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Old 04-18-2018, 08:25 PM   #161
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Re: FL Bridge Collapse


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Old 04-18-2018, 08:31 PM   #162
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Re: FL Bridge Collapse


Engineers are welcomed. Engineering is absolutey science.


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Old 04-18-2018, 08:32 PM   #163
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Re: FL Bridge Collapse


But is it contracting?
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Old 04-18-2018, 08:37 PM   #164
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Re: FL Bridge Collapse


I don't know why you wouldn't want guys like him hanging around if we let guys like me hang around.

I'm a professional, I pay the stupid bridge troll to get my stupid piece of paper and I do dumb stuff like paint basements for money... but don't we want to help expand the artform of the building trades through shared knowledge?

I feel like if his initial post is any indication that he's certainly within the "spirit" of the forum.
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Old 04-18-2018, 08:42 PM   #165
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Re: FL Bridge Collapse


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Engineering is absolutey science.
Sorry, we don't do absolutey science here.

This site is for guys who pick stuff up and move it.

Doctors sign contracts. Lawyers sign contracts. No doubt your wife the educator signs contracts, as does my wife the business analyst. None of those folks fit here.
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Old 04-18-2018, 09:21 PM   #166
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Re: FL Bridge Collapse


What about jaws, he's a truck ass we let him in!!!


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Old 04-18-2018, 09:28 PM   #167
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Re: FL Bridge Collapse


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What about jaws, he's a truck ass we let him in!!!


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Ive been doing a little truck assing lately . Not a ton of coin in it . But its easy on the spine.
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Old 04-19-2018, 07:31 AM   #168
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Re: FL Bridge Collapse


Truck ass has become such a great joke/mental image for me and the guys I work with that we actually love seeing it. Gives us something to joke about the rest of the day.
"You see, it's not good to keep starting and stopping the truck all the time. Wears out the engine. It's actually better for it to keep it idling in the driveway for six hours with the air conditioning running."


Anyways, I thought the guy made a solid first post which demonstrated a genuine interest in the building trades and he produced original content, which is the holy grail of the internet.
If it ever were to come to a vote, I'd vote let him stay.
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Old 04-19-2018, 07:37 AM   #169
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Re: FL Bridge Collapse


It's not a popularity contest.
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Old 04-19-2018, 07:58 AM   #170
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Re: FL Bridge Collapse


Quote:
Originally Posted by Californiadecks View Post
Engineers are welcomed. Engineering is absolutey science.


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No structural engineering is not. It is more guessing science. Srs you can google it. We have structural laws but they are guessing laws. You remember Millenium tower. They guess it will hold, footing didn't hold.
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Old 04-19-2018, 12:54 PM   #171
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Re: FL Bridge Collapse


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No structural engineering is not. It is more guessing science. Srs you can google it. We have structural laws but they are guessing laws. You remember Millenium tower. They guess it will hold, footing didn't hold.


I agree there are bad engineers. That why they carry malpractice insurance like doctors.


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Old 04-19-2018, 06:17 PM   #172
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Re: FL Bridge Collapse


IF you sell something, with a "contract" aren't you a "Contractor"?

Thus a consulting (licensed?) P>(rofessional = paid performer)E.(ngineer) or S.E. /Structural Engineer.

Full time teaching Engineer not a contractor....except with the college.....
Retired Eng. not a contractor....


Engineer in Training for A structural engineering firm that designs to contracts.....????

If you do something that speeds the plow of a building being constructed, to a written or verbal contract: you are a "contractor" IMHO.

Accountants, tax people, inspectors, deliverymen, supply chain, waste management, solid and semi-liquid....eeuh! design, labor, finishes, floors, roofs.......windows and doors, holes and walls, plumbing and electrical...

I can't build a large scaffold with an enclosure with out an Engineer's approval of the design....

Engineers sucked over 10% (1,200,000$) out that bridge that lasted 5 days in SweetWater Florida. Now that is contracting.
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Last edited by Fouthgeneration; 04-19-2018 at 06:22 PM.
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Old 04-21-2018, 08:57 AM   #173
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Re: FL Bridge Collapse


Final approved plans for construction from fdot :

https://cdn2.fdot.gov/fiu/13-Denney-...tion-plans.pdf
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Old 04-28-2018, 03:59 PM   #174
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Re: FL Bridge Collapse


From Leo....
"I can explain it to you, but I can't understand it for you."

I've already shown what happened, & I will now attempt to explain it....again.

It's about being between a rock, & a hard place......
#12 was the rock solid connection to deck, & #11 diagonal was the hard place. The short fillet block fillet was what stood between, & what ultimately failed.

#11 was 24 x 21 = 504 sq inch cross sectional area, at aprox 4,000psi load.

The fillet block that connected #11 to #12 was aprox 10 x 20 = 240 sq inches. at 2.1 x 4000 = 8000psi load.

