bridge construction

huangyhg

bridge construction
we are trying to design a bridge to cross a creek that will support our farm tractor (with wagons containing hay which would weigh in total about 12 ton).  the creek is 60 feet bank to bank.  what would be the most economical way to span this creek to support the maximum weight?

i would think that you may be able to use a couple of steel beams with a timber deck. perhaps the abutment could be either timber or concrete. you may have to dig a couple of pits to investigate the soils conditions at each abutment.
it would be advisable to hire a structural engineer to design it for you.  
best of luck!
jimbo (staff)22 mar 04 16:26
there is a bridge engineering forum on the site. might try there.
buy a dictionary, keep it nearby and use it. webster's new world dictionary of american english is recommended, and webster's collegiate dictionary.
60 feet is a river
a creek is limited unless at an estuary
so if this is an estuary you need a bridge engineer and a stack of piled foundations for soft soils affected by river water inflow and subisdence
lateral stress on foundations is high and the sides may displace and the surface rise
if a creek and not rock it must have low strength soils
the ground must be near saturated at times and if not then the soils will dessicate
no way would a steel girder decking arrangement suffice without some serious abutments and
it might be good to transfer to stress to the sides by using a slight pre-formed arch on good angled piles, but
with tractor weight you are going to risk twisting the structure as the machinery moves the load across so dynamic state has to be considered and this is where most bridges and culverts begin to founder and at best you end up with a subsided unusuable mass if steel and wood. is there a shorter way around i.e. cheaper by going around some existing paved zone ?
it could be a lot of expense for very little result and much eroded foundered muck 'n 'ay
possibly your life under an unstable tractor frame
sincerely
mikehydrophys
mdshydroplane