Finding the maximum moment for the
girder(s) with the vehicle load is somewhat tricky, especially by hand
(without computer software). If you use a 10K vehicle you can check me
with the follow equations:
Assumption: Back wheel = 4K and front
wheel = 1K (Spacing between wheels is 5'-6" and wheel span is
Hint: The CG of the vehicle is 1.1 ft left of
the center line of the span, L/2 (that would be the rear wheel)
M = 1.25*L + 6.05/L - 5.5 K*lbs
R (left support) = 5 - 5/X - 11/L
X is the distance from the left support to the
center of the back wheel.
Make sure you prove these formulas before using
them. It's been a while since I derived them. But, I had them
Thanks to Bill he knew the word Bollards for
those metal posts at the end of the bridge. Space them as
Don't forget to buy your AASHTO manual.
You'll pay for it with your first bridge.
Universal Building Specialties,
Auburndale, Florida 33823
----- Original Message -----
Sent: Monday, June 04, 2001 7:55
Subject: Golf Course Bridge
I am designing two cart path bridges
for a golf course. First bridge is 3 span 70'+50'+50', second bridge
has a single span of 70'.
Wonder of wonders, the owner and the
contractor both want to minimize the cost on the structures, and are
asking that I use the minimum live loading possible.
The largest vehicle used on the golf
course is a mower/utility vehicle with a gross weight of about 2 tons,
well below H15 loading. The bridges themselves are to be 10 feet
wide, and the approaches are so hilly that it is unlikely that a
truck could even get to the bridges.
Soooo, my question is : Does anyone
have experience regarding the use of loads substantially less than those
required by AASHTO for the design of NON-highway bridges. If so, are
there standard loads? I was thinking of using 5 tons as a minimum,
and having the owner post a permanent sign showing the weight
Also, does the AASHTO manual govern
the design of the bridges? We are currently under UBC94, soon to
switch to the IBC, but I am not all that familiar with AASHTO requirements
(not much bridge work on Guam). I would prefer to use UBC94, LRFD
2nd Ed for the girders, and refer to AASHTO for load distribution (based
on 5 ton total weight) and seismic design.
T. Eric R. Gillham PE
PO Box 3207 Agana Guam 96932
Ph: (671) 477-9224
Fax: (671) 477-3456
Cel (671) 687-7115