New Bay Bridge Steel Rod Issues Surface
FEATURE
“Steel rods that anchor the Bay Bridge eastern span’s massive main cable have shifted since they were installed and are now perilously close to sharp-edged plates inside the belly of the new bridge, a problem Caltrans acknowledges could take months and millions of dollars to fix,” the San Francisco Chronicle reports.
Engineers claim the rods “could be jerked in a major earthquake into those sharp edges, risking damage to the main cable and possibly threatening the bridge’s stability,” writes Jaxon Van Derbeken of the Chronicle.
The issue is the latest in a string of incidents involving connectors on the $6.4 billion Oakland Bay Bridge.
In March 2013, 32 rods broke shortly after being tensioned, prompting bridge officials to scramble for a fix for the rods, which were embedded in concrete. Hydrogen embrittlement was determined to be the cause. Testing on 2,200 bolts and rods “confirmed that the remaining rods…could fail prematurely.”
The latest problem surfaced when Caltrans inspected the more than 200 high-strength rods that hold both ends of the bridge’s nearly mile-long cable.
“Caltrans engineers don’t know for certain why the rods slipped out of position,” writes Van Derbeken. “One theory is that they were originally centered properly, but shifted when a temporary steel underpinning was removed.”
Caltrans does not believe the rods shifted over time because they were pulled too tightly to allow for movement, according to the Chronicle.
To address the issue, workers will attempt to loosen the rod nuts and recenter the fasteners.
“If that isn’t possible, workers will have to somehow widen the openings in 2-inch-thick steel plates to create more room for the rods to vibrate in a quake.”
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