bridge type selection

[cvg]

I'm sure this has probably been discussed before, but I can't find it. What are the pros and cons of AASHTO pre-cast girder bridge vs box beam bridge vs superbox culvert "bridge"

 

[cvg]

ok, I'll start and assuming very little skew and no horizontal curvature and assuming relatively short overall span, perhaps a few hundred feet...

AASHTO pre-cast girders are
easier to design
shorter span lengths
taller supperstucture / higher overall bridge profile
faster to construct
cheaper

boxed beam bridge
harder to design
longer span lengths
narrower superstructure / lower bridge profile
takes longer to fabricate
more expensive

superbox culvert
less hydraulic capacity than a true bridge
lowest overall profile
more impact on riverbed

 

[Drumchaser]

AASHTO pre-cast girders
+ allow easier deck forming system ~ PCP's or PMD's
allow less work on-site than forming Bridge class box culvert
- more $ goes to supplier instead of the contractor and local economy

box beam bridge
+ faster construction on-site
- more $
- normal lengths are 100 LF and less

Bridge class culvert
+ more $ to be made (or lost) by the contractor on-site and the local economy
(takes the supplier out of the equation)
- takes considerably longer to construct (in most cases)
- seasonal and more weather dependant

 

[cvg]

if I go from 6 span AASHTO Type 4 at approx 100 ft per span (600 foot total length) to 5 span AASHTO Type 6 with 120 ft span I am saving a lot of money on a proposed bridge. Anybody want to venture a guess how much?

 

[Drumchaser]

cvg


Off the top of my head with no verification.

The type 6's we have seen... utilized inverted-T (interior) caps...so the cap(s) are more $.
The 6's obviously cost more. (than 4's)
Eliminating a span (8?) of beams, as well as a bent of foundations, columns, and cap.

A little more labor utilizing the 6's.
They are significantly more unstable.
Bracing will be a little more.

Assuming the design for the foundations, columns, and caps would change a little...appears that it would be cheaper to go with the Type VI Design.

So ...... how much cheaper?

 

[cvg]

104' wide bridge with superelevation

would be eliminating 1 set of drilled shafts, pier caps, piers and approximately 18 girders.

Circular/multi-column piers with dropped-type pier caps or hammerhead piers are recommended at the pier locations. Inverted tee pier caps can be used; however this type of pier cap was not recommended due to increased cost. drilled shafts are the recommended foundation type.

 

[Drumchaser]

So ...... how much cheaper?

 

[cvg]

thats my question

 

[Drumchaser]

$12,667.21

 

[Mac75]

I am looking for some help on assessment of post tensioned box beam bridge.I have modelled it as a 2D Grillage.How can i analysis the web & diaphragm stressess in it?

Any help will be appreciated.