Bay Bridge rod troubles extend to base
 

"Ashton Crusher" > wrote in message
...
> On Fri, 17 May 2013 19:47:05 +0000 (UTC), "Leroy N. Soetoro"
> > wrote:
>
>>http://www.sfgate.com/bayarea/articl...les-extend-to-
>>base-4508623.php#photo-4610861
>>
>>The base of the new Bay Bridge eastern span's signature tower is secured
>>by more than 400 high-strength steel rods that were galvanized under
>>conditions Caltrans barred as putting them at risk of cracking, The
>>Chronicle has learned.
>>
>>The tower is the dominant feature of the $6.4 billion eastern span, which
>>is supposed to open over Labor Day weekend - a schedule that is now up in
>>the air because of problems with how the tower rods and nearly 2,000 other
>>steel fasteners were made.
>>
>>The 525-foot-tall tower has been the central feature of the span since
>>plans were drawn up in 1998. The landmark survived then-Gov. Arnold
>>Schwarzenegger's efforts in 2004 to scrap it due to cost and replace it
>>with a concrete causeway. In recent weeks the scaffolding has gradually
>>disappeared from around the tower, revealing the structure silhouetted on
>>the Golden State Warriors' uniforms.
>>
>>Not visible are the 424 threaded rods - 24 feet long and 3 and 4 inches in
>>diameter - that are among those Caltrans has belatedly realized are
>>vulnerable to being invaded by hydrogen that could cause them to become
>>brittle and crack.
>>
>>Caltrans can sample many of the 2,306 problematic steel rods on the span
>>in an effort to determine whether they will hold up. However, it cannot
>>easily inspect, remove or replace those that sit at the base of the tower
>>because the mammoth structure was lowered onto them in pieces.
>>
>>"We are aware of the issue," Caltrans spokesman Will Shuck said of the
>>tower rods. "These are going to get added scrutiny. We're going to make
>>100 percent sure they are safe."
>>
>>In an earthquake, the rods would perform a vital task - countering the
>>swaying forces on the tower. Caltrans officials say the rods are not being
>>subjected to a high stress load, which they say reduces the risk they
>>could crack.
>>
>>Some outside experts, however, said the way the tower rods were
>>manufactured makes them vulnerable to minor cracking that could suddenly
>>worsen in an earthquake.
>>
>>Problems in long run
>>
>>"The problem is going to be that, over a long time, you start to see some
>>cracks," said Russell Kane, an expert on metal embrittlement and corrosion
>>who owns a consulting firm in Texas. In an earthquake, he said, "you are
>>going to have some of those pre-existing cracks that are going to grow
>>like crazy."
>>
>>"If you have cracks in them, all bets are off," Kane said. "The thing
>>could be swaying in the wind very quickly."
>>
>>Like the other problematic steel rods on the eastern span, the ones at the
>>base of the tower were made to an industry standard known as A354 BD. That
>>denotes that the steel is of high strength and is allowed to be galvanized
>>- a process in which the rods are dipped in molten zinc, intended to keep
>>them from rusting.
>>
>>But federal and state highway officials have long warned against
>>galvanizing such high-strength steel and using it on bridges because of
>>the possibility it will fail.
>>
>>Galvanizing risk
>>
>>Galvanizing can seal in hydrogen, which can cause cracking. It can also
>>make it easier for hydrogen to invade the steel through flaws in the
>>coating, by way of an electro-chemical reaction.
>>
>>Caltrans banned such rods from bridges in 2000 because of the chance the
>>steel could become brittle during the galvanizing process. The agency made
>>an exception, however, for the A354 BD galvanized rods on the new Bay
>>Bridge - after instructing manufacturers to remove a step in the
>>galvanization process in which the metal is pickled in hydrochloric acid
>>before being dipped in zinc. They hoped that would minimize the risk of
>>hydrogen invasion.
>>
>>"Generic specifications are for a run-of-the-mill bridge," Caltrans
>>Director Malcolm Dougherty explained, "and this bridge is not run-of-the-
>>mill."
>>
>>In avoiding the acid baths, Caltrans was following the advice of the
>>American Society for Testing and Materials, an industry standards group
>>that establishes specifications.
>>
>>Failed rods
>>
>>Already, however, it's clear that Caltrans' precaution was far from
>>foolproof: In March, 32 of the rods on a seismic-stability structure on
>>the new eastern span snapped when they were tightened, even though they
>>had not been subjected to hydrochloric acid.
>>
>>Experts have speculated the destructive hydrogen could have come from
>>rainwater that filled the rods' holes after they were installed on the
>>bridge, although a committee of experts that Caltrans convened reported
>>last week that unspecified problems during galvanization were the "likely"
>>source of the contamination.
>>
>>The rods at the base of the tower, however, were subjected to the acid
>>baths, according to the company that supplied them in 2006 and 2007.
>>
>>Caltrans had specified that the rods should not get the acid treatment,
>>but somehow those instructions never made it to the galvanizer.
>>
>>Caltrans says it learned about the mistake during an audit it launched
>>last month into the bridge rods after it became clear there had been
>>problems in the manufacturing.
>>Amy Worth, chairwoman of the Metropolitan Transportation Commission, said
>>the apparent failure of Caltrans' quality control was alarming.
>>
>>"We're going to get to the bottom of it," said Worth, whose agency
>>oversees Caltrans' work on the bridge. "We want to figure out what
>>happened and then understand what the solution might be."
>>
>>Big danger
>>
>>Joseph Nicoletti, a veteran seismic engineer who until recently served on
>>a Bay Bridge advisory panel for Caltrans, said the potentially at-risk
>>rods serve a vital purpose - to check the shear forces in a quake.
>>
>>If they failed, he said, the tower could move horizontally. "That's
>>something you don't want," he said.
>>
>>Nicoletti speculated that the pitfalls of using galvanized high-strength
>>steel were not fully understood by the bridge's designers or Caltrans.
>>
