OAKLAND — Strategically positioned high above the water, in a narrow crawl space between the new Bay Bridge deck and the top of its big pier east of the tower, instruments are listening for the sounds of cracking inside steel anchor rods.
Caltrans placed 10 acoustic emission sensors on select rods in early April after some of the massive bolts — 3 inches in diameter and 17 to 24 feet long — snapped and triggered widespread worry about the replacement eastern span’s seismic safety.
The instrument records the energy produced when a crack initiates, spreads or moves within the rod, said Caltrans materials engineer Bahjat Bagher, who showed off the testing late Friday. But so far, the rods being tested are quiet, a great relief to the agency.
If the bolts — fabricated in 2010, two years after the 32 bolts that broke — were also faulty and had to be replaced, the cost to make the $6.4 billion bridge safe for motorists would rise, and Caltrans would face an even greater hurdle to opening the bridge on time.
A second test for hardness is also showing favorable results, although a third saltwater corrosion test is still to come. (…)
via Bay Bridge technicians ‘listen’ for cracking in the steel anchor rods – San Jose Mercury News.