I Beam help needed

[Parttimer]

Eddie, (the chart) says that a W8 X 10 steel beam can carry a load of 17 kips, (17,000 lbs) for a span of 10 feet. I would assume they are expecting the load to be continuous. You are correct with the 8" being the vertical dimension the 10 is the weight per foot, and the W is the shape-name of the beam.

Dave

 

[bugstruck]

Eddie,

Hello, been awhile. I can't find my old I beam span tables but 17,000 lbs loading for a W8x10 sounds heavy to me. May be a good grade of steel or my memory? I assume that loading chart is for a uniformly distributed load as it's for a construction deck or roof. Your tractor is applying concentrated or point loads. Now granted, if your beam is supported at 10' intervals, you probably won't have more than one axle on one span at a time. Also, will any RV daredevils have vehicle access to this? /forums/images/graemlins/shocked.gif

I'm no engineer so I won't offer advice, but if I were doing my bridge I think W8 x 18 would be more like it. W 8 x 10 is the lightest residential beam I've ever placed for a wood joist deck loading. They aren't much. Who knows, that 18 pound beam could fail the point load test for a 2,500 lb. axle midspan, but I seriously doubt it as the two beams share the load. Also, I assume I'd be drilling for the decking attachment and the size and spacing on the top flange holes could come into play for the caculations. Doubt that is of much consequence though. Even the beams I'd do mine /forums/images/graemlins/tongue.gif with wouldn't suffice for any truck traffic much over a pick-up, assuming equal wheel spacing to my tractor. Wouldn't hurt me to get at least a steel angle or two cross brace for the bottom of the beam at say mid or third spans? That's a shallow beam, but I'd still mitigate any rotational movement under loading. The decking should more than control the top. Also, I'd consider narrower vehicle traffic or anything moving loads off the beam centers without structural decking. If I did that with inadequate decking structure any calcs would go haywire and I'd be asking for trouble.

Again, I'm talking about my bridge /forums/images/graemlins/grin.gif I don't worry about you, but not everyone has your experience and good sense with materials to build my bridge. No offense meant to others of course.

Take Care!!

 

[CurlyDave]

Eddie:

I would consider making this as a series of culverts next to each other, so the view from the direction the water is flowing is :
_______________
O O O O O O O
--------------------

Alternatively, you could make this with square tubes. The tubes would be formed and poured as part of your concrete spillway.

The top surface would be concrete, which is a lot better as a driving surface than PT wood.

You would need re-bar in the concrete, but to me, that is a lot easier than the I-beams since each piece is relativly light and can be placed where it is needed.

You still need to have the concrete engineered, but I think construction would be easier.

While I know how to do the calculations, I am not a PE and can not legally give you a design. I really think yor best bet would be to talk to a local engineer, who could give you a couple of basic design choices for your bridge and then do the calculations of the one you like for a couple hundred $.

I bet it would save you more than his costs by minimizing the materials costs to you.

The other advantage of this design is that you could embed galvanized fence posts in the concrete between the tubes for railings. You are going to need sturdy, attractive railings to prevent people from falling off the edge into the water and suing you.

 

[rambler]

I'm sorry I'm not any help to you, but I have a question or 'what-if':

Sounds like this is a pretty good lake & spillway, there must be some acres of drainage behind it. Is there any chance of trees & other debris coming floating down the river? Are you raising the I-beams, or an arch design, to prevent your spillway from getting plugged? You are putting a cap on the top of the spillway, and anything blocking it up could lead to problems under severe conditions.

I would be concerned with any of the culvert or square hole ideas for the same reason.

When you see pictures of floods & bridges going down, it is always piled full of trees around the supports. You are turning a 18-20 foot span open to the top into (2) 10 foot spans, with a cap on top. That can snag a lot of things trying to float by....

Like you say, liability issues, don't want to turn your spillway into a dam. Here in MN with the ice flows & spring run-offs, it would be a big concern. Where you are, might not be anything to it.

--->Paul

 

[scott_vt]

Mornin Eddie,
We calculated about 1000-lbs for decking weight, 2" thick decking. Bringing our total load to 7000lbs. The engineer seems to think that two W8 x 24 wide flange I beams would be more than sufficient to handle the load going across that span with a center support.

I will try and get additional info soon.

scotty /forums/images/graemlins/grin.gif

 

[pekabu]

What about Live loads? I am not an engineer, but a Trail Master for a Snowmobile club. We redecked a bridge with the cement pads used in boat landings, and luckily one of the volunteers was an engineer. Anyway, he figured out the live loads based on our groomers and we ended up ok. Luckily the beams we had were pretty big to begin with.

 

[scott_vt]

Your welcome Dave /forums/images/graemlins/grin.gif

scotty

 

[frank29]

I built a simple bridge about 20 years ago. The main members are four (4) W8x10 x 20' spaced at 2' centers. The ends are embedded in a dirt/broken brick mixture. There is no center support; the clear span is around 15'.

The decking is bar grating (I think it is 1/4" x 1 1/4") that is welded to the beams (including the portion embedded in the bank.

The heavist load it has seen is a Ford F350 overloaded with 4,000 pounds of presure treated wood & concrete.

If I had to do it over, the only thing I would change is increasing the approx 8' width.

 

[inveresk]

Safe load tables won't give you what you need - they have information on uniformly distributed load only. Point loads and dynamic loads need to be calculated for each individual case. It's not difficult to calculate the maximum bending stress and so size a couple beams given a dynamic load but there are liability issues that would encourage the use of a licensed structural engineer.

I know this is a doubled edged sword as he'll probably not want to stop at the beams but likely want to design the foundations. Your local building inspector should be able to recommend a couple of local engineers who are not too hard to pay and who you can get competitive fee quotes from.

On loading, if your tractor is 4000 pounds, might be best to take account of additional implements that might be attached, at least one person and possibly a loaded FEL? Even if you don't have one just now, would be a shame if you got one in the future but couldn't cross the bridge with it. The other consideration is whether you might have aloaded trailer going across.

 

[MF1455v]

Eddie, I no engineer and could not even come close to giving you the quality info you have already gotten, but here is my thoughts.

There is a lot of trailer mfg. shops in East Texas. The closest one to you I can think of is in Ben Wheeler, but I'm sure there's others. Stop by one and ask what size I Beam there using on trailers rated about the weight you are looking for. Example: Gooseneck trailer with tandom 7k lb axes 14k total weight minus 4k or so for the weight of the trailer, will handle roughly 10k load. Most trailers that size are 20 plus feet.

James