A place were I can write...

My simple blog of pictures of travel, friends, activities and the Universe we live in as we go slowly around the Sun.



October 01, 2014

Aptly named 'Slick Willy' Bay Bridge... Looks good but full of shit!

Latest defect: Bay Bridge tower rods sitting in water

By Jaxon Van Derbeken

Nearly every one of the 423 steel rods that anchor the tower of the new Bay Bridge eastern span to its base has been sitting in potentially corrosive water, Caltrans officials said Tuesday — one of the most serious construction defects found yet on the $6.4 billion project.

Several of the high-strength, 25-foot-long rods inspected after the first signs of trouble appeared last month were found to be submerged in several feet of water, in part because not enough grout had been pumped into protective sleeves to keep them dry, officials told members of a bridge project oversight committee in Oakland.

“I am a problem solver,” the bridge panel’s chairman, Steve Heminger, said after the meeting. “This is another problem — I certainly wish we would stop finding problems to solve.”

Six months before the bridge opened in September 2013, steel rods crucial to seismic-stabilizing structures on the bridge snapped when they were tensioned. On Tuesday, Caltrans revealed that rust and other signs of corrosion had been visible on those rods in 2011, but that no one had checked them further.

Engineering a fix to those rods cost bridge toll payers $25 million, and another $20 million has been spent on tests to determine whether additional rods and bolts are at risk of failing. Other problems have been revealed since the bridge opened, including leaks that threaten to spread rust through steel structures that support road decks on the suspension span.

'Not acceptable’
Caltrans officials are optimistic that the latest problem with rods in the tower won’t cause serious issues, but concede it should never have been a concern.

“It's not acceptable, and we’re going to fix it,” said Brian Maroney, Caltrans’ chief engineer on the bridge project.

Caltrans resident engineer Bill Casey said crews had found water on 95 percent of the rods at the base of the tower, in most cases “1 or 2 inches” deep in pockets between grout that surrounds the rods in their sleeves and caulk caps intended to keep the sleeves dry.

However, 17 rods were not properly filled with grout, including one that had only a foot of the protective material in the 15-foot sleeve, Casey said. Those rods were stewing in several gallons of water.

Caulking failure?
Maroney said one likely cause was that the caulking failed when the rods were tightened after being put in place.

The rods were installed by Kiewit Construction, which had the fabrication contract for the 525-foot-tall tower foundation. They were put in place before the structure was added beginning in 2010.

The source of the water found in the sleeves in recent days is not known. Maroney said the rod chamber had been flooded at least twice during storms, but officials have not ruled out the possibility that the water leached in from the bay.

That would be a bigger problem, because keeping bay water from finding its way into the sleeves would be far more difficult than keeping out rainwater. It could also mean water would be trapped below the grout, making it harder to remove.

Test results
Caltrans is testing the water both to determine its source and to look for zinc, which would be a sign that the rods are corroding. Results are expected as soon as this week.

It’s unclear how Caltrans would replace any corroded rods, because there’s no room in the chamber to maneuver new ones into position.

Maroney, however, said he was hopeful that because the rods were installed at a lower tension than those on the seismic structure, they won’t be as vulnerable to hydrogen that can lead to corrosion in high-strength steel.

On Tuesday, Caltrans revealed that a video inspection of the seismic-structure rods in August 2011 had found rust and other signs of corrosion. That was more than a year and a half before the rods were tightened and snapped.

In examining the rods’ sleeve holes in 2011, an inspector found “objects such as cigarette butts, U-bolts and wood chips,” along with standing water, a Caltrans summary said. The holes were drained, but more water apparently collected in the sleeves afterward, Caltrans said.

Surprise find
Higher-ups at the agency were unaware of the inspector’s report until earlier this year, when a video and photos of the damage were found on an engineer’s computer, said Tony Anziano, Caltrans’ toll bridge program manager.

“It should have been documented at the time,” Heminger, the bridge panel chairman, said after the meeting. “They should have taken additional steps to investigate whether the rods had been damaged.

That information, at the very least, should have been presented to us when we were in the middle of a full-scale investigation” into the rods’ failure.

“This is like they have the suspect in custody and they let him go,” Heminger said. “They were that close to that problem that blossomed a year or so later when those rods failed.”

He told Anziano, “This much strikes me as a pretty big fish that got away.”

“I understand your point,” Anziano said, adding that officials don’t know why they hadn’t learned earlier about the 2011 inspection.

Caltrans officials said the $20 million testing program that began after the rods failed has found no sign that the remaining 2,000 rods and bolts on the span are vulnerable to similar damage. Many are not at a high enough tension, and others are protected by paint, grease or dehumidifiers, they said.

The testing program is not expected to be finished until early next year, Caltrans said.

No comments:

Post a Comment

Note: Only a member of this blog may post a comment.