Japan and the U.S.: Neighbors on the Ring of Fire.
The largest quake in United States history took place not in California, but 1,500 miles to the east, in Missouri. The year was 1811. Professor Gregory Fenves points out that some 30 U.S. states are affected—a fact most Americans tend to forget. But the Pacific Ring of Fire is where most earthquakes take place, and so it is not surprising that for PEER researchers, Japan is right next door. "Our biggest research collaborators are in Japan," Fenves says. "Japan has the largest shake table now, at the E-Defense facility in Miki City just outside Kobe, inaugurated a year and a half ago on the anniversary of the Kobe earthquake. The research director, Dr. Masayoshi Nakashima of Kyoto University is a close friend. I go to Japan once or twice a year, and Japanese researchers often come to Berkeley. The collaboration between our two countries has been ongoing for 25 years." (To see the shake table in action, check out the E-Defense website: www.bosai.go.jp/hyogo) Fenves says that similar circumstances bind both locations. Both Japan and California have major cities residing on earthquake faults. Both have similar types of dense urban construction, with many pre-1975 reinforced concrete buildings that were not designed to deform during an earthquake. "We both have the soft soils that can liquefy in earthquakes, and while we have use different structural systems for our residential wood construction—they have similar vulnerabilities."
The earthquake codes are also similar. "Japan legislates building codes on the Federal level while in the U.S., it's done through municipalities," Fenves says. "Usually, the U.S. building code is a little bit ahead of Japan's, while Japan is a bit ahead of us on bridges. Design philosophies are somewhat different. We make our buildings more flexible to dissipate energy during an earthquake. They make theirs a little bit stiffer and stronger."
Hybrid testing techniques have also brought the two locations together. The "hardware in the loop" of a software simulation can be located anywhere within reach of a data network, even across the Pacific. This November, for example, portions of a bridge will be physically tested at PEER and in Kyoto, with software analysis done at the Tokyo Institute of Technology. That project will lead to a larger one: a very large, full-size shaking table test at the Miki city facility.