>>"When you are doing a state-of-the-art job, you are playing with the state
>>of the art in metallurgy and everything else," he said. "I'm not surprised
>>something like this came up. Unfortunately, it came up at a bad time, and
>>at quite a cost."
>>
>>Records show the 424 tower rods were made by Vulcan Threaded Products in
>>Alabama, which received the order through the contractor that built the
>>tower, Kiewit-FCI-Manson joint venture, via two intermediary companies.
>>
>>Although the bid order that Caltrans issued in 2003 shows the rods were
>>supposed to be specially galvanized and not subjected to a hydrochloric
>>acid bath, a Vulcan executive said those instructions never made it to the
>>company.
>>
>>"We manufactured a quality product. We manufactured to the specifications
>>that they asked for," said Alan Logan, operations manager for Vulcan. "It
>>appears that they full-court-pressed us to get this material to them."
>>
>>Vulcan sent the rods to be galvanized by a Tennessee company, which
>>pickled them in hydrochloric acid before dipping them in molten zinc.
>>
>>No guarantees
>>
>>Logan said there was no guarantee the rods at the base of the tower won't
>>crack.
>>
>>"The problem is that nobody can say that," he said. "You really don't
>>know."
>>
>>Caltrans officials say they are trying to assess the vulnerability of the
>>tower's rods, but pointed out that they have already been inspected and
>>have been performing satisfactorily. "We're just not ready to make a
>>decision about them or any of the other rods until we have completed the
>>metallurgical analysis that is under way," said Caltrans spokesman Shuck.
>>
>>"If they need further study they're going to get it, because we're
>>absolutely going to deliver a safe bridge."
>>
>>But vouching for the rods will not be easy - removing one to be tested
>>would be all but impossible. They are embedded in concrete that rests atop
>>pilings driven deep into bedrock.
>>
>>One approach would be to sample their characteristics and try to assess
>>which among them might be the most vulnerable to cracking. "You ought to
>>be able to point to the ones that will be most at risk, and those are the
>>ones you would have to find a way to reinforce," corrosion expert Kane
>>said.
>>
>>The executive director of the transportation commission, Steve Heminger,
>>was not aware of any unusual quality control issues with the rods from
>>Vulcan.
>>
>>Governor optimistic
>>
>>"You have to examine what are the mechanical properties of those" rods,
>>Heminger said. "Based on my own experience on this bridge, Caltrans
>>quality control has been pretty rigorous," he said, adding that he is
>>especially curious to see what might have gone wrong.
>>
>>Ultimately, Heminger said, the decision on whether to open the bridge over
>>Labor Day weekend is likely to be made by elected officials, including
>>Gov. Jerry Brown.
>>
>>Brown told reporters last week that it was too early to "pull our hair
>>out" over the bridge problems and that he's optimistic everything will be
>>OK.
>>
>>"Don't know if it's a setback," the governor said. "I mean, look, s-
>>happens."
>
>
> This is far worse than they wish to admit because there is NO WAY they
> can ever be sure these rods will protect the bridge in an earthquake
> other then to have an earthquake and see if the bridge tower base
> shears. The problem is really two fold here... These were intended to
> prevent the base from shearing EVER, i.e. assuming any earthquakes
> were within the design range the bridge should have been able to
> withstand the quake and stay in service ready to take a hit from
> future quakes. Now it's likely that these rods will fail during the
> first quake that hits and while the bridge probably will remain
> standing the ability of the tower base to remain in service and
> withstand further quakes will be non-existent. The entire thing will
> have to be torn down and rebuilt.
>
> This is how this is going to play out now...
>
> 1- there will be an investigation and study
> 2- it will conclude that the structure, as currently constructed, will
> not fall down if a quake hits it.
> 3- some people will take the blame and get fired or promoted (you know
> how gvt works...)
> 4- the report will be waffly on whether the structure can withstand
> any future quakes.
> 5 - the private companies that should be responsible for the FULL cost
> of tearing down and rebuilding it to specs will be pretty much let off
> the hook - they will most likely pay millions in penalties, much of it
> paid not by them but by their bonding companies.
> 6 - All the private companies will point fingers at each other and
> threaten lawsuits. In the end their bonding companies and them will
> pay what they can afford to avoid litigation UNLESS the state truly
> pushes for FULL compensation for this fiasco.
> 7 - Most likely that won't happen because blaming gvt for failing to
> catch the mistakes OF THE CONTRACTOR, who is the RESPONSIBLE party, is
> always the politically expedient thing to do.
> 8 - In the end the state will get maybe 10% of what it will cost to
> fix this puppy sometime in the next 10 years after it's damaged due to
> the next big quake.
> 9- The contractors will walk away ****ed because this will eliminate
> their profits, raise their bonding costs for future projects. But
> they will have avoided having to cover the cost of their OWN ****up.
> 10 - The state people will have once again learned that it's always
> their fault.
> 11 - The big wigs will pat themselves on the back for their creative
> solutions to this problem and by the time the tower fails (5 to 10
> years from now) the people in charge will all be new faces who can't
> be blamed for what those people did "back then".
>
> This is The cycle of life for gvt contracting when things go wrong.

Sounds like a design problem to me. Apparently skipping the acid bath didn't
help the rods that cracked:

>>Failed rods
>>
>>Already, however, it's clear that Caltrans' precaution was far from
>>foolproof: In March, 32 of the rods on a seismic-stability structure on
>>the new eastern span snapped when they were tightened, even though they
>>had not been subjected to hydrochloric acid.