Second anchoring rod in San Francisco Bay Bridge fails key test

Reuters News
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Posted: May 28, 2015 8:37 PM

By Emmett Berg

SAN FRANCISCO (Reuters) - California transit officials have determined that a second high-strength steel anchoring rod for the eastern span of the San Francisco-Oakland Bay Bridge failed a key seismic "pull" test, and officials were due to meet on Thursday to address the issue.

The revelation by California's transportation agency came after officials said earlier this month that another steel rod, one of several hundred anchoring the bridge's tower, was broken, although Caltrans said at the time that the bridge should perform as designed in an earthquake.

A Bay Bridge oversight panel was expected to offer formal permission at a meeting on Thursday to pull the two 25-foot-long rods for visual inspection and possible transportation to a lab for analysis, said Leah Robinson-Leach, spokeswoman for Caltrans, the state department of transportation.

The panel “reserves the right to determine what will be done, how quickly and the cost allowed,” Robinson-Leach said. “The time, quality and ability to get the work done is a function of cost allowed.”

The eastern span of the bridge, which opened in 2013, is considered a self-anchoring bridge notable for its single white tower, which the National Basketball Association's Golden State Warriors have adopted for their logo.

The span was built, at a cost of $6.4 billion, to replace a multitower cantilever bridge built in 1936 that partially collapsed during the 6.9 magnitude Loma Prieta earthquake in 1989.

Caltrans said on Wednesday that an investigation begun in 2013 initially focused on high-strength steel bolts that had broken after prolonged exposure to water.

But that investigation later led to a probe into potential corrosion on the 424 anchor rods designed to keep the bridge tower in place in the event of a major Bay Area temblor.

“These anchor rods are one of the many seismic innovations on this bridge that help ensure resiliency of the structure for decades to come,” said Brian Maroney, chief engineer on the Bay Bridge project.

“The two rods that did not pass the test will be sent to a laboratory to determine exactly what happened to them,” he added.

(Reporting by Emmett Berg; Editing by Cynthia Johnston and Eric Beech)