Balancing Barrels

Imagine a lot of large barrels full of liquid, in racks, during an earthquake. You wouldn't necessarily want to be around, just in case those racks weakened or broke or the barrels rolled right off them. Unfortunately many California winegrowers are perched close to active earthquake fault zones and this is precisely the scenario they want to prevent.

The challenge To protect wine barrels stored in California's earthquake-prone wine regions, you first need to understand how racked barrels behave during a quake.
The challenge To protect wine barrels stored in California's earthquake-prone wine regions, you first need to understand how racked barrels behave during a quake.

To compensate for the kinds of dynamic forces experienced by the racked barrels during a quake (to protect your valuable wine), you need to understand what's happening, so California Polytechnic's Civil Engineering team simulated the situation. They placed barrels filled with water onto a giant steel table and tied everything down with braided steel wire. Then they mounted a series of SpaceAge Control's position transducers from the table to the barrel's center of mass to measure rocking-sliding behavior, added lateral transducers on the frame to measure how much uplift each barrel experienced on each end, and placed two more transducers on the table to see how much relative sliding and rocking behavior the table was experiencing. Each barrel also contained an accelerometer to measure acceleration data. The results? The culprit for most winery-related earthquake damage is barrel slide, and the experiments showed this phenomenon was most pronounced for lower frequency ground motion pulses (2 Hz). System damping from 1%–7% didn't help although increasing the coefficient of friction led to greater displacement but with less force transmission between barrel and racks (slide).

Contact Joyce Anderson, SpaceAge Control, Inc., Palmdale, CA; 661-273-3000, x-201, [email protected], www.spaceagecontrol.com; Jeremy Stanley, California Polytechnic State University San Luis Obispo, Dept. of Civil and Environmental Engineering, San Luis Obispo, CA; 805-234-3359, [email protected].

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