Bay Bridge troubles began with design
Jaxon Van Derbeken | San Francisco Chronicle
Updated 8:52 am, Sunday, June 23, 2013
The team designing the new Bay Bridge eastern span had a problem.Pressure was building to move forward on what would become the most expensive public works project in California history, but Caltrans' in-house steel experts reviewing plans for the new bridge had spotted what they believed was a major flaw.
Among the more than 1,000 pages, they pointed to a single sheet that called for the use of a particular type of high-strength steel bolt coated in molten zinc, a process known as galvanization. Such bolts, the experts warned, were prone to cracking in a moist marine environment such as San Francisco Bay and shouldn't be used.
It turned out that the bridge design called for thousands of other bolts and rods made of that same kind of steel - fasteners strong enough to enable the unconventional span to resist the everyday vibrations created by big rigs and the far stronger forces unleashed in a large earthquake.
In a flurry of deadline-driven decisions over the next few weeks in early 2003, the design team from the firm T.Y. Lin International and Caltrans officials made adjustments in response to the experts' warnings. But they also took their cue from a bolt manufacturer - which said Caltrans had used the same kind of steel on an earlier, high-profile bridge project - and opted to install more than 2,300 galvanized, hardened fasteners on the eastern span.
It's a decision that haunts Caltrans 10 years later, now that the failure of 32 high-strength rods has raised fundamental questions about the bridge's integrity and threatens the eastern span's already long-overdue opening.
"They felt they had adequately addressed the concerns," Richard Land, a Caltrans deputy director who recently took control of the project, said of the officials who made the crucial decisions a decade ago.
In hindsight, he said, the effort "wasn't as complete as it should have been."
Drawing up a plan
Caltrans' first instinct after the 1989 Loma Prieta earthquake knocked out a section of the eastern span was to consider a retrofit. But review panels concluded that building a new bridge would be safer and cheaper, so in 1997, the agency turned to T.Y. Lin International.
Founded by visionary civil engineer Tung-Yen Lin in 1954, the San Francisco firm had more than 1,000 engineers, planners and architects who designed huge projects such as airports and long-span bridges. Its range was such that it submitted two completely different designs for a new eastern span to international experts judging a competition for the state.
The more conventional approach relied on slender cables stretching out from a central tower. The other ran smaller strands off giant cables that were draped over a tower, then wrapped around and underneath the deck.
That became known as the self-anchored suspension span. Its fans did not include Lin himself, who several years earlier had sold the company that bore his name. He hated the design, calling it too expensive and cumbersome.
"This will be building a monument to stupidity," Lin said when a design panel overrode his objections and selected the self-anchored suspension span in 1998.
Under the gun
T.Y. Lin International sent its final design plans to Caltrans for review in November 2002. Time was not on the state agency's side.
Political bickering had already set the project back years. Caltrans officials said during groundbreaking in early 2002 that the new bridge would be open by 2007, which would beat the 20th anniversary of Loma Prieta by just two years.
And by the end of 2002, Caltrans was in financial chaos.
It ran out of money for highway projects in December because of state budget problems. Projects involving earthquake safety - such as the eastern span - were still being funded. But there were no guarantees that would last, and everyone was eager to start bidding on the first phase of the suspension span, the steel-and-concrete foundation of the signature tower.
Always looming, Land said, was "a significant political urgency to getting this job under way and completed."
Experts find problems
As part of the design's vetting, Caltrans gave T.Y. Lin International's work to its structural steel committee - a group of the agency's most trusted and veteran bridge engineers and design experts. The review panel issued its report Jan. 10, 2003, 11 days before the contract for the tower's foundation was to be put out for bid.
Although many of the engineers involved in the bridge project would not discuss what happened next, e-mails and other documents released by Caltrans help fill in the picture.
The panel's chairman, bridge engineer Lian Duan, zeroed in on one aspect of the design in particular - the bolts that were to bind steel parts together inside concrete beams, which would sit atop the bridge's columns and support the road decks.
The bolts - known under the industrial classification of A490 - were to be made of high-strength steel and galvanized.
The problem was that galvanizing bolts carried a danger: Hydrogen, in rainwater, saltwater mist or fog, could be absorbed through gaps in the layer of zinc and, by way of an electro-chemical reaction, make the hardened steel brittle.
Duan, who had taught structural engineering and edited bridge design and structural engineering manuals, told Caltrans officials that such bolts were "not appropriate" in a marine environment and advised T.Y. Lin International to "consider other materials."
Duan also asked how the bridge builders were going to protect similar rods and bolts, known under the industry classification of A354 BD. They were longer and thicker than A490 bolts, but were otherwise metallurgically identical.
