Friday, September 20, 2013

Floppy buildings fine for earthquakes


Everywhere I go, I see floppy buildings going up.  Any condo or office building has virtually no lateral stiffness.  As long as the joints are ductile, it is good to go.  Every new earthquake brings painful lessons, and I expect a lot out of the next one.  In this experiment giant concrete blocks were thrown around.  Could you survive this?

The great rush to floppiness is caused by these shake tables.  You could not put a stiff building here and submit it to a broad frequency range.  That's because the shake table does not allow radiative damping, and they scale the motions by acceleration.  We are all doomed!  :)

So, if you live and work in a floppy building, make sure the tables are sturdy.  Do not run out into the street with your $80 million dollar 30 second warning (California).  Do not hang around the giant stacks of TV's in Costco.  Floppiness rules!

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