I35W bridge

Date 08-02-2007 15:44

Looking at the photos that have been published on Brazilian newspapers it seems to me that it was a concrete bridge, not structural steel. Am I right?
Giovanni S. Crisi
Sao Paulo - Brazil

By chall

Date 08-02-2007 15:49

There is a photo of the bridge under construction in 1967 here:

http://www.foxnews.com/photoessay/0,4644,2152,00.html#40_2145

It looks like a steel girder construction.

Charles

By jwright650 (*****)

Date 08-02-2007 15:56

http://kstp.com/article/stories/S106209.shtml?cat=1

Live coverage on channel 5 in MN.

By 357max

Date 08-02-2007 16:00

It has a steel super structure with concrete decking.

By ssbn727 (*****)

Date 08-02-2007 16:43

And it was rated a 50 out of a possible 120 or depending on who's doing the rating, a 4 out of a possible 10 regarding the level of structural deficiencies found during the last inspection in 2006.

Btw Giovanni, the bridge next to the one that collapsed is a concrete bridge :)

Finally, the bridge that collapsed was scheduled to be replaced not repaired, in 2020!!!
Kind of makes you wonder how many other bridges in the US might need some rather accelerated replacement if the number of bridges with similar ratings in structural deficiencies are around 80 thousand!!!

Estimates are just that, and nowadays we tend to rely too heavily on estimates which mostly tend to be way off these days - a word to the wise!!!

Respectfully,
Henry

By G.S.Crisi (****)

Date 08-03-2007 15:16

You're right, gentlemen, yesterday night I saw the collapsing scenes on the television and it was clear that it was a structural steel bridge. Only the pillars are concrete.
Giovanni S. Crisi

By 357max

Date 08-03-2007 16:32

Weldors, the bridge expert news media is starting to beat on welding. News coverage last night blabbed/babbled that the welding wasn't as good in '67 as it is today. They didn't mention electroslag but I'm sure they were alluding to it.

By reddoggoose (**)

Date 08-03-2007 18:02

Now I don't think I quite agree with the remark that welding wasn't as good in '67 as it is today (not that the news media knows anything about it). Though the welding industry has progressed regarding the quality and selection of available welding processes, consumables and electrodes that we have today, there is more to the equation. I don't think the general skill level for welders in this country is what it once was. Granted I wasn't even born in '67, but I know welders who were earning a living in 67' by burnin' rods, my grandfather included. Seems these days people turn up their noses at the thought of welding. It's like welding has become a four letter word, not to mention how there is an increasing number of high schools and tech schools dropping their welding programs. Seems to me maybe, as a nation we should be investing more resources into trades like welding. As our countries infrastructure ages more things like bridges, pipelines and buildings are going to need maintained or replaced, and thats not something that can be shipped over to China to be worked on for a .03 cent/hour wage. Oh well enough of my ranting, hope I didn't high jack the thread.

By jwright650 (*****)

Date 08-03-2007 18:24

You know you mentioned that you can't have bridges built in China or somewhere and then erected over here...well, I know of a few companies that do exactly that. I watch a presentation given by a very well known welding consultant to one of those companies and he showed slides of the bridge sections being welding in close tolerance frames/jigs and then shipped on barges over here and tugs towing them upstream in major rivers to where the old bridges are coming down and the new spans are being hoisted up into place directly off the barges.

By cwf07

Date 08-04-2007 02:08

i weld on bridges in ga and i work with other welder that were welding on bridges before i was born and i was born in 1967 i have learn a lot form them. they say the only that has change is that the state is going more concrete and they change the way we beam splice.but over all they are strict on us welder in ga. we have to retest every year.

By chall

Date 08-03-2007 18:11

I listened to the press conference during which the State Chief Engineer for bridges talked about advances in understanding of welding issues.

His point was that when the bridge was designed and built, fatigue issues were not considered with the same significance as they are today. Furthermore, the effects of low temperatures are weighed more heavily today than back in the early to mid 60s. Aslo, the Fracture Critical program was brought about after this bridge was designed and built, so obviously advances in understanding were made between then and now.

I didn't get the impression that he was making any kind of value statement on the quality of welding; however, others in the media may be assuming that is what he was getting at.

Charles.

By Kix

Date 08-03-2007 19:07 Edited 08-06-2007 13:43

I just want to know what happened to cause a bridge like that to come down the way it did. Must of had a couple hundred welds bust all at once to bring that sucker straight down like it did (yeah right). Something gave out and my money is not on the welding. Very sad to see inocent people go down like that. I couldn't imagine being trapped in you car under water with a 2' steel I beam in the windshield. I've been working around heavy steel construction like that for years and to see what it takes to move I beams like the ones used on the bridge around and then to see it all twisted and mangled like that just makes you scratch your head and say wow.

By chall

Date 08-04-2007 01:54

I agree with you completely. My comments were drected at the perception that "someone may be attempting to hang this on - bad wlelding".

By CWI555

Date 08-04-2007 06:20

Performing an armchair analysis, my money is on the following:

It's not any one factor but rather a combination of errors. Corrosion, Weld cracking, and Pin cracking.
Several weld stress cracks were in the report, however; the key word is stress cracks. What initiated the stress to begin with, why was the crack monitored rather than fixed, the same goes for the corrosion and cracking of the pins, and corrosion of other key elements. Vibration harmonics may also have played a roll in this. Get the previously listed conditions put together with a harmonic vibration of the right cycle and pop. I also believe the welds were good to begin with. A bridge of that size, used with the frequency it's used, in the environment it's in will eventually have a problem regardless of the quality of the initial welds. The best weld in the world cannot substitute or hold up bad engineering, and subsequent bad data on the risk based analysis. This business of "monitoring" crack growth as mentioned in the reports is to me insane. They let known cracks in FCM's stand because they were "monitoring them for growth". I don't claim to be an engineer, but I think that's pushing the limits of the statistical model value. The MnDOT put off inspection while waiting for surface work to complete knowing this as well.

