Mobile home frame for short span bridge?

markct · Dec 1, 2005

all the house trailer frames i have seen were about 10 inch I beam, but there a very light i beam, not like a standard I beam that most people are used to seeing. i was given a house trailer frame once, i wanted it just for the axles, but took the whole thing, it was 40 ft long and i put some tires on one axle and towed it down the road to my house, well it looked like a wet noodle going down the road, you could see the frame rails swaying side to side, if you use it for a bridge, which i wouldnt if you were talkin anything more than 1000lbs, make sure you put plenty of bracing to keep them from flexing sideways

MikeD74T · Dec 1, 2005

I made a covered bridge with a 24' span. Engineer at a structural steel yard calculated my needs for an 8000 lb live load. Bought 4 26' x 18" used beams with smaller spacer beams for $400 delivered. There was no charge for the calculations. Money well spent to know it's safe. All the spacers were also cut to length to put a pair of beams under each tire. Even bad planks won't let my tractor fall through.

Dargo · Dec 2, 2005

( all the house trailer frames i have seen were about 10 inch I beam, but there a very light i beam, not like a standard I beam that most people are used to seeing. i was given a house trailer frame once, i wanted it just for the axles, but took the whole thing, it was 40 ft long and i put some tires on one axle and towed it down the road to my house, well it looked like a wet noodle going down the road, you could see the frame rails swaying side to side, if you use it for a bridge, which i wouldnt if you were talkin anything more than 1000lbs, make sure you put plenty of bracing to keep them from flexing sideways )

Yes, I think the I beams I'd seen that were in the trees appeared to be lighter than 10 pounds per foot, and made of inferior quality steel. Remember, the mobile home frame is not designed to hold any load heaver than foot traffic. The cardbord box built on top of it gives it considerable rigidity. They are only made to be towed twice; once from the factory, and once to the home site. Our city has now voted to refuse code approval for about 90% of the type manufactured now because of the shoddy and weak construction. An article in our paper recently was titled "Deathtraps disguised as homes". Tests proved that heavy thunderstorm winds could make pretzels of most, let alone any tornado. I've seen little skid steers crush up too many mobile home frames in the last couple of weeks to ever even remotely think they are sturdy by any measurement.

MMM · Dec 2, 2005

Spiker. that's the answer I was hoping for. I think I'll double it and use poles like you mentioned to save blowing holes for deck fasteners. My rears are 82" outside and should center the beams
Have Blue had a good idea in another post to try it out on a not so precarious spot. i can set it up on one of my terraces and try it out for a week or so first. I have a barn Rita destroyed for experimental temporary decking. I'll post an update in Jan. hopefully.

RobA · Dec 2, 2005

( Bought 4 26' x 18" used beams with smaller spacer beams for $400 delivered. )

$400! Wow. Was this recently? I was quoted $450 for a new 10" beam 20 feet long. That was for 1 beam - delivery not included. If that is a recent price I need to find some USED beams. Where can I find used beams?

Darren · Dec 2, 2005

If you're not in a hurry, you may get a better price later. I read that the Chinese have surplus steel they'll be selling. into the world market. Scrap prices in this area dropped months ago.

MMM · Dec 2, 2005

Paying 9 bucks a foot for 70kpsi 3X 3/8 sq tube back in August is what got me interested in alternatives to the steelyard for thie creek crossing.

tommu56 · Dec 3, 2005

our forest dept uses ones like this link on our dirt roads after the last storm they brought about 25 loaded tri axel dumps with stone in to repair road gross wt about 50,000 lbs each over about a 15' span bridge is about 25' over all (5 feet bearing on each end)

http://www.fpl.fs.fed.us/documnts/pdf1995/ritte95a.pdf

mabe use the frame for the side plates like drawing in link

MikeD74T · Dec 3, 2005

The steel fabricator I got my beams from also runs a scrap yard. That price was for used steel after I told them I couldn't afford their first quote which was for new. Try scrap yards or demolition companies for used. Our snowmobile club has since bought used beams from the same company. Our last bridge was two 36" beams X 75' span with a 12' wide deck of 3" pressure treated decking.

dent8 · Dec 4, 2005

I didn't see any reference in your link to the dimension of the lumber used for these bridges. Do you have an estimate of the ones you see? Our bridge is an old 40' semi-trailer well beefed. Pretty good sized trucks have used it, but cement trucks use the low water crossing. I've read that many of you like pictures so I'll give a try. Let me know if I shrunk it appropriatly (assuming I get it to attach).