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Author Topic: Texas' trapezoidal precast beams  (Read 2484 times)

Tom958

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Texas' trapezoidal precast beams
« on: November 21, 2021, 08:34:38 AM »

Do these handsome trapezoidal bridge beams have a name? I like them a lot, and with many miles of viaduct proposed for upcoming managed lane projects in my own city of Atlanta, I'd very much like to see them used here instead of the oppressively ubiquitous AASHTO beams. I guess that after the I-85 viaduct fire and collapse, GDOT prefers to use beams that can be ordered from a catalog as much as possible, but I don't see why these couldn't be about as easy to procure as AASHTO beams if they became as common here are they are in Texas.
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jeffandnicole

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Re: Texas' trapezoidal precast beams
« Reply #1 on: November 21, 2021, 08:59:46 AM »

Post tensioned concrete box girders.

https://www.fhwa.dot.gov/bridge/concrete/hif15016.pdf

As for Georgia, or any state for that matter, it's all about what works best for a particular project, costs, height of span and clearance needed, and other factors. Texas has ordinary I-beams as well. There's nothing pre-made to procure, as all bridge elements are designed and built specifically for each project.
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Tom958

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Re: Texas' trapezoidal precast beams
« Reply #2 on: November 21, 2021, 09:23:32 AM »

Post tensioned concrete box girders.

https://www.fhwa.dot.gov/bridge/concrete/hif15016.pdf[/url]

This document is about poured-in-place box girders that are built on falsework and are far too wide to precast and lift into place, and utterly unlike what I asked about and provided an illustration of.

Quote
As for Georgia, or any state for that matter, it's all about what works best for a particular project, costs, height of span and clearance needed, and other factors. Texas has ordinary I-beams as well. There's nothing pre-made to procure, as all bridge elements are designed and built specifically for each project.

I didn't say premade, did I?

Look: If an agency wants to build an AASHTO beam bridge, there's no need to design the beams from scratch it the way that'd be done with a post-tensioned box girder. Decide upon the span length and load requirements, and look up a design that's undoubtedly on file and which has probably been fabricated many times before. 
« Last Edit: November 21, 2021, 09:31:31 AM by Tom958 »
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edwaleni

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Re: Texas' trapezoidal precast beams
« Reply #3 on: November 21, 2021, 11:16:25 PM »

The trapezoidal precast beam was developed in 1999 by 2 engineering professors at the University of Nebraska-Lincoln and structural engineer from Egypt as a cost saving method vs AASHTO standard beams.

You can read their formal submission in the Journal of the Precast Concrete Institute here:

https://www.pci.org/PCI_Docs/Publications/PCI%20Journal/1999/Jan-Feb/Precast%20Pretensioned%20Trapezoidal%20Box%20Beam%20for%20Short%20Span%20Bridges.pdf
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jeffandnicole

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Re: Texas' trapezoidal precast beams
« Reply #4 on: November 21, 2021, 11:28:51 PM »

Post tensioned concrete box girders.

https://www.fhwa.dot.gov/bridge/concrete/hif15016.pdf[/url]

This document is about poured-in-place box girders that are built on falsework and are far too wide to precast and lift into place, and utterly unlike what I asked about and provided an illustration of.

Quote
As for Georgia, or any state for that matter, it's all about what works best for a particular project, costs, height of span and clearance needed, and other factors. Texas has ordinary I-beams as well. There's nothing pre-made to procure, as all bridge elements are designed and built specifically for each project.

I didn't say premade, did I?

Look: If an agency wants to build an AASHTO beam bridge, there's no need to design the beams from scratch it the way that'd be done with a post-tensioned box girder. Decide upon the span length and load requirements, and look up a design that's undoubtedly on file and which has probably been fabricated many times before. 

Well then. I guess you'll just have to live with and look at the bridge beams Georgia orders from catalogs.
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Tom958

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Re: Texas' trapezoidal precast beams
« Reply #5 on: November 22, 2021, 04:42:51 AM »

The trapezoidal precast beam was developed in 1999 by 2 engineering professors at the University of Nebraska-Lincoln and structural engineer from Egypt as a cost saving method vs AASHTO standard beams.

