and widths so you can specify.

Nice project!

[Seahawk]

Originally Posted by Rusty Heap

Calvin and Hobbes Dad explains science | s-anand.net

That man was supremely talented, gifted.

[notmytarga]

That's smaller than I think anyone thought. I say dig it out, lay 12 inch culvert with roadbase support, fill dirt, topsoil, grass seed. It will make the yard "seamless".

[oldE]

"Creek has never rose above 24" in spring run-off in the 30 odd years I have been here."

A 12" culvert isn't gonna handle maximum flow.

If we call the creek bed 72 inches wide and highest he has seen 24 inches, that gives 12 square feet.
I would stay with the span idea, either "I beams" or heavy timbers.
Hopefully that would keep things from getting washed away if the big rain comes.

Have fun.
Les

[Seahawk]

I'd plant a culvert, 24"/36" or more depending on the actual measurements in the channel and enjoy.

The lawn slopes to the ditch, the concrete looks suspect and why worry about where to plant the iron?

This is simple.

[vash]

Originally Posted by Seahawk

Culvert would work great, topped with bank and run or gravel. Then, rocks in front and rear, where needed. You may have a bit of a hump over the creek, but not too much with a bit of skill.

If you have a front end loader or can rent a backhoe, that is a day job, no worries at all. Culverts come in all lengths and widths so you can specify.

Nice project!

seeing the pics..i would go this way.

big 36" galvanized pipe, backfill it with 1" base rock.