Better 'before' an earthquake or fatigue failure. We've discussed these & other similar apps in the past & together w/ the incorporated stress sensor apps you pointed out, there are dual functions for many of these, incl use as cathodes/anodes to resist oxidation in any steel structure....bridges, buildings, oil pipelines, ships, offshore rigs etc. It's not as if there isn't a dire need for hi-tech solutions like these...w/ structural failures & rust issues to contend with: http://www.usatoday.com/story/money/business/2013/06/29/states-most-dangerous-bridges/2456467/
Yeah, my wife flew all over the country last year taking core samples from bridges which may have had unacceptable levels of chlorides in the post tensioning grout. It would be nice for her able to spend less time Inside bridge beams. Also, Berkeley is where she got her masters so we might be able to talk a friend I to going to that talk.