Last month marked the centennial of one of the most widely known disasters in the world: the 1906 San Francisco Earthquake. Now, as people worry about a repeat rupture, researchers are trying to design buildings that will essentially be earthquake-proof.

April 18 marked the centennial of the massive quake that shook San Francisco in 1906, when almost 300 miles of the San Andreas Fault ruptured shortly after 5 a.m., affecting portions of 19 counties. Now many people are asking how a repeat rupture might affect the Bay Area today.

A recent report entitled “When the Big One Strikes Again,” commissioned by the 100th Anniversary 1906 San Francisco Earthquake Conference and prepared by private engineering consultant Charles Kircher, found that if the 1906 earthquake were to happen today, it would affect many of Northern California’s nearly 10 million residents and cost between $90 and $120 billion to repair or replace the more than 90,000 damaged buildings and their contents. As many as 10,000 commercial buildings would sustain major structural damage, and depending upon whether the earthquake occurs during the day or night, building collapses would cause 800 to 3,400 deaths.

The collapse or extensive damage to certain buildings will be the greatest cause of life and economic losses in future earthquakes.

Yet while the vast skyscrapers downtown now may be built to withstand huge pressures, newly constructed buildings in the not-too-distant future may be able to withstand earthquakes of the magnitude that demolished San Fran one century ago.

Working with super-strong materials that can bend, stretch and compress without breaking, engineers say they are working toward the day when buildings will be able to survive earthquakes with little or no structural damage. This according to scientists at Lehigh University, home of one of the largest structural testing facilities in the United States.

Scientists at Lehigh University have tested a next-generation “self-centering” system that uses gigantic steel bands to hold building columns and beams in place during an earthquake.

In allowing the beams and columns to separate, rock and twist independently of one another, the rope-like steel bands — encased in plastic — are meant to prevent a building frame from buckling during an earthquake. The system also uses friction plates that help dissipate the quake’s energy. After the tremors subside, the steel bands pull the beams and columns back to their original positions.

Civil engineer James Ricles, of Lehigh’s Center for Advanced Technology for Large Structural Systems (Atlss) center, said the self-centering system could be ready for commercial use in 10 to 15 years.

But already the system has shown promise.

Said a recent Associated Press article of the system’s testing:

In a hangar-sized lab just south of Bethlehem, PA, gigantic hydraulic pistons subjected a building frame to about 50 percent more force than was generated by the 1906 San Francisco quake. Aside from some popped bolts — which engineers designed to have happen — the frame emerged unscathed.

Despite being 3,000 miles from earthquake-prone California, Lehigh is part of a consortium of 15 universities that participate in the National Science Foundation’s Network for Earthquake Engineering Simulation, a program launched in 2004 to foster research into building materials, designs and techniques that can mitigate earthquake damage, AP noted. For nearly 20 years, the Atlss center has been replicating the great San Francisco quake and its effects on modern building technology by using life-size models or components of actual buildings, said Sause during a recent television interview.

The economical “self-centering” system requires use of already-existing materials — but putting them together in an innovative fashion, Ricles said last month. In the end, it allows you to minimize damage.

“We think the kind of technology that we’re developing now will allow at least modern buildings to survive (a strong earthquake) without significant damage,” said Richard Sause, who is Ricles’ colleague and director of the Large Structural Systems center.

Sause further noted how for most of the 20th century, preventing structural damage during earthquakes was secondary to minimizing loss of life.

But based on the estimates presented in the “When the Big One Strikes Again” report — specifically, that certain buildings’ collapse or damage will cause the most casualties in future earthquakes — well, structural damage and loss of life go hand in hand.

“We’ll always feel the earthquakes,” said Sause. “We’ll always feel the buildings shake and vibrate. But our goal is to keep the building fully functioning after the earthquake so that we’ve effectively avoided the earthquake, if you will, in terms of damage.”

Now researchers are trying to design buildings that will essentially be earthquake-proof.

References

When the Big One Strikes Again
by Charles Kircher
100th Anniversary 1906 San Francisco Earthquake Conference, 2006

Engineers Work on Quake-Proof Buildings
by Michael Rubinkam
The Associated Press, April 18, 2006

Earthquake Proof Buildings
WFMZ News, ch. 69
Story posted on April 18, 2006

Additional Reading:

CNET Special Coverage: Seismic Science
CNET, April 14-18, 2006