Caltrans Prepares For Massive Repair Job On Cracked Seismic Bolts
OAKLAND (KCBS) - Caltrans is preparing to test the integrity of seismic sheer bolts on the new eastern span of the Bay Bridge as crews prepare for a massive repair job where dozens of those bolts have already cracked, officials said Friday.
Twenty workers on a platform underneath the skyway of the new span drilled into its eastern pier Thursday so that massive steel saddles could be installed over seismic safety devices known as sheer keys.
"It does exactly the same thing the bolts did," said engineer William Casey, explaining the $10 million fix to members of the media offered a firsthand look at the repairs.
Caltrans Prepares For Massive Repair Job On Cracked Seismic Bolts
"The bolts are no longer useful, so we're putting a saddle over the top," he said, "a U-shaped saddle that goes over the top and pulls the whole sheer key base right down."
Casey said the saddles and the bolts will prevent the eastern span from excessive swaying during a major quake.
Caltrans spokesman Andrew Gordon said the saddles are still being fabricated, so it remains unclear whether crews will be able to finish installing them before the bridge's scheduled opening on Labor Day.
The other factor that could delay the bridge's opening, tests on 192 bolts manufactured by the same company two years after it delivered the defective bolts, also has an uncertain timeframe, Gordon said.
To test their integrity, a section of each bolt must be submerged in salt water and tensioned over a prolonged time period to test how quickly the metal corrodes, Gordon said.
"That will tell us ultimately how long these 2010 bolts will last out in the field," he said.
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