EARTHQUAKE / LIFELINES OF L.A. : ALTERNATIVES : Building on Experience : After a deadly quake in 1923, Japan committed itself to strengthening its roads, including spending huge sums on research. The country's engineering philosophy differs from U.S. approach.

By RICHARD LEE COLVIN

Feb. 16, 1994 12 AM PT

TIMES STAFF WRITER

Each time an earthquake’s brutal force exposes the relative fragility of California’s freeways, momentum builds for strengthening bridges and rethinking designs for the future. In Japan, it took only one such seismic call to action, the 8.3-magnitude Kanto quake of Sept. 1, 1923, that killed more than 140,000 people around Tokyo.

“Because the Japanese remember” that quake, said Caltech engineering professor emeritus George W. Housner, “their freeways are stronger and heavier” than roadways here.

The country’s reaction to the 1923 disaster resulted in a fierce commitment to limiting the death toll from subsequent killer quakes, including spending huge sums on earthquake engineering research. In Japan, an area 10 times as seismically active as California, where three vast plates of the Earth’s crust grind against and beneath one another, a quake of 8.0 magnitude or higher is considered an imminent threat.

And if it comes, the Japanese want their rapidly expanding 4,000-mile expressway system to be ready.

“They have a willingness to recognize the potential problems and to face up to the fact that it is going to take major dollars,” said Reidar Bjorhovde, a professor of civil engineering at the University of Pittsburgh who spent six weeks recently studying Japanese construction techniques. “I think we have to be willing to do that as well.”

Californians who have driven from Los Angeles to Oregon on the usually wide-open Interstate 5 would find Japanese highways frustrating in many ways. All Japanese highways are toll roads, and a trip of that length would cost $50 or more. Moreover, all but the newest expressways in Japan are only two lanes in each direction and often congested.

Although Japanese highways are usually elevated, to preserve precious real estate for other uses, soaring high-speed overpasses such as the collapsed Golden State-Antelope Valley interchange do not exist. As a result, connecting turns are sharper and slower.

In other ways, quake-shaken Californians might find driving long distances in Japan comforting. To make taller structures more stable, supporting columns are usually connected with crossbeams to help them resist an earthquake’s sideways forces. Other strengthening techniques include using more steel girders in spans, designing a wider overlap of adjacent spans and making columns or piers as much as 50% more massive, with more reinforcing steel.

Kasuhiko Kawashima, an engineer who is head of earthquake engineering for Japan’s Earthquake Disaster Prevention Department, said that after the 1923 quake, the Japanese began trying to calculate the sideways force that structures would have to withstand.

“Because of our many earthquake experiences since then we have gradually improved our earthquake design methods,” he said.

The 1964 Nigata quake and the 1971 Sylmar earthquake each resulted in stronger designs. Since then, the Japanese have concentrated on designs to combat soil liquefaction and on strengthening the connections between columns and spans.

Kawashima said Japanese bridges have to be stronger than California’s because earthquakes there are more frequent and potentially far more intense. In addition, a lack of land often requires bridges to be built on poor or wet soils where liquefaction is likely.

Japanese construction standards require concrete to come through quakes virtually undamaged, whereas American designers expect some crumbling or breaking. “Even if a very, very big earthquake were to occur, we cannot allow the concrete to fail,” said Hiroshi Mutsuyoshi, an associate professor of construction engineering at Saitama University.

The effect of all those techniques is to make the supports for elevated freeway bridges in Japan far stiffer, although researchers are trying to develop ways to counteract that. The fear is that stiff structures are brittle and could collapse in a cataclysm if bent too far by a massive earthquake.

“My personal opinion is that they have a lot of vulnerability in their bridge structures that is going to show up in a big earthquake,” said James H. Gates, Caltrans’ chief of earthquake engineering in the division of structures.

Bridges in California, he said, are designed to bend by building flexibility into joints and the connections between columns and spans. Joints connecting sections of the San Mateo Bridge over San Francisco Bay are designed to be displaced by an earthquake by as much as five feet without coming apart.

But many Japanese designers believe that those flexible elements create weaknesses, which have been demonstrated in each of the state’s major earthquakes since 1971.

The California Department of Transportation’s top bridge engineers and designers believe that retrofitting older structures and the designs of newer structures are solving those problems. Even so, the design goal for California’s bridge engineers is quite different from that of the Japanese.

The Japanese “tend to design everything for the worst case,” said James E. Roberts, Caltrans’ chief bridge engineer. “But we’re trying to design rationally based on the probability and the statistical possibility of that happening.”

In California the risk is that “in the real biggie, (a bridge) might yield enough that you would get some permanent damage,” Roberts said. “But you repair that.”

The weightier Japanese highway designs are 10% to 20% more expensive than U.S. techniques, depending on the type of structure, experts estimate. Part of those costs are borne indirectly by the government in the form of subsidies to the Japanese steel and concrete industries. In Japan, highways are paid for mostly with tolls.

“If you get more rigid and more expensive structures, then the further you get in time from a major earthquake, the more the public is going to say, ‘Hey, what are you wasting money for?’ ” said Roland Sharpe, a Cupertino structural engineer who has advised Caltrans on seismic issues and who is the only non-Japanese honorary member of the Japan Structural Consultants Assn. “Now we’re very close to an earthquake, and people are saying, ‘Why didn’t you do more?’ ”

Sharpe said that in general, California highway bridges of comparative age are as safe as those in Japan. But more of the overpasses there are newer and use more up-to-date designs, he said.

