Jointless Bridges
Jointless Bridges
(OP)
I'm looking at designing a 50' single-span filled-spandrel arched bridge. The bridge will be constructed entirely of concrete and filled with soil. Abutments will be cast against rock. An example can be shown here:
http://www.fhwa.dot.gov/nediv/bridges/unname1.jpg
It would be very easy to construct the arch slab and walls integrally with the abutment, but I'm concerned about thermal stresses without any expansion joints. The bridge will be located in a tropical/humid climate and above water, so I think that AASHTO recommendations are too conservative. However, in modeling the arch with fixed supports under temperature change in accordance with AASHTO, the results are extreme. This concerns me and makes me hesitant to simply discount the load.
I know that Tennessee uses jointless bridges a lot, but I can't find any solid guidance on the issue. Any thoughts on how I should tackle this?
http://www.fhwa.dot.gov/nediv/bridges/unname1.jpg
It would be very easy to construct the arch slab and walls integrally with the abutment, but I'm concerned about thermal stresses without any expansion joints. The bridge will be located in a tropical/humid climate and above water, so I think that AASHTO recommendations are too conservative. However, in modeling the arch with fixed supports under temperature change in accordance with AASHTO, the results are extreme. This concerns me and makes me hesitant to simply discount the load.
I know that Tennessee uses jointless bridges a lot, but I can't find any solid guidance on the issue. Any thoughts on how I should tackle this?





RE: Jointless Bridges
http://www.con-arch.com/home.html
http://www.con-span.com/con-span/main.html
RE: Jointless Bridges
RE: Jointless Bridges
Regards,
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RE: Jointless Bridges
RE: Jointless Bridges
RE: Jointless Bridges
Not sure why you would have pre-mixed bags of cement/aggregate. I would prefer to keep the cement separate until time to mix the concrete.
It sounds as if the temperature range where you're working is not very high.
RE: Jointless Bridges
AASHTO recommendations are likely fine, hinterland American bridges are subject to much higher temperature variations; as hot and inhospitable as the tropics may seem it is temperate. Plus the bridge is so short, no problem being integral.
I suppose that you are using an arch so that you can minimize the steel quantity and this is making you worry about temperature cracks.
Good luck.