Minneapolis Bridge Failure Report Due out Soon
Minneapolis Bridge Failure Report Due out Soon
(OP)
To all..
I understand that preliminary details have been released about this long awaited report.
As I understand it, structural gusset plates were undersized (or marginal) and the strength of the corroded plate was not adequate for the load.
Also, (as I understand it) there will again be an argument as to who is responsible for the final review and approval of structural details.
Anyone remember the cause of the Hyatt Regency walkway collapse in 1981 (Kansas City, MO)? ...114 people DEAD..!!!
The investigators found a structural detail that was done by someone who was incompetent.
http://en .wikipedia .org/wiki/ Hyatt_Rege ncy_walkwa y_collapse
Deja Vu all over again ???
My opinion only...
-MJC
I understand that preliminary details have been released about this long awaited report.
As I understand it, structural gusset plates were undersized (or marginal) and the strength of the corroded plate was not adequate for the load.
Also, (as I understand it) there will again be an argument as to who is responsible for the final review and approval of structural details.
Anyone remember the cause of the Hyatt Regency walkway collapse in 1981 (Kansas City, MO)? ...114 people DEAD..!!!
The investigators found a structural detail that was done by someone who was incompetent.
http://en
Deja Vu all over again ???
My opinion only...
-MJC





RE: Minneapolis Bridge Failure Report Due out Soon
I'm not sure I see the point in figuring out who screwed up 50 years ago; they're probably dead and almost certainly no longer practicing.
Hg
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RE: Minneapolis Bridge Failure Report Due out Soon
Our Missouri PE dues about doubled to pay for the lawsuit aginst him!! Never understood that??
RE: Minneapolis Bridge Failure Report Due out Soon
Once again, the Minneapolis bridge matter is much more complicated than a plates not meeting an allowable stress. Heck the bridge stood for 40 years and the last twenty with more load and heavier traffic than it was designed to carry.
I just hate to see engineering diasters trivialized in a few sentences. That hardly makes us look good to the public, if we can't agree amoungst ourselves that these matters are typically more complicated.
Let's not throw the profession down the toilet because we feel compelled to make some comments on a website.
Regards,
![[pipe] pipe](https://www.tipmaster.com/images/pipe.gif)
Qshake
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RE: Minneapolis Bridge Failure Report Due out Soon
The report on the bridge should also give clarity, but enough has been released that we know that gusset plates were undersized in key areas. Whether calculation error or drafting error, unchecked, we may never know. Human error.
RE: Minneapolis Bridge Failure Report Due out Soon
Again, I only asked....is it "Deja Vu all over again" ???
Qshake, can you better quantify "more load and heavier traffic than it was designed to carry"
I am not a bridge designer, so please excuse my questions, "How is it possible to overload a highway bridge with traffic only..?? Only so many trucks/cars will fit on the bridge ?
Was it the temporary loads of construction materials that were being stored by the contractor that pushed the bridge over the edge ?
-MJC
RE: Minneapolis Bridge Failure Report Due out Soon
I'm not exactly sure what you are asking. Deja Vu seems more like a statement than a question.
RE: Minneapolis Bridge Failure Report Due out Soon
And as for the plates being too small, the max load of the bridge was increased. (How much I don't know but it has been increased.) As engineers how can we see what people and (the goverment) are going to use what we desgine in 20, 30, 40 or 50 years from now? We make our best assumes at the time and hope for the best and then tell the world the max load, current, preassure, or aanything else that our system can do.
Chris
"In this house, we obey the laws of thermodynamics." Homer Simpson
RE: Minneapolis Bridge Failure Report Due out Soon
From the reports, this bridge is about 1500' long and about 90' wide. The concrete bridge deck was increased from 6.5" to 8.5~9". This alone is 2100 tons of additional dead load. In addition, the reports show that two additional lanes were added in or about 1998.
Now think back to the era of the sixities and seventies where labor was cheap and material was at a premium. Bridges (like airplanes) are designed to carry the most payload (traffic in this case) with the least self weight, they are optimized in other words. You cannot simply throw additional load on a bridge and not check members and more importantly connections.
Today it is different as material is cheaper than the labor producing it. So it may be hard to imagine the scenario I suggest above.
Moreover, our traffic has gradually increased in weight from the 1960s. To see this, check out the design codes for bridges, AASHTO, and see if we didn't start out with H15 then HS20 and now we're designing interstate bridges for HS25. Railroads are moving to heavier loads too. So essentially you have two additional lanes than what was originally designed for and more dead load and heavier traffic composition.
And as I noted, the biggest problem we face is engineers casting this matter off with the wave of a hand with the idea that thin gusset plates and only thin gusset plates are responsible. This is irresponsible and confuses the public who rely on engineers for life safety.
