"Not Our Problem"

IIRC a little under a year ago I started a thread here by saying how I'd
personally never trust epoxy to support the concrete ceiling panels in a
road tunnel, particularly when the glue was being applied by
construction workers under sometimes miserable weather conditions.
I posted that after a woman was killed in one of the recently completed
"Big Dig" tunnels here in Boston, when a concrete ceiling panel fell
down on the car she was a passenger in, with her husband right next to
her behind the wheel.
Yesterday, one year to the day after that tradgedy, the NTSB blamed
everybody involved and those everybodies all said "It was someone else's
fault, we didn't know that..."
No further comment by me required...Read all about it:
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Jeff
Reply to
Jeff Wisnia
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It's going to happen again and again. Duh ... how many of us would buy an epoxy garentied to hold up the ceiling fan?
Reply to
cncfixxer1
I'm a primitive, where the only thing I trust to work is welding, concrete, bolts, and properly trained workers. If one of the materials or the workers assembling them aren't what they should be, then all bets are off.
The key seems to be voids in the fast-set epoxy that allowed the bolts to deform. IIRC, there were over 200 affected bolt installations AND the problem had been noticed.
Graphic of NTSB conclusions
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Oh my god, the lawyers have been unleashed.
Jeff Wisnia wrote:
Reply to
Louis Ohland
There are so many ways to do things wrong and often only one way to do them right.
But it confirms my belief that quick set epoxy does not work as well as the slow set stuff.
Dan
Reply to
dcaster
Cheaper, faster path led to failure
"Overhead, the suspended ceiling has been ripped out and not replaced in the easternmost 250 feet of the tunnel because the area is already well ventilated. State engineers concluded the ceiling was never really necessary after all."
They could have used the much lighter steel ceiling panels, but they cost more. Some one was "Di-Di-Di" (thanks to Carlos Mencia) in thinking the concrete would save money when you factor in the PITA above head drilling necessary. I guess know they know better.
Louis Ohland wrote:
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Reply to
Louis Ohland
They shoulda used J-B Weld.
Bob Swinney
I'm a primitive, where the only thing I trust to work is welding, concrete, bolts, and properly trained workers. If one of the materials or the workers assembling them aren't what they should be, then all bets are off.
The key seems to be voids in the fast-set epoxy that allowed the bolts to deform. IIRC, there were over 200 affected bolt installations AND the problem had been noticed.
Graphic of NTSB conclusions
formatting link
Oh my god, the lawyers have been unleashed.
Jeff Wisnia wrote:
Reply to
Robert Swinney
That story just blames "bolts creeping out" and isn't as clear as the AP version. Sounds like the news writer was ignorant of the actual "creep" phenomenon and thought that bolts somehow unscrewed themselves.
The AP points to "creep", a specific material property which the engineers supposedly didn't account for. Creep is what sometimes (wrongly in my estimate) called "cold flow". The creep strength is much lower than tensile and compressive strengths, but in many applications doesn't matter. Apparently in this application it did. If that is the case, then it isn't a matter of shortcuts or flaws in the construction, it was wrong from the start in the design.
PTFE (Teflon) is the material most famous for creep. Until now I hadn't heard creep applied to epoxies.
Bolts are anchored in epoxy all the time. It's not an unreasonable thing to do. It just has to be properly done.
Reply to
Richard J Kinch
Usually refered to high temperature creep in the fast glass exprimantal aircraft industry.
Reply to
cavelamb himself
The engineers must have taken too much credence in that old Crazy glue commerial with the man suspended from his hard hat glued to a beam
Reply to
Tony
Let's see......
Ceiling panels falling down....
Millions of gallons of water leaking into the tunnels each month......likely eroding SOMETHING towards a future problem.....
Who wants to start a pool as to when some "brilliant" designer suggests building a "modern", up-to-date, overhead highway - devoid of all the problems associated with underground highways - above the current "Big Dig" ????
Five years?.....More?.....Less?
We could call it "The Southeast Ezpressway, II".......
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