On March 1, 2013, workers began tensioning the 96 ASTM A354 Grade BD rods fabricated in 2008 for two of the East Span’s four shear keys. Shortly after that, it was discovered that 32 of the 96 rods had fractured. Engineers and metallurgists determined the bolts had cracked due to hydrogen embrittlement (HE), which occurs when excess hydrogen, a susceptible material, and tension are present.Last fall, Caltrans bridge inspectors found that more than 400 high-strength steel rods imbedded in the SAS tower’s foundation were not sealed properly, which failed to protect them from the environment. The anchor rods became the focus of attention when Caltrans discovered they were ineffectively grouted by the contractor and sitting in standing water. The threads of one rod stripped through its bottom nut and failed, prompting a thorough investigation of all the rods.
See Failed Anchor Rods on the San Francisco-Oakland Bay Bridge: A Corrosion Discussion by Norm Moriber and Kathy Riggs Larsen, 11/2/2015, Materials Performance Magazine.
I predict we will find at least one engineer onsite at the time of the in-place post-tensioning in this event. Ultimately, the key likely will be which entity was represented by that engineer force.
Trackhoe with jack hammer attachment just demolished the leaning portion of the bridge and it collapsed in a big cloud of dust. Fire department spraying debris to settle dust while trackhoe operator takes a break.
http://miami.cbslocal.com/video/channel/316-live-video/