Earthquake Geek Stuff
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Working in the earthquake business is great fun. Yesterday I got to take a tour of Pasadena City Hall, which is being renovated for earthquake safety. This tour was arranged through the Earthquake Programs Office at Caltech.
We met in the park across the street from City Hall. After signing the release, we walked across and went into the construction site. They are removing the entire original foundation of the building the putting friction pendulum isolators underneath it. The isolators are intended to allow the ground to move something like 24 inches in any direction underneath the building while allowing the building to remain relatively motionless.
They had some of the isolators stacked up in front of the building, so we got a good look at them. Being earthquake geeks, we all had our cameras out to take pictures. After that, we went down into the basement.
In the basement we got a look at the main supporting columns of the building. They are cutting each one off and building a new reinforced concrete mat underneath them. The mat sits on top of the isolators. They also dug a moat around the building, so that when we have an earthquake, the building can rock on the isolators within the moat.
City Hall is a U-shaped building, so they had to dig a big trench so that they could build the moat in a square. That way the two wings of the building will be tied together so that the entire building will move as a unit in an earthquake.
It’s not all that often that I see practical use of the stuff I do at work, so it was an interesting thing to see.
