Friday, September 09, 2011

#SECURITY: "Simulations Guarantee Earthquake-Proof Stadium"

California Memorial Stadium was slowly being pulled apart by a fault line that runs down its middle, but computer simulations have enabled a face lift that secures fans even if "the big one" hits during a game.
If a seismic fault was discovered to be splitting a sports stadium in half even without a quake, would the smart thing be to relocate the stadium? Not according to California engineers who claim to have validated a $321 million renovation of California Memorial Stadium with detailed computer simulations which "allow the fault to rupture without endangering life," according to David Friedman, a principal with Forell/Elsesser Engineers, which did the structural engineering design.
By putting threatened stands atop moveable seismic blocks that ride out the earthquake, fans in the new 63,000 seat stadium "will find themselves taking a ride--but a safe one."

Even if a quake splits the California Memorial Stadium in half, computer simulations assure fans they will be safe atop modular stands that slide around without coming apart.

California Memorial Stadium straddles an active earthquake fault--the Hayward Fault--which over the stadium’s 88-year life has split the structure in half with up to 9-inch cracks, requiring innovative seismic engineering to repair and renovate.

According to the computer simulations, the renovated stadium will be able to survive tremors without sustaining significant damage. Even if the "big one" hits, fans will ride gigantic seismic blocks that can move up to 6 feet laterally and drop down up to 2 feet without coming apart. The seismic blocks will be floating on a 4-foot thick concrete mat covered with two-layers of high-density plastic with sand in between to facilitate sliding. The computer simulation also shows that by dividing the overhanging boxes for the press and VIPs into five 60-foot wide modules, they will be able to safely sway and spring back on giant shock absorbers that damp movement down to about 1 foot.

Structural engineers and seismic specialists helped construct the detailed computer models whose simulations allowed them to verify the soundness of the design. First trenches were dug and boreholes were drilled all around the stadium and adjacent areas in order to accurately model the exact geological formations of soil and rocks. What the core samples revealed was that over the last 90 years the Hayward Fault has been moving in a geological process called "fault creep." The improved structure, however, will have adjustable gaps between sections so that the fault can continue to creep without cracking.

To see one of their simulations of what will happen during an earthquake, check out the stadium-quake animation.

The renovations currently under way at the stadium are due to be finished in time for the 2012 football season. (The Golden Bears are using the AT&T Park in San Francisco for the 2011 season while construction is underway.)

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