T.Y. Lin International was planning to use more than 2,300 of those rods and bolts to anchor the tower and bind giant seismic stabilizers to the concrete below them and the road deck above.
The firm believed that only hardened steel could handle the lateral forces expected in a major quake. The bridge's unique, asymmetrical design was an issue: It meant some parts of the span would have to bear more of a burden than similar components on a bridge with a symmetrical design.
Already rejected
Other members of the review panel shared Duan's concerns. Martin Pohll, a bridge engineer who has since left Caltrans, said in an interview that the same experts had rejected both A490 and A354 BD galvanized, high-strength bolts in a seismic retrofit of the Bay Bridge's western span just months earlier.
"The marine environment is pretty corrosive - that's why it takes all kinds of things to make sure (bridges) are going to be there for years," Pohll said. "We knew we had some locations with high-strength bolts that they were trying to galvanize. We didn't use them."
Caltrans bridge expert Eugene Thimmhardy, another panel member, said there was never any question when it came to galvanizing the type of bolts Duan had identified.
"It was categorically no, each and every time," he said. "Stay away from galvanized."
T.Y. Lin International's lead designer on the project, Marwan Nader, took the expert panel's advice and abandoned plans to galvanize the type of bolts that had worried Duan. However, the fate of the metallurgically identical A354 BD rods and bolts was still unresolved.
Caltrans had specifically banned such steel fasteners on bridges three years earlier because of the risk they could crack.
In a Feb. 28 response to the panel's concerns, Nader told Caltrans that T.Y. Lin International and state bridge engineers were "looking into" what to do.
It was not a small question. Using other materials could mean months of re-engineering, and a likelihood that Caltrans would miss its newly rescheduled opening date of 2009.
Supplier's solution
Two weeks later, a bolt maker offered up a solution to Nader's - and Caltrans' - dilemma.
Dyson Corp., based in Painesville, Ohio, had made bolts and rods for the original Bay Bridge in the 1930s. It was one of the few companies in the country that specialized in giant steel fasteners, for use on everything from nuclear power plants to Navy ships.
On March 13, 2003, the company's sales manager, Kristin Wolf, faxed three pages of Caltrans documents to an engineer at T.Y. Lin International.
She pointed out that the paperwork showed that Caltrans had approved high-strength, galvanized rods in its 2001 retrofit of the Richmond-San Rafael Bridge - the same type of fasteners that T.Y. Lin International was now proposing be used on the eastern span's tower and elsewhere.
Wolf had good reason to have that knowledge at her fingertips - Dyson had supplied 772 of the Richmond-San Rafael Bridge bolts.
Caltrans had tried to keep those bolts from cracking by ordering Dyson to blast the steel with grit during the galvanizing process instead of pickling it in hydrochloric acid.
Either approach would clean the steel before it was galvanized. But the acid also contains destructive hydrogen that can later attack the metal.
Caltrans agrees
Five days later, on March 18, one of Nader's colleagues at T.Y. Lin International, Associate Vice President Jim Rucker, told Caltrans that "Dyson Corp. has followed this procedure for thousands" of A354 BD rods and bolts on other projects.
"Is this acceptable" for the new Bay Bridge? Rucker asked.
Caltrans' senior bridge engineer, Steve Margaris, took up the question with Rob Reis, the agency's corrosion expert. Reis responded that Dyson's suggestion could work, but cautioned that Caltrans should conduct special bending tests on the rods when they arrived to make sure they had not become brittle during processing.
On April 3, a Caltrans senior engineer, Robert Kobal, declared in an e-mail that the Dyson suggestion "does the trick."
T.Y. Lin International's design could proceed, high-strength rods and all. Dyson ended up supplying more than 1,800 hardened, galvanized rods and bolts for the eastern span.
Kobal made his proclamation after checking with an engineer on the Richmond-San Rafael Bridge project who reported that the high-strength rods and bolts had passed the normal battery of tests and shown "no problems."
It turned out, however, that those steel fasteners were kept at much lower tension levels than what T.Y. Lin International planned for many uses on the eastern span. Ratcheting up the tension would increase the chances that a brittle bolt could crack.
As for the committee of experts' warning about the susceptibility of galvanized, high-strength steel: Caltrans "blew us off," Pohll said. "I don't think we were kept in the loop of the design process."
Land, the Caltrans deputy director, agreed that his engineers had failed to account for the risk that A354 BD fasteners could fail once they were put in a marine environment. "There's no evidence to show that was part of the conversation," he said.