In short, I think someone really screwed the pooch on the analysis of the bridges safety. I would venture to say the decision to let it go was an economical one based on risk analysis, in which they rolled the dice and this time came up snake eyes.

As for the remainder of what fell, the whole thing was a system. When part of that system failed dramatically, the rest dominoed. That is pretty clear to one and all.

By Tommyjoking (****)

Date 08-04-2007 08:11

I agree completely with you Gerald:

Unfortanately I am also very convinced that this is one of many being treated in the same fashion. I actually think some persons should be held accountable maybe even for manslaughter.....There was on obvious problem but somone('s) did not make the hard $$ decision (dont forget that being rerouted on your commute everyday for a few years makes it hard to get elected in some cases...you know the typical this sux I will point the finger at somone cause it makes me feel better thing that seems to be the beast of public conciousness). Well people died and some have thier lives forever changed ...and guess what they got to rebuild it anyway!!! Yes I hope an ambulance chaser or two will also seek criminal charges in the case because negligence does not even begin to describe the situation. Its just a terribly sad state of affairs.

Failure: All metal is going to give out with flex and vibration eventually period....a good design and quality work makes that failure much more predictable as far as time goes. Just look at some of Boeing's real world tests of the 777 wing structure....amazing predictability of failure within a given set of stress cycles. No different with a bridge or any other structure for that matter. That bridge was designed/built with a certain amount of use (traffic) in mind ....I am sure that those expectations were much exceeded going into the late eighties and into today. Any of you old enough to remember when you seen maybe 5 cars an hour on a country two lane? Now how many do you see? No different with the Interstate .....growth exceeds capacity on almost all our roads. But one thing is clear...obvious serious defects were observed and they rolled the dice just as Gerald stated. Stress fractures grow and sometimes they can grow explosively ....

Say a prayer for those involved in all this they do need it.

Regards
Tommy

By TimGary (****)

Date 08-06-2007 14:29

There was a bridge across the TN river, in West TN, that collapsed during initial construction about 15 years ago. They had installed the 3 main girders that spanned the river and were making adjustments when the whole thing started to ripple and eventually collapsed. Over 6 million dollars worth of work gone. The two guys who were making the adjustments were killed. The contractor blamed the engineering, the engineering blamed the contractor etc. etc. When the blame game was all over with, the collapse was finally blamed on the two workers making the adjustmets. They'll probably blame the Minnesota collapse on the resurfacing crew...

Tim

By HgTX

Date 08-06-2007 19:23

It doesn't take a couple hundred welds to bust all at once. All it takes is one, if it's the right (or wrong) one. That bridge was very nonredundant; there were a lot of fracture-critical members, meaning if that member goes the bridge comes down. One busted weld, one initial material flaw, one pier undermined by scour, one something. The 1967 collapse of the Silver Bridge was traced to one itty-bitty flaw in one eyebar.

Hg

By cwf07

Date 08-04-2007 01:49

i heard it was stress and rust i also heard bad design

By johnnyh (***)

Date 08-04-2007 19:55

The bridge in minnesota was under constuction at the time of the collapse so i am sure the engineers of that project will face heavy scrutiny. The TX DOT released what bridges had the worst ratings in texas and sure enough the one with the worst rating is just up the road from where i live. It is a truss bridge also that was built in 1939. It is scheduled to be replaced soon. It has a big dip in the middle and makes hella noise when a big truck drives through. Hopefully it will be replaced before tragedy strikes. My prayers go out to the survivors and families of all involved up north.

By gshuma

Date 08-06-2007 13:05

Are any of you guys old enough to remember the Kansas City Hyatt?

By CWI555

Date 08-06-2007 14:05

Yes.

By gshuma

Date 08-06-2007 15:58

The Hyatt walkway fell and killed and injured a lot of people. It was welded per the engineer but last minute design changes were made to facilitate installation.
A failure seldom has only 1 cause.

By CWI555

Date 08-06-2007 18:33

It was also inspected in 1 hour. People on the site had questioned it, people in the office drinking hot coffee poo pooed it and said it was good.
http://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse

By gshuma

Date 08-06-2007 23:50

Hey thanks
I only remember reading the trade mags of that time.

By devo

Date 08-07-2007 13:31

Just a week before the I-35 bridge collapse I got done reading "To Engineer is Human" by Henry Petroski. It Illustrates the role of failure in engineering structures, and how those failures often do more to advance knowledge than the successes do. Among the many salient points made by the author was the responsibility of all involved to be honest and open with regards to failure investigation. As the investigation into the Hyatt Regency collapse was beginning, a third, undamaged walkway of similar design in the hotel was dismantled in the middle of the night by hotel management, citing "safety issues". This greatly hindered the efforts of investigators to determine the exact cause of the failure. I hope there is not a race between the state DOT, the designers, and the contractors to cover their own asses. But the book is a wonderful read, easily understood by a layman like myself, and offers great insight into the nature of engineering.