# What does it mean for a building in California to be 'on rollers'?December 22, 2003 12:08 PM   Subscribe

What does it mean for a building in California to be 'on rollers'? Several posters here mention that they are in a building on rollers, but Google doesn't seem to turn up much immediate information on how they work or how they are constructed.
posted by anastasiav to Technology (6 answers total)

Google turns up a ton of information if you know that "rollers" are the flexible bits of a foundation used for a technique called "seismic isolation."

Generally they are big rubber chunks, sometimes with springs, upon which a building is sited to allow for some flexibility with earth movement. The flexibility absorbs some of the energy of the earthquake rather than transferring it directly into the structure and potentially damaging it.
posted by majick at 12:24 PM on December 22, 2003

How Stuff Works has a brief note. I also found some nice diagrams here. But for all I know these cal-ee-forn-ya folks might be talking about something entirely different.
posted by Galvatron at 12:43 PM on December 22, 2003

It probably helps to understand that the motion of an earthquake is frequently side-to-side. Imagine grabbing the end of a table and jerking it two inches across the floor. A marble on the table will probably stay in much the same absolute position. A cereal box might fall right over.

Now imagine that horizontal jerk going back and forth, back and forth for over a minute. At the end of the minute, your marble is pretty much in the same place, having rolled with the shear. Meanwhile your Cheerios are everywhere.
posted by scarabic at 12:49 PM on December 22, 2003

anastasiav, ask the question in the thread itself, I'm sure you'd get answers from the people that mentioned them.
posted by mathowie at 12:54 PM on December 22, 2003

mathowie, its interesting that you say that -- I actually had the post all typed and previewed and everything, and then thought ... no, wait ... I can ask.metafilter! (cue the trumpets).

Actually, once I was cued into 'seismic isolation', it all became much clearer. Thanks for all the answers.

Metafilter: your Cheerios are everywhere ???
posted by anastasiav at 1:02 PM on December 22, 2003

Here's a slightly more technical explanation of base isolation. Most buildings do not have it due to costs. The buildings that are most likely to have it in the US are either:

1) Historic buildings that we'd like to preserve but that otherwise would be unable to withstand the deformations and forces associated with severe earthquakes, even with current structural retrofitting techniques.

2) Critical and essential facilities that must remain operational or largely undamamged after a natural disaster. Think hospitals, fire stations, disaster headquaters etc.
posted by pitchblende at 8:39 PM on December 22, 2003

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