Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Bay Bridge Broken Bolts

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Hi Harold,

Here is some info on "Bay Bridge Broken Bolts". All the info is in public domain and almost entirely comes from Caltrans : -Some info can be found here: http://baybridgeinfo.org/rods , for general public and press -The most detailed information so far for engineers, that is in public domain, is here:http://www.dot.ca.gov/hq/paffairs/AnchorRods/ -These were A354 BD hot-dip galvanized anchor rods (not bolts) connecting the shear keys on the east end of the new SAS Bay Bridge to top of the R/C pier. - The failed anchor rods were 3" in diameter. The length of anchor rods vary from 9 to 24ft. -The 32 that fractured about a week or so after tightening, were from 2008 batch manufactured by Dyson in Ohio. There is another 2010 batch.
-According to Caltrans, the cause is due to hydrogen embrittlement
-According to Caltrans there are about 2000 of these A354 BD galvanized anchor rods and threaded rods in the SAS bridge and some in the Richmond San Rafael Bridge .

Best

Hassan Astaneh (www.ce.berkeley.edu/~astaneh)

On 5/11/2013 2:27 PM, Harold Sprague wrote:
What is the inside information on the Bay Bridge bolts?

What I have been able to learn is that:

The bolts specified were ASTM A354 BD, hot dipped galvanized.
30% of the bolts manufactured in 2010 fractured during the tensioning
operation. The fractures were attributed to hydrogen embrittlement.
There are procedures to investigate and mitigate for hydrogen
embrittlement.  It is unknown if these were specified. The ASTM A 354
cautions about hydrogen embrittlement for galvanizing the BD bolt.

Several entities have chosen to use high strength molibdenum bolts to avoid galvanizing and obtain corrosion resistance.

I am just kicking this out for discussion.

Regards, Harold Sprague

--
Abolhassan Astaneh, Ph.D., P.E., Professor
Department of Civil and Env. Engineering
781 Davis Hall, MC 1710
University of California,
Berkeley, CA  94720-1710,  USA

web: www.ce.berkeley.edu/~astaneh  and www.astaneh.net

-------------------------------------------------------------------------
Post your message to the list by sending it to: SEAINT-SEAOSC(--nospam--at)mail-list.com.

The email messages sent to the list will be saved in an archive on the World Wide Web.
These archives are located at:
   http://archive.mail-list.com/SEAINT-SEAOSC

To contact the list owner, send your message to:
  SEAINT-SEAOSC-list-owner(--nospam--at)mail-list.com.

Sponsored By: Pacific Structural & Forensic Engineers Group, Inc. (PSFEG)

To unsubscribe, switch to/from digest, get on/off vacation, or change your email address, click here.
<http://cgi.mail-list.com/u?ln=seaint-seaosc&nm=seaintma%40euken.net>