Problems emerge
Not long after Caltrans developed bid specifications for the rods, trouble began.
In 2008, the first batch of Dyson rods failed five out of 14 tests for ductility, suggesting there could be brittleness problems. Caltrans told the bridge's main contractor, American Bridge/Fluor, that it should make sure such problems "will not arise in the future" - and then Caltrans accepted the batch of 96 rods.
The rods were soon installed in holes in a concrete beam, awaiting the installation of two giant seismic boxes called shear keys. They were left to bask in the elements for five years, with crews periodically blasting out the hydrogen-rich rainwater that collected in the holes.
The only company to provide bolts and rods for the eastern span besides Dyson, Vulcan Threaded Products of Alabama, never got the message that the high-strength rods should not be bathed in hydrochloric acid. It supplied 424 hardened steel fasteners for the tower.
Caltrans can't check the rods for brittleness now because they are embedded under the 525-foot structure. They were left out in the air for years, but the agency says the rods are at lower tension and now in a dry environment, protecting them from destructive hydrogen.
The special bending tests that Caltrans intended to conduct on all the rods and bolts to check for brittleness were never performed. Caltrans officials said such tests were not practical.
But Land, the Caltrans deputy who now oversees the eastern span project, said he was "concerned that tests were asked for and we don't see test results submitted."
Companies balk
Caltrans solicited other steel-fastener manufacturers in bidding rounds in 2008 and in 2010, but two main Dyson competitors - Portland Bolt and Haydon Bolts - refused to take part.
Making such high-strength, galvanized steel rods for a bridge "was just something we weren't comfortable with doing," said Dane McKinnon, who oversees purchasing and certification for Portland Bolt. "The potential for hydrogen embrittlement was there."
McKinnon said Haydon executives had told him they declined to bid for the same reason. Those executives did not respond to requests for comment.
Portland Bolt didn't simply refuse to bid. Soon after Caltrans solicited its business, the company posted a warning on its website of the perils of using high-strength, galvanized rods and bolts.
"We're trying to educate people," McKinnon said. "We get asked all the time to do that - it's something we have chosen not to do."
Land said Caltrans' inability to attract bidders should have sounded alarm bells. "I'd be concerned if I heard that suppliers didn't bid because of the risk," he said.
Public finds out
In March, everyone learned the upshot of the decisions Caltrans made a decade earlier.
When workers tightened the 96 rods from Dyson's first batch on the shear keys, 32 of them cracked. A cascade of revelations followed, jeopardizing plans for the eastern span's grand opening - which by now had slipped to Labor Day weekend, nearly 24 years after Loma Prieta. Caltrans says it will decide by July 10 whether the bridge will open then or perhaps months later.
"I don't know the whole history of how they dropped the ball, but it looks like they did," said Pohll, the onetime member of the panel of expert bridge engineers.
He still has faith the agency he served for more than two decades will find a solution.
"They have a lot of smart people," Pohll said. "Once they know about a problem, they are going to be on board to make sure it's fixed."
Bridge-bolts timeline
Events leading up to Caltrans' acceptance of cracking-prone steel fasteners for the new Bay Bridge eastern span.
1997: T.Y. Lin International draws up two different plans for a new eastern span.
1998: The state picks a self-anchored, asymmetrical design - requiring thousands of high-strength rods and bolts to bind its components so the span can withstand road deck vibration and earthquakes.
January 2000: Caltrans bars the use of all galvanized, high-strength bolts on bridges, saying the process of dipping the fasteners in molten zinc to protect them from rust makes them prone to being invaded by hydrogen, which can make them crack.
Nov. 27, 2002: T.Y. Lin International submits its design for Caltrans expert review. The plan calls for thousands of bolts of the type Caltrans had banned from being galvanized.
Jan. 10, 2003: Caltrans panel of experts says some galvanized bolts included in the design are "not appropriate" in a marine environment, and raises corrosion concerns about thousands of other fasteners.
March 13, 2003: Dyson Corp., a supplier of bolts, points out that Caltrans accepted high-strength, galvanized steel fasteners - specially treated to avoid hydrogen-caused embrittlement - on the Richmond San Rafael Bridge retrofit in 2001.
March 18, 2003: T.Y. Lin International asks Caltrans if it will accept the Richmond Bridge-style bolts on the eastern span.
April 3, 2003: A Caltrans senior engineer says there have been "no problems" with the Richmond Bridge rods, and that the Dyson method "does the trick" on the eastern span.
Source: http://www.sfgate.com/bayarea/article/Bay-Bridge-troubles-began-with-design-4616774.php
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