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a2mfk (Structural) (OP)
26 Jan 11 11:50
This job is in the preliminary/proposal stage.

Single span pedestrian bridge to also support golf carts, no vehicles. 8ft wide by 40ft long, simple span over a canal, steel beams...

I don't currently own this but will order it:

LRFD Guide Specifications for Design of Pedestrian Bridges, 2nd Edition

Does this have all of the loading and basic design criteria?

I have seen a range of live loads given online, for preliminary purposes can I use 85psf? Any thoughts on the golf carts (live load plus concentrated load?) would be welcome.

The client wants bar-grate decking. Obviously we will need guard rails, should we automatically go to a truss design which combines the bridge girders and guardrails (using HSS)? Or will two wide flange beams with cross members, and separate guard rails be just as simple and therefore economic?

Everything will end up being hot-dip galvanized.

Thanks for your input!
  
bridgebuster (Civil)
26 Jan 11 13:44
"Does this have all of the loading and basic design criteria?" - Yes, however the pedestrian live load in the LRFD Guide Spec is 90psf (even though the LRFD Bridge Spec  uses 85).

I think 90psf should cover just about everything. Based on your surface area, 90psf is probably equivalent to at least 20 golf carts with two people in them.

Also, the specs require that a barrier be in place to prevent vehicles from crossing the bridge. Otherwise you have to design for H5.

I think two WF's would be cheaper. You could try calling ConTech - they manufacture these types of bridges.
JStephen (Mechanical)
26 Jan 11 13:54
I would assume that if a vehicle can fit on it, at some point it will be used on it.

I say this because our local greenbelt walkway/bikeway is basically a wide sidewalk with motorized vehicles prohibited.  But cops still drive their cars on it.  The little bridges on it are rated for 5,000 lbs, I think.
a2mfk (Structural) (OP)
26 Jan 11 13:56
Thanks bridgebuster, I will look into ordering that spec too, what is the exact name?

You are thinking we would need barriers even with an 8ft wide bridge?  
bridgebuster (Civil)
26 Jan 11 15:11
a2mfk:

It's called "LRFD Guide Specifications for the Design of
Pedestrian Bridges" (December 2009).

Let me clarify  "barrier". I meant  something to physically prevent a vehicle from getting on to the bridge. I wasn't referring to a railing to protect pedestrains on the bridge.  
hokie66 (Structural)
26 Jan 11 15:17
If the bridge is designed for 85 or 90 psf live load, light vehicles like cars would be no problem.  Not trucks or trailers with loads of sand, though.
a2mfk (Structural) (OP)
26 Jan 11 15:19
I gotchya, I had envisioned a pair of bollards anchored in concrete and painted a pretty yellow spaced less than the standard width of a car, though this is a military base so if they object I just say YESSIR!!!  Maybe they'll insist on only a sign. This is way early one but I will keep that in mind. How much can a tank weigh anyway. JOKING, I think this is on some back trail through the property in a recreation area.
ACtrafficengr (Civil/Environmental)
26 Jan 11 15:45
Isn't H10 often specified for ped bridges, to allow maintenance and emergency vehicles to cross?

     "...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

bridgebuster (Civil)
26 Jan 11 15:46
The Army being the Army will put up the bollards because the specs call for it.

BTW the Army Bridge Manual says tracked vehicles range from 4 to 150 Tons.
a2mfk (Structural) (OP)
26 Jan 11 16:00
these are jet jockeys near the beach in FL... I think this pedestrian and golf cart bridge gets them to the sand beach volleyball courts where they play with no shirts and in jeans
efsinc (Structural)
28 Jan 11 19:34
Any pedestrian bridge that provided a view that might attract a crowd for any occasion, I would give consideration to using an exit corridor live load.

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