New Bay Bridge woes called 'maintenance'
Updated: 2014-06-04 09:09
By BONNIE WONG in San Francisco (China Daily USA)
205 out of 275 of the rods of the new Bay Bridge east span have misaligned with its steel plates. Bay Bridge Spokesperson Victor Gauthier says that maintenance is planned and the rods will not affect the seismic performance and safety of the bridge. Provided to China Daily.
Speculation about the stability of the new San Francisco Bay Bridge has risen again, this time over the steel rods that anchor the $6.5 billion bridge's eastern span that connects San Francisco to Oakland.
Out of the 274 rods that anchor the eastern end of the suspension span, 205 have misaligned since they were installed and are now hazardouslyclose to sharp-edged plates in the interior of the span. Engineers say a major earthquake could wrench the rods into the plates and damage them.
Some movement of the steel rods was anticipated, Bay Bridge spokesperson Victor Gauthier told China Daily.
"The exact location was really hard to find in terms of exactly where it was going to move," said Gauthier.
The original design left a 10mm buffer around the 90mm rod to allow for movement. However, with the misalignment of the rods off center, the buffer is no longer available and this can result in wear on the plates which the rods are threaded through.
Engineers are not sure why the rods slipped out of position, but plans are already in place for the rods to be repaired, although an exact date has yet to be decided.
Gauthier said that there are two options: Either jacking, or repositioning, the rods to the center of the holes they pass through, or carve out extra clearance through the holes.
Gauthier said that rather than a problem, the situation with the rods and plates is more one of maintenance. Gauthier also saidit would not affect how the bridge performed in an earthquake and the maintenance work would not interfere with commuters or traffics on a daily basis.
"It will take a couple of months," Gauthier said. "It is not something ongoing that will take several years."
Problems regarding the safety and dependability of the bridge have been surfacing even during the bridge's construction. Just before the opening of the bridge in September of 2013, the bolts of the bridge cracked as they were tightened toa third of the 96 rods used to secure seismic bracesto one section of the bridge. The manufacturer of the bolts, Shanghai Zhenhua Heavy Industry Co, came under fire for allegedly producing wrong-sized bolts.
Gauthier reiterated that the current issueis maintenance of the rods' alignment and is not due to any imported faulty materials. He also addressed the misconception that the new bridge was composed of solely China-made materials.
"We work with over eight countries around the world to make this bridge and more than 75 percent of the steel is from the US. The rods themselves are from the US and the steel plates are from Shanghai, China. We inspect these over and over again, we put these through a tremendous amount of tests and quality insurance and quality control before fabrication starts," said Gauthier.
Jeffery Heller, president of Heller Manus Architects and a member of the design advisory panel for the new bridge, said that maintenance is a necessary procedure.
"You can always hope that you do a perfect set of drawings and always hope that things get built perfectly, but in the real world, it never works that way. There will always be things that need to be corrected and you expect a certain amount of things that will have to be corrected as time goes on to adjust for the inevitable inability to create perfection," said Heller.
Heller does not think that the situation with the rods and the metal plates will affect the stability of the bridge and believes that the situation will be addressed without problem.
"The Bay Area got a great bridge and it will be a great bridge for hundreds of years," Heller said.