Regards,
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Qshake
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RE: Minneapolis Bridge Failure Report Due out Soon
RE: Minneapolis Bridge Failure Report Due out Soon
Regards,
![[pipe] pipe](https://www.tipmaster.com/images/pipe.gif)
Qshake
Eng-Tips Forums:Real Solutions for Real Problems Really Quick.
RE: Minneapolis Bridge Failure Report Due out Soon
RE: Minneapolis Bridge Failure Report Due out Soon
Moreover, I've seen many DOT personnel rant against prices for analysis and complain that such and such doesn't need to be done....I hope this practice is coming to an end. And I hope that whatever or whoever created such suspicion in the owners minds will not do so again.
Regards,
![[pipe] pipe](https://www.tipmaster.com/images/pipe.gif)
Qshake
Eng-Tips Forums:Real Solutions for Real Problems Really Quick.
RE: Minneapolis Bridge Failure Report Due out Soon
Qshake, you stated "the biggest problem we face is engineers casting this matter off with the wave of a hand"
Fundamentally, isn't this what happened at the Hyatt Regency ?
WRT the Hyatt disaster, I have read up extensively on the "structural detail" that was marginal, at best, on the steel detail drawings, then changed and approved by the engineer of record.
For those of you who did not understand my quote in the first post, "Deja Vu all over again" refers to a well known and very humorous statement by Yogi Berra, one of the greatest (but unintentional)US humorists.....
JAE,...The definition of "deja vu is here:
http://www.thefreedictionary.com/deja+vu
-MJC
RE: Minneapolis Bridge Failure Report Due out Soon
RE: Minneapolis Bridge Failure Report Due out Soon
In the walkway collapse, the underlying flaw was essentially in the culture of buildings project development within the structural community. At the time, the culture there in Missouri was that steel fabricators designed connections and the EOR simply specified the intent of the connection. Jack Gilliam's firm sent the drawings off to the contractor who sent them to a fabricator who started the shops and the design but never finished them. The first fabricator farmed out that job to another fabricator due to workload and the new fabricator incorrectly assumed that the connections had been designed. Upon shop drawing review, Gilliam's firm didn't review them intently, again assuming that the design had been accomplished by the fabricator. The change in rod from one to two didn't help but that is simply one of many details that got by everyone due to the culture of farming out the connection design.
In the Minneapolis bridge collapse, I don't see the failure as a similar cultural thing but rather one of a simple design error in calculation, or perhaps a drafting error. The "cultural" aspect of this could perhaps be that of an insufficient QC process originally, and also what Qshake suggests above that the long term review of bridges made some assumptions that allowed the gusset situation to go unnoticed for years.
I sat at a conference some years ago where Ed Phrang, the NBS engineer who reported on the Hyatt collapse, stated that "we engineers need to remember that our structures are not beams and columns connected together. Rather, they are a multitude of connections linked by beams and columns."
Qshakes statement that so much software is "beam and column" oriented vs. "connection" oriented is right on the money.
RE: Minneapolis Bridge Failure Report Due out Soon
Re: the bridge, let's wait for the full report.
-
Syl.
RE: Minneapolis Bridge Failure Report Due out Soon
As well as the undetected error in the shop drawing stage, there was design error.
The National Bureau of Standards tested the connection of the hanger rods going through the boxed channels, and determined that the ultimate capacity of the originally specified connection was only about 60% of the required capacity.
So the failure probably would not have occurred if either the original design had been adequate or if the change had not been made. Both contributed, and there was no redundancy, so the tragedy occurred.
RE: Minneapolis Bridge Failure Report Due out Soon
However, Gilliam, in a later talk I attended, stated that the "intent" of what everyone called the "original design" was that they were just indicating a concept and not designing the connection in any way shape or form.
He said that, upon coming to the site that night his first words were, "where are the stiffners?". He saw that the rod nuts had just pulled through the channel flange-tip welds and understood right away that the final "design" was flawed.
RE: Minneapolis Bridge Failure Report Due out Soon
RE: Minneapolis Bridge Failure Report Due out Soon
But my earlier point was that the culture of design at the time (back in mid 1970's) was that the EOR did not do connection designs.
I think for what it's worth, the Hyatt Regency Collapse at least moved the US structural design practice away from fabricator designs (at least with unique connections). For standard beam to beam or beam to column connections we still see fabricators doing the design in many parts of the country.
RE: Minneapolis Bridge Failure Report Due out Soon
The one I have most concern about here in Australia is delegating the design of the "flatwork", usually post-tensioned slabs, to others. The post-tensioning contractor then hires his own engineers, and there is too much separation between the base building engineer and the subcontractor's engineer. There are other examples.
RE: Minneapolis Bridge Failure Report Due out Soon
As a structural engineer who is in the major bridge industry I tend to see this as very closed minded and the public deserves better from the scientific process and how a multitude of factors acted in concert to produce the results on a single day, certain time.
And no, I'm not suggesting we start looking for the alien beings from Area 51!!
Regards,
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Qshake
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