Bay Bridge news gets worse: Tower rod fails key test

A maintenance worker climbs a ladder to the base of the eastern Bay Bridge tower in February. New tests provide the strongest evidence yet that a steel rod that helps anchor the tower to its foundation is broken. less A maintenance worker climbs a ladder to the base of the eastern Bay Bridge tower in February. New tests provide the strongest evidence yet that a steel rod that helps anchor the tower to its foundation is ... more Photo: Paul Chinn / Paul Chinn / The Chronicle Buy photo Photo: Paul Chinn / Paul Chinn / The Chronicle Image 1 of / 58 Caption Close Bay Bridge news gets worse: Tower rod fails key test 1 / 58 Back to Gallery

One of the steel rods anchoring the tower of the new Bay Bridge eastern span has failed a key integrity test, suggesting it became corroded and broke during years when it was soaking in water, The Chronicle has learned.

The test result raises the possibility that hundreds of other rods that have been steeped in water in the bridge’s foundation in recent years are in danger of cracking, which could reduce the stability of the 525-foot-tall tower in a major earthquake.

State officials remained optimistic Thursday that corrosion was not to blame, and stressed that Caltrans isn’t certain of the rod’s condition because workers have not removed the 25-foot-long fastener from its sleeve.

Gareth Lacy, a spokesman for the state Transportation Agency, confirmed that the rod had failed what is called a mechanical pull test, in which crews tug on the fastener to see if it moves. If everything is right with the rod, it should stay in place. This rod moved during Wednesday’s test, Lacy said.

“They are investigating why one seismic rod at the base at the tower moved when it was pulled by the machine,” Lacy said. “It did not carry the expected load, and the next step is to remove it to fully investigate its condition.”

Downplaying corrosion

Dan McElhinney, the Caltrans district official overseeing the bridge project, downplayed the possibility that corrosion was to blame.

“We don't believe it’s corrosion — this bridge is not old enough for corrosion, not with these rods or under this level of loading,” he said.

“We need to know what else is going on,” McElhinney said. “It could take us one to two weeks to be able to remove it.”

He added that nearly all the remaining rods will now be pull tested to determine their integrity.

“The bridge is safe,” McElhinney said. “This is an important part of long-term maintenance of the bridge.”

Stewing in water

Nearly all of the tower’s 424 high-strength rods — intended to provide added seismic protection for the landmark structure — stewed in water for a prolonged period, exposing them to possible corrosion. A botched grouting and sealing job left hundreds of rod sleeves flooded, and recently Caltrans discovered signs indicating that salt water may be leaching into the foundation from the bay.

Although state officials hold out hope for an alternative explanation for the rod’s test failure, one outside expert said there was little doubt what happened.

“The thing clearly cracked,” said Lisa Fulton, a corrosion expert in Berkeley who has studied the problems on the span. “It means there’s little doubt that others are cracked — they just don’t know it. What are the odds this is the only one?”

Suspicions had centered on the rod after ultrasonic tests showed that it was 6 inches shorter than the others, a possible sign that it had broken at its base.

When workers for the bridge contractor pulled on the three rods, the shorter one gave way while the other two held fast, Lacy said.

Some bridge officials speculated that the rod was simply constructed shorter than other fasteners, for reasons unknown.

Bridge officials say they won’t know for sure what happened until the entire rod is removed. The rod has to be cut apart in 2-foot sections as it is pulled up, because there is not enough room at the base of the tower to remove an intact rod.

String of bad news

This is the latest bad news for Caltrans, which was rocked last week when tests on water found in three rod sleeves turned up elevated chloride levels — possible evidence of saltwater intrusion into the foundation. The bridge project’s oversight committee approved $400,000 to test more rod sleeves to see how widespread the problem is.

The chloride levels were about half what is normally found in salt water, Caltrans says. But they also were 50 times higher than what Caltrans found in water removed from rod sleeves last fall, when crews discovered that the bridge’s lead contractor had done an incomplete grouting and sealing job.

Experts say that if the rod that Caltrans is removing this week is indeed fractured, many of the other rods could be in jeopardy. There is precedent for that: Thirty-two similar steel rods failed on the bridge’s seismic-stabilizer structures in 2013 after they were exposed to rainwater for several years, forcing Caltrans to engineer a workaround that cost $45 million.

Foundation at risk?

Experts also fear that more than the rods could be endangered by salt water: The tower foundation itself could be at risk.

Salt can attack structural rebar embedded in concrete, and the rust can cause the steel to expand up to six times its original volume. That in turn can cause much worse cracks in the concrete. The rebar is covered with epoxy coating, but even that might not provide long-term protection, experts said.

Concrete shrinkage cracks were evident at the bottom of the foundation during construction, and crews injected them with epoxy, bridge officials say. But one expert said such concrete cracks can never be fully filled to guard against saltwater intrusion.

'All bets are off’

“If you have cracks, all bets are off,” said Russ Kane, a corrosion expert in Texas who has advised the military and offshore oil industry on how to recognize and combat corrosion.

Kane said salt water “does nothing good,” and corrodes steel roughly twice as fast as freshwater does.

“You have a situation where the long-term viability of this system is in question,” Kane said. “You have everything working against you at this point, and all the safety factors have been removed.”

Kane added, “After seeing everything else that has happened, it seems like more of the same. It shows kind of a wanton disregard for good engineering design and practice.”

Jaxon Van Derbeken is a San Francisco Chronicle staff writer. E-mail: jvanderbeken@sfchronicle.com