October 2006 Issue of Wines & Vines

Cal Poly Devises Quake-Resistant Barrel Rack

by Kathy Marcks Hardesty
Quake-Resistant Barrel Rack
The otherwise standard rack of eight wine barrels was fitted with the new seismic-resistant equipment developed by Cal Poly researchers, and withstood an earthquake simulation atop the "shake table" without mishap.
In the same evening (Aug. 2) that a 4.5 magnitude earthquake rattled wineries in Sonoma County, a professor at Cal Poly in San Luis Obispo staged a dramatic demonstration of a new barrel stacking technology designed to minimize winery damages during quakes.

Wine cellars in San Luis Obispo County suffered substantial seismic damage from the 6.5 San Simeon earthquake on Dec. 22, 2003, so the small crowd of winemakers, cellar masters and other local winery personnel who attended the demonstration had more than a scientific interest in the new technology on display.

What they saw was the result of three years of work by Cal Poly structural engineering professor Charles Chadwell and his team--a modified barrel stacking rack that uses ball bearings to allow the racks to slide rather than sway (and topple) during a quake.

No one in the wine business has more respect for the forces of faults than the cellar crew at Turley Wine Cellars in Paso Robles, where the San Simeon shaker toppled stacks of 600-pound barrels, which bounced on the cellar floor like rubber balls. Unlike rubber balls, however, some burst. Bungs exploded out of others. It resulted in the loss of 4,000 gallons of Turley's 2002 and 2003 vintages when the temblor hit Paso wine country.

In fact, just two days before the San Simeon quake, Chadwell had submitted a grant proposal that would allow him and his students to research how better to safeguard wine storage during seismic activity. Soon after, he received a $40,000 grant from Cal Poly, which he used to supply the Advanced Technology Laboratories with a wine barrel lab, a full-scale hydraulic powered "shake table" and computer equipment that can recreate the sliding, rocking and shifting motion of quakes like San Simeon or the 1994 Northridge quake in Southern California.

Immediately after the San Simeon shake, Chadwell and engineering students visited Paso Robles wineries, including Turley, Justin and Wild Horse, that experienced heavy damages from the quake.

"We spent nearly two years of analytical study, starting with computer models," Chadwell recalled. The team devised a mathematical formula to estimate earthquake loss for any winery. By determining soil type where the winery was built, the distance to the nearest earthquake fault and the maximum size quake it can produce, they attempted to discover the solution to stacking barrels. "After nearly two years of research, two months ago I woke up and figured it out. Two weeks later we were ready to promote it."

On Aug. 2, Chadwell unveiled his invention, a steel barrel rack with stainless steel ball bearings that allow it to slide gently back and forth. He began his presentation with a video demonstrating the disastrous effects of a simulation of L.A.'s Northridge quake on a standard stack of eight barrels, vertically positioned. Chadwell then turned on the shake table to demonstrate just how well his new technology performs at preventing the same type of stack from toppling. Despite safety tethers to protect onlookers, winemakers who came to learn from the demonstration stood back a respectful distance.

This time the eight-barrel stack didn't teeter. The only visible movement was its forward and backward sliding on the shake table, as steady as a professional skater on ice. Chadwell's discovery can potentially save wineries millions of dollars if an earthquake happens. Topco Inc. of Grover Beach (south of San Luis Obispo) donated the portable steel wine racks and is a partner in the project. Robert Mondavi Winery donated the barrels.

Chadwell estimates the improvements will only cost about $30 more than a normal rack that sells for $65. Wineries will also have the option of buying a "seismic tray" that snaps into an existing rack. Ending on a positive note, Chadwell added, "Because of the codes for building design, wineries only have a 10% chance of sustaining damage in a 50-year time period."
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