Still, earthquakes have damaged more than 3,000 highway bridges in Japan over 70 years, although none have collapsed.

As in California, the collapse of overpasses in the 1971 Sylmar quake caused the Japanese to reanalyze the seismic safety of their bridges. More than a quarter of 40,000 bridges that were inspected were found to need some type of retrofitting, according to a paper presented last month in Berkeley by Kawashima, the earthquake engineering expert.

Retrofitting in Japan tends to be a much more comprehensive undertaking than here. Methods include sinking more piles into the ground, enlarging the footing or base of columns, adding reinforced concrete around columns or adding cross beams for lateral strength.

Despite the differences in perspective, California bridge designers admire much about the Japanese system for researching new technologies and designs. The Japanese established the world’s first earthquake engineering research institute at Tokyo University soon after the devastating 1923 quake. Government, universities and private companies cooperate on the development, testing and marketing of technological advancements.

The Japanese also pump far more money into earthquake engineering research, partly because of a requirement that engineering and construction companies spend as much as 1% of their income on it. That money goes for hiring hundreds of engineers to consider earthquake issues and for research equipment, such as huge shaking tables that can reproduce an earthquake’s forces on built-to-scale structures.

One such shaking table, maintained by the government’s Nuclear Power Engineering Corp. at Tsukuba Science City northeast of Tokyo, is 50 feet by 50 feet and is capable of testing 1,000-ton test structures. That device cost hundreds of millions of dollars to build and costs $1 million a month to operate, according to Housner, who chaired a committee appointed by then-Gov. George Deukmejian that made recommendations to Caltrans after the 1989 Loma Prieta quake.

“They’re just way ahead of us in the number of people (involved in earthquake engineering) and the experimental facilities,” Housner said.

For example, the government gives a boost to private construction companies working on methods of controlling the response of large structures to high winds or earthquakes by means of energy-absorbing springs or other devices.

“The governmental labs offer themselves for testing, providing equipment, staff and materials that will aid the companies in perfecting the new products,” Bjorhovde of the University of Pittsburgh said. “That is a model. . . . and I would like to see that sort of thing evolve here.”

Other engineers said Japanese researchers are also getting attention for their work in analyzing the effect of soft or wet soils on freeway structures and in what is known as base isolation. Base isolated structures are built on rubber or steel bearings that allow them to remain stable during an earthquake.

Recognizing that both countries have much to learn from each other, engineers, scientists and policy-makers from Japan and the United States have been meeting annually for at least 15 years to discuss advances in earthquake engineering.

But Gates, the Caltrans earthquake expert, believes that California could learn more if state engineers were allowed greater freedom to travel--both to the sites of distant, destructive earthquakes and to participate in more joint research activities with the Japanese and scientists in other countries, such as Italy and New Zealand, where new research is being conducted.

Gates and other engineers have traveled to Japan to learn from their research. But, he said, they usually have to apply for federal grants to pay their way.

“One of the big sore points is that we were told that we had to improve our technology, yet we continually get slammed on budget requests for out-of-state travel,” he said.

California versus Japan

Japanese highways are squatter, more massive, somehow more grounded than those in Southern California. Japanese designs generally require more steel, in columns and spans, and more and higher quality concrete. Engineers debate whether highways designed that way will be flexible enough to move to the forced rhythm of an earthquake. But there is no doubt that the additional material adds to construction costs.

CALIFORNIA FREEWAY

Roadbeds: Overpasses are essentially hollow boxes made of self-reinforced concrete.

Columns: Generally are built taller and narrower in California.

Interior support: Vertical rebar wrapped by circular steel provides strength within poured concrete.

JAPANESE EXPRESSWAY

Roadbeds: The reinforced roadbeds of most overpasses contain more steel and more concrete than in the U.S. Some overpasses are as much as 80% steel by volume. The Japanese also build more all-steel overpasses.

Columns: Japanese support columns are as much as 50% wider.

Cross beams: Used to stabilize the few tall overpasses. Generally, however, Japanese roadways are built lower to the ground and interchanges are less sweeping, which slows traffic.

Footings: Bases are enlarged and piling is driven deeper.

Adding Support: Because many Japanese expressways are built in areas of soft soil, on artificial fill such as along Tokyo Bay, or on the sediment of riverbeds, the Japanese have developed techniques for keeping structures stable. These include making the structures more rigid, sinking piles deep into the ground and adding to the bulk of column footings.

COMPARING THE DIFFERENCES

FREEWAY MILES Los Angeles County: 528 Japan: 3,975

HOW FINANCED Los Angeles County: Use taxes, including 14 cents a gallon federal gas tax and 18 cents a gallon state gas tax Japan: Use taxes, steep tolls for most expressways

COST (per mile) Los Angeles County: $3 million mile (non-urban) Japan: $2.6 million to $6.6 million (non-urban)

NEWEST FREEWAY Los Angeles County: Century Freeway. 17 miles, Norwalk to El Segundo. Opened 1993. Japan: Gai-kan Expressway. About 53 miles (20 miles open), Outer Ring route, Tokyo. Opened 1992 (partial)

SPECIAL FEATURES Los Angeles County: Six lanes, two carpool lanes, closed circuit TV monitoring cameras Japan: Six lanes, sound walls, extensive landscaping

Source: Caltrans. Hiroshi Mutsuyoshi, associate professor of construction engineering, Saitama University, Saitama. Japanese consulate; Researched by RICHARD LEE COLVIN / Los Angeles Times