OAKLAND -- After 24 days of heavy load and a nasty saltwater bath, the first of four very large high-strength steel anchor rods similar to those that broke on the Bay Bridge earlier this year shows no sign of succumbing to the same fate.
If the trend holds, the bridge construction team won't anytime soon need to replace the hundreds of bolts in seismic stabilizers and rocker bearings next to those in which 32 out of 96 rods snapped in March. The defective bolts were made in 2008 while the others were made in 2010.
"There is a great deal of testing left to do, but it looks as though the 2008 rods were an anomaly," said John Fisher, an international steel expert, engineer and one of three members of the Toll Bridge Program Seismic Safety Peer Review Panel. He and his colleagues Friday visited the construction site, where they received a briefing on the testing.
The men also took a firsthand look at the temporary steel shims inserted into the rocker bearings last week, a move they pushed in July as a way to safely open the bridge to traffic as scheduled on Sept. 3 while the contractor completes repairs of the broken bolts.
Four anchor rods manufactured in 2010 and extracted from the new bridge are undergoing the special test designed to accelerate the effects of heavy loads and a marine environment, conditions that could lead to stress corrosion and failure.
The three agencies overseeing the bridge construction ordered the unprecedented testing in response to broad concerns about the quality of the 2,300 high-strength steel fasteners of varying sizes used on the new self-anchored suspension span. For the first four bolts undergoing testing, technicians are gradually increasing the load to 85 percent; they were under a 75 percent load while installed on the bridge.
The first rod has been under 85 percent load for five days with no sign of fracturing. The testing contractor was scheduled to increase the tension this weekend until it breaks and then begin examining the results, according to Toll Bridge Program Manager Tony Anziano. The remaining three bolts will follow the same testing pattern. Eventually, most of the 14 types of steel fasteners on the new span will be tested in a similar fashion.