The new eastern span of the Bay Bridge has had a long history of problems:
Pier E-2 of the eastern section of the new bay Bridge which contains the fractured anchor rods, as CalTrans conducts a boat tour of the impacted areas of the bridge on Wednesday Mar. 27, 2013, in Oakland, Ca. Caltrans disclosed that more than a third of the 96 rods used to seismically strengthen the span near Yerba Buena Island had snapped when workers tightened the nuts used to hold them in place.
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.
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.”
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?”
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