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Bay Bridge inspections: busted bolts
SFGate.com ^ | 3/27/13 | Phillip Matier and Andrew Ross

Posted on 03/27/2013 9:25:11 AM PDT by NormsRevenge

At least 30 of the giant bolts that hold together the new, $6.4 billion eastern span of the Bay Bridge have snapped.

As a result, Caltrans is considering replacing all 288 of the bolts on the new bridge before it opens, The Chronicle has learned.

Caltrans insists the new span is safe and that plans to open it the day after Labor Day are still on track.

However, officials say it's too early to determine how long it will take to fix the problem - or the cost.

Toll Bridge Program Manager Tony Anziano said engineers are "pretty confident" the problem with the bolts is not a design issue or a construction problem but related to the quality of the steel bolts themselves.

"This isn't exotic - this isn't some wild issue," Anziano said.

Unlike the Chinese-built deck sections, the bolts - some as long 17 as feet - were produced in the United States.

"It appears to be a type of materials problem - the presence of hydrogen in the metal," he said. The hydrogen makes the metal brittle.

(Excerpt) Read more at sfgate.com ...


TOPICS: News/Current Events; US: California
KEYWORDS: baybridge; bolts; busted; caltrans; inspections; madeinchina
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To: Free in Texas
See Reply #13.

This poster claims it is sheer insanity to spend millions of dollars on bolts and not QC them.

21 posted on 03/27/2013 10:06:29 AM PDT by topher (Traditional values -- especially family values -- which have been proven over time.)
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To: NormsRevenge

Bolts made in China?


22 posted on 03/27/2013 10:11:01 AM PDT by tflabo (Truth or Tyranny)
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To: SWAMPSNIPER
They came loose because they were elongating beyond elastic limits or even breaking under tension.

Or thermal expansion. The longer a bolt is, the more it grows and shrinks in response to heating and cooling, and these were 17'.

23 posted on 03/27/2013 10:20:00 AM PDT by tacticalogic ("Oh, bother!" said Pooh, as he chambered his last round.)
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To: NormsRevenge
Unlike the Chinese-built deck sections, the bolts - some as long 17 as feet - were produced in the United States.

Sounds like in the former Soviet Union....

The nail factory made their quotas every year....

increasing the size of the nails....(big ones are easier to make)

Ended up with a huge pile of 50cm long nails that nobody brought.

24 posted on 03/27/2013 10:23:45 AM PDT by spokeshave (The only people better off today than 4 years ago are the Prisoners at Guantanamo.)
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To: topher
Hydrogen embrittlment usually comes from plating chrome or anti corrosion layers such as zinc or cadmium.

It is standard to bake the bolts at about 600f after plating to remove the hydrogen

May have been hard if they did not have a 18 foot long oven

25 posted on 03/27/2013 10:26:55 AM PDT by rdcbn
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To: DManA
Defective parts or defective design?

Can be both. However design of bolt- or rivet-connected bridge spans is a very well known process. Bridges of this type were built for more than a hundred years, entirely without computers; all you need is printed tables. Steel made in China, on the other hand, with no quality control and no incoming inspection, is a very likely culprit. An engineer doesn't claim that "the steel has too much hydrogen" until he has the lab test results in hand.

A comment above mentions that some bolts were loose. If the holes are too large this can result in uneven loading of bolts - and then indeed some will be sheared off, and then the rest follows. If the bolts are not tight then they will experience axial stress instead of shear stress, and the thread will be torn off. It's all very obvious when you look at the bolt, and the guys who are investigating are usually experienced troubleshooters.

26 posted on 03/27/2013 10:38:56 AM PDT by Greysard
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To: NormsRevenge
Caltrans insists the new span is safe...

I still distantly miss the beaches once in a great, great while.

27 posted on 03/27/2013 10:43:11 AM PDT by Standing Wolf
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To: NormsRevenge

About seven years ago, the oil field went through a period of buying Chinese drill pipe. Failure after failure after failure.


28 posted on 03/27/2013 10:44:46 AM PDT by razorback-bert (I'm in shape. Round is a shape isn't it?)
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To: yarddog

ASTM specs.


29 posted on 03/27/2013 10:47:09 AM PDT by Cobra64 (Common sense isn't common anymore.)
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To: rdcbn

Not that hard to contract out. Friend of mine works in a place with an industrial oven several hundred feet long.


