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Miami Pedestrian Bridge, Part VII 51

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JAE

JAE

Structural
Jun 27, 2000
15,444
A continuation of our discussion of this failure. Best to read the other threads first.

Part I
thread815-436595
Part II
thread815-436699
Part III
thread815-436802
Part IV
thread815-436924
Part V
thread815-437029
Part VI
thread815-438451




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I notice FDOT is missing from the chart...

Dik
 
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Hokie66 said:
My recollection is that all the ceiling hanging bolts were replaced or supplemented with Hilti mechanical undercut anchors.
Click to expand...

You're recollection is good... problem came about because they 'switched/substituted' the epoxies and used a quick setting one that had 'creep' characteristics. I agree with the use of undercut anchors. We had a really good discussion with the local Hilti rep. He was surprised the office was aware of the Big Dig.

Dik
 
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Quote from link above, translated by Chrome from German to English:

In 1933, a hangar collapses in Cottbus. Finsterwalder comes in custody, is interrogated and threatened with death penalty for sabotage. Since the inspection of the statics and construction confirms the perfect quality of the planning and execution, it [he] is released. One seeks and finds the error in the creeping of the concrete, the effects of which had not yet been taken into account in the state of the art [4].
 
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jrs87

Finterwalder, and the future engineers that learnt from his work, was very lucky. Remmember, that was nazi Germany.

An additional history fact, Freyssinet had already learnt about the effects of concrete creep when his Veurdre bridge (1910) starting sagging. At the time, he had to go at night with his trusted foreman to jack appart the three-hinge arch at the crown. Later on he built a test arch to study the effect of creep in concrete bridges. It was his knowledge of creep that allow him to develop a working concept of prestressed concrete. Previous developers did not fully meet the goal because of the creep, shrinkage and steel relaxation.
pont-le-veurdre1_ehzgo2.png


Live long and prosper
 
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jrs87,

Another name you should become familiar with is T.Y. Lin. By the way, those were some interesting lecture notes.

Here's a picture of T.Y. Lin's Ruck-a-Chucky bridge, arguably the most famous bridge never built.
RuckAChucky_xghnhh.jpg

Link
 
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The designs of Robert Maillart may provide some insight into best ways to approach concrete truss. It seems engineers in his time faced much more skepticism from the public than now. Perhaps the public now feels the government is watching out for them...

 
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Anyone speak Polish who can translate this? Illustrations look great, anchor at 11 is very interesting. No spiral confinement, no appreciable anchor steel reinforcement. Clean of concrete, a very explosive break. Anchor was to be designed by the PT supplier in the local zone behind the anchor so the plans showing nothing on this.


Regards,

Mojojohn
 
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3DDave said:
I expect that when tension was applied to #11 as part of the move it eased back on the crack and then when the post-tensioning was relieved the joint opened again; so they thought that re-applying the tension would close the crack.
Click to expand...
From report (after 2/6/18 inspection), the cross-sectional ~0.004" cracks on #3 and #10 appeared after #2 and #11 were stressed the first time (shoring still in place) - report said there were no other similar cracks.

The 2/28/18 report said #1/2 and #11/12 larger cracks appeared after shoring was removed, but before span was moved. This report was sent to Rodrigo Isaza at MCM and others, but not Denney Pate.. though it said "Forward to the EOR for their information. We will monitor these or any other developing cracks on the bridge, but we would like to the EOR to provide a response and determine if these were expected during the bridge stressing" so he should have gotten it.

From news, etc, it seems nothing was done, except to "wait and see" what happened after moving the span.

Pre-tensioning was relieved 10 days later, as scheduled, after moving the span (I agree cracks would get worse - from "jostling" during move and releasing #11 tension). Within a couple days Denney Pate left the phone msg to FDOT about the cracks which was retrieved Friday after collapse, but there was a mtg Thursday morning (assumed) to discuss the cracks with decision made to re-stress #11 to close them. The msg to FDOT was thought to be when cracks were first noticed, but the "leaked" photo/memo showed otherwise.

What happened actually proved ABC is better. The problem was seen before the span was moved. With span supported only under diaphragms (as in final position), there was opportunity to evaluate the cracks, de-stress #2 and #11 (as was planned after moving), and re-stress on side of road (attempt to close cracks). Also could have load tested in a safe place (though this would take more time and money). Had this design been used without ABC, the same thing would have happened, but there would have been no opportunity to deal with it away from traffic.
 
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MOJOJOHN (Structural) said:
Anyone speak Polish who can translate this?
Click to expand...
YouTube speaks Polish:
While viewing the video in your browser:
pause it
just to the right of the "like" and "dislike" thumbs; are three dots ...
click on the dots and select "open transcript" A box with the scrolling transcript will appear (will be in Polish).
Move your cursor to a blank area outside the box and Right click and select "Translate to English"
play... for me the on screen captions are now in English.

What a beautifully drawn and presented video!

Thank you for finding this

SF Charlie
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tkjohnson,

Re: Links

What is going on in Florida? Great finds.
 
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SFCharlie: thanks for the info. My computer (old laptop/windows7) wouldn't give the right click option for "translate to english" but I got through it and maybe this works (but I couldn't make it full screen).
THANKS MOJOJOHN! best I've seen and he did it with prelim specs.
 
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SF Charlie,
Thank you for the instructions on YouTube video translations. I didn't know you could do that.
Works very well for the most part. I like this translation though. Ha!

2018-06-04_11-35-43_twiriv.png
 
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Any ideas on what marking on this sensor may be? Also, what could have caused scorch marks?

P.S.

This video makes a point that MCM may have been faced with need to destroy span and restart and they could not face it. Can anyone cite a project that was destroyed and rebuilt as a precaution? I feel that the managers of any project MUST be prepared to abort. You can even test for this, but I will not go into that, use your imagination. The video is professional and excellent. Good find.

scorch_vsn8xs.jpg


 
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TheGreenLama (Structural) said:
Nothing new here. Just wanted to get a better picture of the FIGG design team. Denny Pate was the engineer of record, but others help craft this hybrid. Pate stamped the drawing. He's responsible. But it doesn't mean he designed the bridge. This was a team failure. These were cut from the "MCM FIGG Proposal for FIU Pedestrian Bridge," 9-30-2015
Click to expand...

Does anyone else think it seems odd that Ms. Figg is not licensed when she is in charge of the bridge engineering business. In fact, many of the players on the project are unlicensed so they don't have to worry about losing their licenses.
 
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More FIU Bridge background documentation, RFP etc
I think I saw some discussion of the RFP before, but I do not remember the images of "Examples of Signature Pedestrian Bridge Design Concept Precedents". Maybe I'm just being forgetful. I'm sure some are duplicates, so I apologize to any who's toes I've stepped on.

fiu-db-rfp-maxprice_draft_2014-06-24_final.pdf

FIU-Pedestrian-Bridge-Design-Criteria-2015-05-06_REV.pdf

white-house-honors-fiu-bridge-expert-as-champion-of-change

federal-grant-to-boost-universitycity-a-transportation-hub-at-fiu

building-bridges-to-the-white-house

chronicle-of-higher-education-engineer-connects-his-research-with-campus-bridge-project

fiu-to-develop-technology-to-fix-and-build-bridges-fast

UniversityCity_Project-Conceptual_Plans_2014-06_FINAL.pdf


SF Charlie
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