[quote=bdc0]When buying, getting something built with better building codes is good. Is there a time they changed a lot? If so, when? I tried Google, but no luck. I’m sure there are various minor changes, I’m thinking of something such as “two years after the xx earthquake, building codes were upgraded to require more [good stuff]”.[/quote]
I asked my husband (architect) and he said the big seismic building requirements happened in the early 70’s following a big earthquake in San Fernando Valley in 1971.
Our house was built in the 60’s… hubby has been going through, methodically, adding diagonal bracing, sheer walls (plywood replacing sheetrock), more bolts to the foundation and strapping. He’s a bit paranoid. LOL.
A little more digging since you asked for specifics.
1971 was the Sylmar earthquake in the San Fernando. It triggered changes in Hospital and School requirements (including retrofitting). It also triggered LA to go in and require retrofitting of masonry and brick buildings. http://www.bsc.ca.gov/abt_bsc/abt_hstry.htm
1994 was the Northridge earthquake – that triggered retrofit and new codes required for bridges and connecting structures (notice how the supports for freeway overpasses are now covered in steel.) It also changed the rules for wood framed structures 3 stories or higher. (More steel required if it’s 3 or more stories) http://en.wikipedia.org/wiki/1994_Northridge_earthquake