30 posted on 03/27/2013 10:49:26 AM PDT by Hillarys Gate Cult (Liberals make unrealistic demands on reality and reality doesn't oblige them.)
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To: topher

When you torque a bolt, even the toughest alloy, it stretches almost like a rubber band. It has to hold that state of tension without elongating beyond a certain point and loosening, or breaking, and it must hold this property over time. Design involves choosing the proper material for the expected load but sometimes the best calculations fail in practice.


31 posted on 03/27/2013 10:58:41 AM PDT by SWAMPSNIPER (The Second Amendment, a Matter of Fact, Not a Matter of Opinion)
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To: NormsRevenge
♫ Look for the Union Label ♫
32 posted on 03/27/2013 11:02:52 AM PDT by BobL (Look up "CSCOPE" if you want to see something really scary)
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To: NormsRevenge

The problem in California is not the bolts, it’s the nuts.


33 posted on 03/27/2013 11:05:31 AM PDT by reg45 (Barack 0bama: Implementing class warfare by having no class.)
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To: SWAMPSNIPER
Then the design must allow for some of the bolts to fail and the rest to be able to handle the load.

Considering what happened with the Nimitz Freeway pancaking during an earthquake, going above-and-beyond should be done in a place like San Francisco.

The reference to the pancaking of the Freeway was that the freeway had two layers. The earthquake caused the top layer to come down on the bottom layer. Some folks were crushed in their cars as a result, as I recall.

34 posted on 03/27/2013 11:09:14 AM PDT by topher (Traditional values -- especially family values -- which have been proven over time.)
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To: topher

They will all fail, given time. You can extend the time but it will affect other considerations, appearance, cost, etc.


35 posted on 03/27/2013 11:20:55 AM PDT by SWAMPSNIPER (The Second Amendment, a Matter of Fact, Not a Matter of Opinion)
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To: Greysard

You could, and should, do a simple nondestructive hardness test on the material being used to make the bolts before the bolts are made and before any other test are done.

You could do a hardness test on enough material to make 288+ bolts in about 2 days max.

That would tell you if the material is up to specs before wasting any more time or money on it.

Too soft or too hard chunk it.

No point in spending any more time or money making a bolt when it’s going to be junk anyway.


36 posted on 03/27/2013 11:21:39 AM PDT by IMR 4350
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To: NormsRevenge

You have to understand that this is a Cal Trans project, and Cal Trans is one of the most incompetent organizations within the State of California.

Several years ago in Orange County on a major freeway interchange where Cal Trans was in charge of constructing freeway “flyover” ramps, they discovered at a very late stage that the pre-stressed concrete was below acceptable quality. Initially they thought that the entire set of flyover ramps would have to be torn down. They finally found a way to “rework” them but it took nearly two years to do so.

In the case of this bridge, there was no excuse for both the general contractor and Cal Trans to have strength tests run on those bolts as well as all major steel components. But what the hay, this is California, and that just about says it all these days.


37 posted on 03/27/2013 11:22:46 AM PDT by CdMGuy
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To: razorback-bert

In the 70’s and 80’s it was American steel that was junk.

In one job alone I rejected over 1 million feet of 2 3/8” tubing.


38 posted on 03/27/2013 11:34:33 AM PDT by IMR 4350
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To: RinaseaofDs

When I’m “pretty sure”, and I often am, I check.


39 posted on 03/27/2013 11:41:43 AM PDT by Flash Bazbeaux
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To: topher
This is not even the stress of an earthquake causing these problems, and as someone mentioned, the bridge is supposed to withstand an 8.5 magnitude quake...

The GG Bridge was built in the early 1930's. In the 1980's, for the 50th year celebration, they allowed a mass of people to walk the bridge, completely filling it with people (jammed together weighing much more than any load of vehicular traffic). The bridge flattened out from it's arch but everything held together, and engineers were able to relax from their fear of a collapse (politicians wanted the people walk). That's 1930's U.S. steel! Nowadays, replacement steel pieces regularly break on the Oakland side of the Bay Bridge, some having damaged cars. Part of the reason for the new section.

40 posted on 03/27/2013 11:49:27 AM PDT by roadcat
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