Precast/Prestressed Concrete Box Girders
Precast/Prestressed Concrete Box Girders
(OP)
I am currently working on the design of a precast/prestressed concrete box girder (a bunch of box girders laid side by side,) each girder has one square opening at the center (about 70% of the total x-sectional area) and spans approximately 10 meters.
I have never designed a box girder before, let alone one for a bridge! I am designing it as per AASHTO 1998. I am curious, is there anything out of the ordinary that I should pay attention for that someone whose been accustomed to building design would miss? Any special considerations?
Are there any guides out there that can put me in the right direction?
We're also looking to purchase a software that will aid us in designs like this one. We've been using Concise Beam for our precast/prestressed beams but that software does not have the bridge code. Is there a software out there ($500-$1000 range) that we should be eyeing for this application?
Thanks,
I have never designed a box girder before, let alone one for a bridge! I am designing it as per AASHTO 1998. I am curious, is there anything out of the ordinary that I should pay attention for that someone whose been accustomed to building design would miss? Any special considerations?
Are there any guides out there that can put me in the right direction?
We're also looking to purchase a software that will aid us in designs like this one. We've been using Concise Beam for our precast/prestressed beams but that software does not have the bridge code. Is there a software out there ($500-$1000 range) that we should be eyeing for this application?
Thanks,
Clansman
"If a builder has built a house for a man and has not made his work sound, and the house which he has built has fallen down and so caused the death of the householder, that builder shall be put to death." Code of Hammurabi, c.2040 B.C.






RE: Precast/Prestressed Concrete Box Girders
Clansman
"If a builder has built a house for a man and has not made his work sound, and the house which he has built has fallen down and so caused the death of the householder, that builder shall be put to death." Code of Hammurabi, c.2040 B.C.
RE: Precast/Prestressed Concrete Box Girders
RE: Precast/Prestressed Concrete Box Girders
Clansman
"If a builder has built a house for a man and has not made his work sound, and the house which he has built has fallen down and so caused the death of the householder, that builder shall be put to death." Code of Hammurabi, c.2040 B.C.
RE: Precast/Prestressed Concrete Box Girders
RE: Precast/Prestressed Concrete Box Girders
RE: Precast/Prestressed Concrete Box Girders
RE: Precast/Prestressed Concrete Box Girders
Why are you using 1998 AASHTO? Should be using the latest LRFD code?
Also some DOT's like Illinois DOT has charts for the design of their box girders.
Regards,
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Qshake
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RE: Precast/Prestressed Concrete Box Girders
I was able to find some great standard details on Oregon's DOT.
I was able to download the trial license software for Conspan and browse through it. It seems perfect for my application, definitely something we will consider (still waiting to recieve a quote from them.)
Clansman
"If a builder has built a house for a man and has not made his work sound, and the house which he has built has fallen down and so caused the death of the householder, that builder shall be put to death." Code of Hammurabi, c.2040 B.C.
RE: Precast/Prestressed Concrete Box Girders
RE: Precast/Prestressed Concrete Box Girders
There is a lot of theory available for download together with design examples. Then, try the Pennsylvania DOT for thier PS3 software.
RE: Precast/Prestressed Concrete Box Girders
Never, but never question engineer's judgement
RE: Precast/Prestressed Concrete Box Girders
RE: Precast/Prestressed Concrete Box Girders
Box girders are erected side by side and have a continuous shear key along the top that gets filled with NS-grout. Then they are laterally post-tensioned together with a couple of 0.5" dia. strands in PT ducts running thru intermediate diaphragms. This enables load sharing between box girders.
Make sure to talk to local precasters on details and std construction practices. Watch out for skew of bridge girders - eventually you reach a point where girders are skewed too much to PT together laterally, PCI Bridge Manual has something on that.
RE: Precast/Prestressed Concrete Box Girders
RE: Precast/Prestressed Concrete Box Girders
RE: Precast/Prestressed Concrete Box Girders
Having two layers of strands means that the beam will still have some strength even when the bottom strands rust and spall. This makes it possible to notice the problem in time to fix it before the whole thing comes down.