Posted on 03/16/2018 12:25:26 PM PDT by C19fan
Engineering experts say investigators looking into the collapsed ‘instant’ bridge in Miami will want to know why a central tower which is usually built to support a suspension bridge was not in place when it collapsed onto Tamiami Trail on Thursday afternoon.
Last week, Florida International University’s official Twitter account posted a rendering of the bridge in its completed form as envisioned by the planners before its opening to foot traffic in early 2019.
The rendering shows a tall central column with cables connecting it to the main span.
Engineers say the design is known as a ‘cable-stayed bridge,’ which is a kind of suspension bridge, according to USA Today.
(Excerpt) Read more at dailymail.co.uk ...
Obviously the concrete had to “placed” in a form. The bridge wan’t formed in place on the support piers. What was done to eliminate the tension below the neutral axis to allow the bridge to be placed on the piers?
Can someone tell me why all of the news info is in Spanish & English? The Cubans have been there for decades. Their children & grandchildren (& great-grandchildren?) speak English as a first language.
What group of Spanish-speakers are they trying to reach?
Bridge built because lady died few years ago trying to cross street. Unreal.
Same here.
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Pre-calculator was log tables, not slide rules.
Slide rules were only an estimating tool.
Sounds like someone needs to practice asking “Would you like fries with that?”.
Virtue-signalling.
The opposing span was shorter and over water
Suspension tower should go in first
Opposing span second
Then the (now collapsed) span
Attaching cables, tensioning,
Then removing hydraulic supports
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>> “What group of Spanish-speakers are they trying to reach?” <<
Illegal alien voters!
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Meatloaf,
I think what e-s is trying to tell you is that you are probably confusing “post tensioning” with “pre-stressed” concrete beams, slabs or other structural elements.
What you see going down the highway are pre-stressed elements in most cases. They have been cured with an accelerated method, the internal cables and reinforcing were tensioned as the concrete was placed in the factory forms.
With Post Tensioned concrete slabs and other structural members, the tension is applied after the concrete is placed and begun its curing process to a certain point in its design strength curve.
In the former, any intentional camber is often formed into the member, and in the later it is possible for the tensioning itself to add some camber to the element I believe.
To add a little more confusion, there are two types of cables being discussed.
One is post tensioning cables with a slab or element section. The other types of cables notably absent are the large suspension cables swung from the central structural tower to structural connection point on the bridge box section that tie into the sloping “X” shapes between the lower deck and the upper structure that suspend the bridge in the “cable stayed”. If a tower was built and a full half, one side, was suspended by cables, it would obviously impose a great moment load on the tower pulling it over to one side.
Editor-Surveyor, if that was not your point, you are welcome to correct me.
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Right on!
So the muzzie developer who got an award from Obama is where?
Even though we are wasting $100 billion or more on a train nobody wants or will use, we can build a pretty good bridge for $15 million. One interesting thing about the bridge --> "The original plan for the bridge was to use concrete to keep costs down, but a steel design was chosen after the bids for a concrete bridge came in too high."
“The Tatars are the people who are native to Crimea and who have been historically savaged and slaughtered by the Russians.
“
And they make good sauce!
Usually this type of project is done through a joint venture between a contractor and an engineering/design firm.
I thought that was the greatest. I think that was freshman year, too (maybe sophomore). Learning about fundamental concepts like moment, shear, pinned connections, how to load a beam -- great stuff! I still remember modeling buckling with Euler's Buckling (or Critical) Load. At the time, all the names of people were new to me and I didn't realize how old some of the formulas were. Euler's formula was derived by him in 1757! Metallurgy, statics, thermodynamics -- they were all progressing rapidly during the Industrial Revolution.
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Exactly.
Post tensioning is what lifts the bridge off of the falsework and allows its removal. All camber is achieved after passing the design test targets.
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Regardless of the confusion, something whether rebar or cables allowed the lower structure of the concrete bridge to be moved to be placed on the piers. I suspect we understand the lower part of the bridge below what would have been the neutral axis cannot be allowed to be subjected to a tensile load. I believe that something happened after the bridge was in place that created a tensile loading leading to the collapse.
Did anyone else catch the name “Tamiami Trail”? Ring any bells?
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