huangyhg

portable bridge h20 loads! steel deck thickness?
trying to come up with cost effective portable temporary bridge design 12 x 12 feet. all steel construction and steel plate deck welded directly to beams.
where/how/tables? do i calculate the minimum thickness required of the steel deck? one way-two way loading, all tables and most spreadsheets and formulas i find are for uniform loading per square feet... not sure how to translate that intelligently into a 20"x10" 16,000 lbs point load from wheel/s. (32000 total axle load at one time in bridge.
so far using beams at 17" on center. 7/16" a36 plate? seems thick... 3/8"?
any thoughts?
it sounds like you're trying to come up with some sort of orthotropic system. look at aashto for code requirements.
aisc sells a manual for orthotropic design.
look in the design specs under naval architecture - ferry boats have to deal with those loads all the time and they use metal plates with stiffeners to support the loads between the purlins and girders.
mike mccann
mmc engineering
for a temporary bridge you may find it easier to use steel bar grating. load tables are available.
for my $0.02, i would use or seek out the references from both mssquared and ifrs.
we use a lot of steel plate, with and without stiffeners for temporary construction of highway facilities.
if this is indeed for temporary construction, i would presume that the contractor has given you an inventory of available sections for use.
also, aashto has two references for design of temporary works.
regards,
qshake
eng-tips forums:real solutions for real problems really quick.

another solution we use is crane mats made of railroad ties. these are typically tied together with 1" threaded rods and can certainly be made 12' by 12'.
regards,
qshake
eng-tips forums:real solutions for real problems really quick.

12' x 12' is not very portable. it is too wide or too tall to trnsport by truck. you might want to keep the bridge sections at 6' wide and use two which could be connected in the field. each 6' wide section, 12' long (a very short bridge!) could have two to three beams depending on the deck strength.
im not havin much luck with the "standards" or finding tables for this application...
using a steel plate design spreadsheet for 2 way loading (which can simulate 2 way loading for length>>width) i am getting 3/8" thick deck required to span the 15" clear between beams at 17" on center ... thinking about bumping it up to 7/16" just for good measure. the whole thing will weigh 3500# ... kinda heavy! w10x12 at about 17" o.c.
(am also spec'ing a 1/4" 4x4 angle at each end to stiffen it during placement and transport....)
client wants this size in particular... 12 feet wide so he doesnt have to worry about driving straight mabye ... 12 feet long to get the trucks over rutts, creeks, etcc i suppose...
peinc! good comment on designing 2 sections... will bring this up to client. genius!!!!
show me the table!!!
i will pursue the steel bar grating and naval avenues.. but pretty sure wont have em in office....
appreciate the posts.. keep em coming and check out my other posts - "rotting glulam splice" <--- or something like that.

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