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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. |
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