S.D. Experts to Study Damage in San Francisco

Three researchers who study earthquakes at UC San Diego’s unique earthquake testing laboratory flew to San Francisco early Wednesday to help determine why some bridges, roadways and buildings collapsed during the temblor.

The three scientists, who were unavailable for comment, use a $2-million earthquake testing center at UCSD’s La Jolla campus to construct full-scale models of structures that are subsequently destroyed by earthquake-like forces. Those continuing studies will be used to improve design and construction methods, thereby reducing earthquake casualties and property damage.

The California Department of Transportation has contracted with the center to help make older bridge supports less vulnerable to earthquake damage. That research “might be highly relevant to what happened in the Bay Area with the Nimitz freeway,” according to Lea M. Rudee, dean of UCSD’s School of Engineering.

Could Be Highly Relevant

“Many of our bridges and freeways, and maybe the one that caused all the damage (in Oakland) were built with the older kinds of supports,” Rudee said. “If that Nimitz freeway is an older one, (UCSD’s) research could be highly relevant.”

Although the UCSD researchers may study the Nimitz freeway collapse that killed scores of people, they will also study bridge supports that show no obvious signs of damage, Rudee said.

“While the Nimitz freeway has received most of the headlines, (Caltrans) does know that it failed,” Rudee said. “The other issue of perhaps even greater importance is helping to determine the extent of damage done to (bridges) that are only slightly damaged.”

Caltrans has awarded the UC facility a $717,000 contract to “physically test what we call shell details, the steel blankets that would wrap columns” and increase their strength, according to Caltrans spokesman Jim Drago. UCSD’s researchers now are testing a brace that they believe will increase the likelihood that state-maintained bridges will survive earthquakes.

Caltrans also has awarded UCSD a $135,000 contract to “assess what happened to the I-5/I-605 interchange during the 1987 quake,” Drago said. “That multicolumn span suffered serious damage,” he said of the Los Angeles County intersection.

UCSD’s earthquake laboratory “is the place we go to do this kind of research,” Drago said.

Statewide, Caltrans believes 700 of the 13,000 bridges it is responsible for need to be reinforced. It would cost about $65 million to repair those bridges, Drago said.

Since 1985, a UCSD research team that includes Gilbert A. Hegemier, Frieder Seibleand Nigel Priestley have used the laboratory and complicated computer models to help determine if older bridge supports and road surfaces can be repaired or replaced to improve their resistence to earthquake damage.

“The unique feature of our lab is that it’s the largest of its kind in the country,” Rudee said. The laboratory uses a complex hydraulic system to subject full-scale structures to earthquake-like forces. The hydraulic system slowly and deliberately destroys buildings and bridge supports that can be as tall as 5-story buildings.

Before the 1985 opening of the UCSD facility, the only full-scale testing laboratory was at a national science center in Japan, where a joint U.S.-Japanese earthquake research program existed.

Existing Testing Methods

Scientists are using the UCSD center to study a 60-foot slab of concrete that was cut from an aging freeway near Fresno. Caltrans’ engineers, using existing testing methods, determined that the roadway was nearing failure. UCSD researchers, who used their hydraulic system to slowly destroy the highway stretch, determined that Caltrans’ testing techniques were accurate, and that the bridge needed to be replaced.

They have also constructed models of bridge supports that have been upgraded to better withstand the forces unleashed by an earthquake.

Although the lab and computer models give insights into how and why roads and bridges fail, researchers often travel to cities such as San Francisco and Mexico City, where they can get first-hand information about structures that survive or are destroyed by quakes.

“I’m sure we’re going to add major new information to our understanding of how buildings and structures respond to an earthquake,” Rudee said. “And that knowledge could affect future building codes.”

Earthquake researchers will uncover a wealth of data in San Francisco because some of the city’s buildings, roads and bridges date from the 19th Century. “They’re particularly interested in San Francisco, because all of these structures were built exactly according to code,” Rudee said.