Potentially the fillet block, is over 2.1 x the psi of #11.

If the bottom of #11, without fillet, was to travel .024" (.024"= 7 paper printer sheets), it would apply 8000 psi to the short fillet block. Becasue #11 to deck was a concrete construction joint, it would be normal for movement while the rebar took up a portion of the load.
So, in other words, .024" travel transfers 8000 psi to fillet block. Concrete fails at the rate .003"/inch, so .024" #11 travel = fillet failure.

In order for the fillet to be downsized to 1/2 #11, you would have to assume that the engineers figured that 1/2 of #11 energy would be transfered to the deck, WITHOUT MOVEMENT ACROSS DECK. I also have to wonder if they considered the block to be on a horizontal plane, & hence subject to the resulting horizontal force vector of the truss. If so, that was also a mistake. It doesn't become a horizontal force until it transfers to deck.
Again, here is what it would have looked like:

Last edited by Railman; 04-28-2018 at 06:28 PM.
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Old 04-28-2018, 04:15 PM   #175
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Re: FL Bridge Collapse


Said #11 to #12 fillet connection.
FL bridge collapse-fiu-number-11-12-horiz-small-3.jpg
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Old 05-08-2018, 01:52 PM   #176
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Re: FL Bridge Collapse


Here's the crack pict I was looking for. It would have allowed #11 to slide toward #12 needed amount for the fillet to explode. There are 3 different cracks in pict, so it may have been more complicated than I previously posted. In previous post I should'd have reduced force by about 25%, but that is still a very high psi on fillet.
FL bridge collapse-fiu-miami-herald-11-crack.jpg
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Old 05-08-2018, 02:33 PM   #177
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Re: FL Bridge Collapse


If the concrete didn't cure in tension, the steel would have had to deform to keep the crack open, unless I'm missing something.
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Old 06-02-2018, 12:43 PM   #178
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Re: FL Bridge Collapse


Preliminary report...
https://www.ntsb.gov/investigations/...009-prelim.pdf
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Old 06-02-2018, 12:57 PM   #179
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Re: FL Bridge Collapse


Sure is preliminary
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Old 06-02-2018, 03:45 PM   #180
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Re: FL Bridge Collapse


The blueprints(Plans for the youngsters/BIM) show only ONE set of confinement stirrups while I believe three sets are needed due to the three different directions the the concrete at the "nodes"/nexuses required 3 sets of confinement steel(carbon fiber or basalt might have been spec near salt water...).

Thus when all three tension vectors are combined, the design fails as the max load/difference/shear is exceeded.....

There was NOT enough steel rebar nor was the deck thick enough ( The ~16" thicken portion under the cross webs, which were 21" wide by 24" deep ( so the rebar box was only 17" wide by 20", with 2 or 4, 3.25" diameter post stress conduit tubes(many as yet ungrouted)) was further comprised with the ~ 9" deep recess to "Hide" the deck drain rain horizontal pipe.

The decision early on to hang the bridge from the structural components to reduce the elevator and stairway costs & lengths indirectly lead to the embedding the 8" drain pipe(it would have drained 30' x 185' of walkway) another straw(9" deep notch, 185' long) on this broken camel's back , note the center drain design reduced concrete thickness at the center line WHERE IT WAS needed the most.....
Add the 9,25" x 9.5" square deck drain opening less then 24" from the nexuses providing one MORE crack starting local ON EVERY ONE. to transfer the loads of the cross beams to the decks post tension cable, the concrete went into a tension mode and cracked apart.

Swiss cheese has fewer holes then the joints of this bridge did.

If the bottom joints had "tumors" of thicken concrete to distribute the stresses like the one added to the roof deck to attach the faux cable piping, the bridge might of went years before collapsing...

Furthermore, the silly angling of the cross beams to match the fake tension pipes, unnecessarily created a non-symmetrical loads which weakened and added costs, and appears to never have been checked design wise....

Mathematically constant angle cross webs would be MUCH simpler to model accurately....and avoid residual side thrusts with the least amount of material.... Form didn't follow function here.

What is the story behind the white coating? the Titanium Dioxide doped concrete didn't yield a white enough surface?

Railman @ 176:

Your picture shows the coating clearly. That crack starts at an unnecessary 90 degree stress riser built into the form work.... I'm thinking there is Zero steel bars bent around that inside angle.....
The truly scary part of that crack is the horizontal leg that appears to show the concrete has 100% separated at the deck level...
The bridge is already broken: No one has yet the balls to say so.

The accompanying photos show two cracks that parallel one of the PST cable conduits.

Just the fact the collapse was nearly instantaneous, points to brittle concrete in tension failure = inadequate steel load paths

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Last edited by Fouthgeneration; 06-02-2018 at 04:33 PM.
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