You can read their formal submission in the Journal of the Precast Concrete Institute here:

https://www.pci.org/PCI_Docs/Publications/PCI%20Journal/1999/Jan-Feb/Precast%20Pretensioned%20Trapezoidal%20Box%20Beam%20for%20Short%20Span%20Bridges.pdf

Thanks! To address my question, I guess they don't have a specific name.
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longhorn

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Re: Texas' trapezoidal precast beams
« Reply #6 on: November 22, 2021, 04:07:46 PM »

I don't know the name but I do know these bridges went up quickly up and down the I-35 rebuild. Also steel beams can be used instead of concrete.
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Bobby5280

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Re: Texas' trapezoidal precast beams
« Reply #7 on: November 22, 2021, 04:42:47 PM »

I wish Texas could build some of its directional stack interchanges using cast segmental methods, like what has been used on the newest directional interchanges in the Phoenix area. Fewer support pylons are needed and the end result looks more attractive, even graceful or elegant. The I-35W/I-820 interchange on the North side of Fort Worth is about as impressive as interchanges can be, but all those square, boxy beams and uprights are pretty ugly looking.
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MaxConcrete

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Re: Texas' trapezoidal precast beams
« Reply #8 on: November 22, 2021, 06:34:20 PM »

The I-35W/I-820 interchange on the North side of Fort Worth is about as impressive as interchanges can be, but all those square, boxy beams and uprights are pretty ugly looking.

I agree, many of the new freeways and interchanges built in DFW in the last 10 to 15 years have very unattractive concrete structures. This is especially true for the tolled managed lane facilities. The huge ramp structures at 635/35E and 820/121/183 are especially unsightly. The massive interchange at 35E and 121 is another interchange which could have been much nicer. Unfortunately unattractive structures are still being built, such as the ramps at SH 170 and IH 35W. These structures will probably be in service for a long term, perhaps until 2100.

Some recent work is very nicely designed, such as the Chisholm Trail parkway. The Dallas Mixmaster is okay, not attractive but not ugly.

For work in progress, the LBJ East project is using attractively designed structures. The piers at the 30/360 interchange are intermediate between attractive and ugly.

Houston does a much better job of using used architecturally enhanced designs. Everything built in the last 20 years is generally attractive. There are actually multiple themes used in different areas. The southeast side toward Galveston uses the "wave" design. Northwest Houston near the pine forests uses the pine-tree pier design. Central Houston mostly uses a nice enhanced pier design, I call it enhanced flare.
« Last Edit: November 22, 2021, 09:36:26 PM by MaxConcrete »
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MaxConcrete

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Re: Texas' trapezoidal precast beams
« Reply #9 on: November 22, 2021, 06:39:31 PM »

IH-69 (US 59) in northeast Houston, built to its current configuration in the 1990s, uses trapezoidal precast beams. They may be different than the design mentioned in a previous post. To the best of my memory, this was the first large-scale use of trapezoidal precast beams in Houston. In the locations below at Little York and Tidwell, you can see how the design tries to be smooth to approximate California-style cast-in-place concrete.

https://www.google.com/maps/@29.8701625,-95.329683,3a,75y,341.97h,99.44t/data=!3m6!1e1!3m4!1s7V3cTfrtxG4jxJb-9dCktg!2e0!7i16384!8i8192?hl=en

https://www.google.com/maps/@29.8486426,-95.3331647,3a,75y,241.55h,93.37t/data=!3m7!1e1!3m5!1sCDTS1xTe37hEK5ZfBMOJJw!2e0!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fpanoid%3DCDTS1xTe37hEK5ZfBMOJJw%26cb_client%3Dmaps_sv.tactile.gps%26w%3D203%26h%3D100%26yaw%3D168.329%26pitch%3D0%26thumbfov%3D100!7i16384!8i8192?hl=en

Tom958

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Re: Texas' trapezoidal precast beams
« Reply #10 on: November 22, 2021, 09:32:18 PM »

C/o TxDOT, this is what freeways look like on the planet Vulcan.  :love:

Fuller disclosure: I'm in Atlanta, where we built three legit California-style box girder interchanges, but have since regressed to an utter lack of aesthetics, especially on the still-under-construction 285-400 interchange. Georgia is developing a segregated managed lanes system that'll involve miles of viaducts along I-285. I'd rather see something that's a bit more attractive than AASHTO beams used for that project. I seriously doubt that GDOT would go for cast-in-place box girders, precast segmental, or steel tub girders, but these easily-fabricated beams might have a chance. It'd be great if they were used more widely across the state, too, and became as routine as AASHTO beams.
« Last Edit: November 29, 2021, 08:07:18 PM by Tom958 »
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