Minimum number of girders of prestressed bridge
Minimum number of girders of prestressed bridge
(OP)
Hi,
I am designing two lanes 30m span prestressed bridge and the width of the bridge is 8.3m for south bound lane for expressway. I have put four girders with girder spacing of 1.8m. But my boss is not happy that I am using four girders he is asking me where in the code it mentions minimum number of girders is four. I have found in Texas Design Specification that minimum number of girder is four. But can anyone direct me where I can find that the minimum number of girders is four.
Thanks,
I am designing two lanes 30m span prestressed bridge and the width of the bridge is 8.3m for south bound lane for expressway. I have put four girders with girder spacing of 1.8m. But my boss is not happy that I am using four girders he is asking me where in the code it mentions minimum number of girders is four. I have found in Texas Design Specification that minimum number of girder is four. But can anyone direct me where I can find that the minimum number of girders is four.
Thanks,






RE: Minimum number of girders of prestressed bridge
do you guys have to consider failed structure ? ie would you have to carry load on only 3 of the 4 (or 4 of 5) girders ?
another day in paradise, or is paradise one day closer ?
RE: Minimum number of girders of prestressed bridge
RE: Minimum number of girders of prestressed bridge
RE: Minimum number of girders of prestressed bridge
another day in paradise, or is paradise one day closer ?
RE: Minimum number of girders of prestressed bridge
CooperDBM makes several good points.
www.PeirceEngineering.com
RE: Minimum number of girders of prestressed bridge
RE: Minimum number of girders of prestressed bridge
another day in paradise, or is paradise one day closer ?
RE: Minimum number of girders of prestressed bridge
RE: Minimum number of girders of prestressed bridge
yes, the road deck might not be as durable (with three girders) but the penny you are saving today is yours (or maybe the current politician's if you're bidding for the work now) and the pound you're spending tomorrow is someone else's ! an important business/politics consideration !!
and, yes, I know that's not how an engineer is supposed to think but that's pretty much how the world thinks today.
this usually leads me back to thinking about ...
a) the definition of a horsepower ... more than double what any reasonable horse can produce (Watt didn't want to be beaten by some overly ambitious nag), and
b) the London sewerage system ... built so over-spec that it still works pretty well today ... these days any highway is usually undersize when it's completed (we don't build in much room for growth).
another day in paradise, or is paradise one day closer ?
RE: Minimum number of girders of prestressed bridge
struct123456 if your client (is it the Texas DOT?) has a minimum girder requirement then they should be part of the decision on economics in the end. You'll need their approval anyway.
RE: Minimum number of girders of prestressed bridge
Also, please pardon my question. The RCC piers are almost 45m in height. I have not designed over 20m piers. Any thoughts?
RE: Minimum number of girders of prestressed bridge
Now if your boss is an accountant, all bets are off.
RE: Minimum number of girders of prestressed bridge
it's also the client's position to value long term benefits over short term costs (and so not give the contract to the lowest bidder) ... but that means that one group of politicians pays for it, and another group (presumably the ones who pushed the others out of office 'cause of "inflated" spending) who'd reap the benefit.
however not giving the contract to the lowest bidder would probably attract a law suit (in the US) ...
company ... "you favoured another proposal, even though our's was cheaper"
politician ... "yes, but there design was 'better'"
company ... "your RFP didn't express the 'value' of these features. our design met the contract requirements and was cheaper"
politician ... "yes, but their's was 'better'"
company ... "ours would have been 'better' if you'd included those features in the RFP"
sigh
another day in paradise, or is paradise one day closer ?