L.A. Earthquake Retrofit Bill

[Lee L.]

The L.A. City Council may soon pass major legislation to force owners of certain apartment buildings to retrofit their properties for earthquakes. According to the L.A. Times, the legislation may affect 13,500 wooden buildings and 1,500 "brittle apartment buildings." The cost of such retrofits would be "$60,000 to $130,000 for wooden apartment buildings and millions of dollars for taller concrete buildings." (LA Times, October 7, 2015). 

As for the wooden buildings, the legislation aims to target "soft story" buildings, commonly those with garages or commercial buildings on the first floor. 

 I'm curious if there is a database that lists the soft-story buildings that would be affected by the legislation.  

Also, I'm a bit puzzled by how soft-story buildings are defined especially when it comes to smaller buildings (2-4 units). Does "soft-story" mainly pertain to larger buildings? I see plenty of duplexes and triplexes where the living space is on top of the garage. There are also split-level type buildings where part but not all of the living space sits on top of the garage. Would you consider these to be soft-story and more prone to failure during quakes?  How have these smaller buildings performed during earthquakes in recent memory? 

[Manolo D.]

Soft-story buildings are usually the buildings where the columns or foundations are too far from one another.  The city is taking action for "lateral" earthquakes, an example for this is on concrete basements, these doesn't apply, because there are shear walls below the building to hold its weight. If the first floor is too weak to hold the second and other floors, on ##.# magnitude earthquake, then it is not safe, and this is how they identify as soft-story.  A great example for a soft-story is on a 3 story 10-unit apartment, the first floor only contains only 1 column per unit, open all way concrete garage, then in front of the cars is only a stairway to the second floor, second floor and maybe third contains the living spaces. 

Most designs before 1970's don't have enough seismic load factor, so they are weaker than today's standard.  On educated guess, they did not inspect each and every building and built a list, they might pull the data on certain types of buildings, but the list might not be released to the public.

This is good news for me as I do foundation work, too bad for owners who need to spend money to do it, I'm sure there will be a program from the city/state that will help aid the expenses again.