3/17/15, "Tests of Bay Bridge rods find more widespread cracking," SF Chronicle, Jaxon Van Derbeken
"Tests on one of the high-strength steel rods that secure the base of the tower of the new Bay Bridge eastern span show more widespread cracking than Caltrans officials had previously acknowledged, The Chronicle has learned.
Rust and microscopic cracking were found after one of 424 fasteners intended to keep the tower from being damaged in an earthquake was removed for testing last year. The problems were found on the lower part of the rod, which became flooded because of a botched grouting and caulking job during construction— a mistake that resulted in many of the 25-foot-long fasteners stewing in water for several years.
But test program documents reviewed by The Chronicle indicate that cracks were also found at the top, where the rod had been under stress but had not been soaking in water. The discovery is a troubling development for Caltrans because such cracks can get worse over time, leading to total failure, possibly during a quake.
“They saw something there,” said Bill Casey, the bridge project’s resident engineer, referring to flaws detected at the top of the rod. “They need to do the full investigation to see what it really is.”
Litany of problems
Widespread cracking would be only the latest problem for the high-strength galvanized-steel rods that anchor the tower. Caltrans has acknowledged they were put at greater risk of cracking during processing, suffered damage in shipment, were left standing in corrosive water and then put under heightened stress when the tower was pulled back to keep it from leaning toward Oakland.
“You are almost afraid to look around the next corner — there’s so many things being piled on top of each other here that all go the wrong direction,” said Russ Kane, a corrosion expert who has advised the military and oil industry. “You ask yourself, what can go wrong next?”
Although Caltrans officials say more tests need to be done — at a cost of several million dollars — there is little money left to perform them. The $6.4 billion project is running in the red, with an expected deficit of at least $10 million
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The tests are needed to identify just why the test rod is cracking, Caltrans says. One suspect is hydrogen, which can invade high-strength steel that is exposed to water. That was the culprit, officials believe, in the March 2013 failure of 32 rods on the new span’s seismic stabilizer structures.
Complicating matters is that it is impossible to remove any of the 424 tower rods without cutting them up and destroying them. With the 525-foot tower now in place, it is also impossible to maneuver replacements into position.
Mystery cause
Hydrogen, however, may not explain the cracking, especially since the top of the test rod was not in water. Brian Maroney, chief engineer on the project, said cracking in the absence of water could point to other factors, including heightened stress and manufacturing problems.
About half the tower rods were put under significantly added stress in 2011, Maroney noted, when crews jacked the tower back to keep it from listing about 18 inches toward Oakland.
One outside expert, however, said he doubted that stress alone or manufacturing issues led to the cracking. He said water is the likely culprit.
Charles McMahon, a professor emeritus at the University of Pennsylvania and an expert on steel embrittlement, said the photos he has seen point to hydrogen.
“This is hydrogen-induced cracking,” he said. Even a small amount of water exposure at the top of the rods could be enough to cause micro-cracking in material that is highly susceptible to hydrogen-induced failure, McMahon said.
“It’s pretty clear that the guys who were in charge of this thing are clueless when it comes to selecting the right materials,” McMahon said. “They had no idea what they were doing. The whole thing is a disaster.”
Fateful choice
The problem can be traced to Caltrans’ decision in 2003 to ignore its own rules against using high-strength galvanized-steel rods and bolts on bridges when it came to construction of the eastern span.
Galvanization — a process by which the rods are coated with molten zinc — has long been understood as a threat to high-strength steel. The process carries the risk the rods can be exposed to hydrogen.
Caltrans decided, however, that the extraordinary seismic demands placed on the eastern span because of its unusual self-anchored design required the use of such high-strength steel. They specified precautions to avoid hydrogen contamination during processing.
After the 2013 failures, however, Caltrans learned it had no record of overseeing the manufacturing process or testing the tower rods before they were installed.
'Pretty amazing’
Will Kempton, a former head of Caltrans who now serves on the bridge’s oversight panel — composed of the current heads of Caltrans and local and state transportation authorities — said at a recent meeting that such a breakdown in oversight was “pretty amazing to me.”
“This is the first time in my career where we didn’t have any construction records,” said Caltrans head Malcolm Dougherty. “So it is definitely an outlier.”
When it delved into what records were available, Caltrans learned that the tower rods had been bathed in hydrochloric acid before being delivered to the bridge, a method the agency specified against because of the fear it could expose the rods to hydrogen.
The agency’s records also raised another red flag — the rods were scraped en route from the Tennessee plant where they were galvanized in 2007. At a stopover in Texas, workers spray-painted the scrapes and other damage to the galvanization layer. Any damage to the threads from the scrapes could foster cracking, experts say.
Money tight
Money is proving to be a problem in the search for a cause of the cracks. Nearly all $6 million set aside for testing on the project this budget year is gone. The oversight panel suggested that Caltrans look to cut costs elsewhere on the bridge project, paid for entirely by toll payers, to finance more tests on the rods.
“We’ve got a construction budget that’s under severe stress,” said Steve Heminger, the executive director of the Metropolitan Transportation Commission.
Maroney said that for now, testing is at a standstill. Caltrans can’t even conduct ultrasonic tests that could reveal whether one of the tower rods has already snapped. Casey said Caltrans officials are taking a “timeout.”
“We have a little bit more work than we have money for,” he said."
Image caption: "Eastern section of new Bay Bridge, next to the old span, contains fractured anchor rods. Photo by Michael Macor, San Francisco Chronicle"
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