Buildings that use base isolation are more likely to survive a strong earthquake and be functional afterward.
Inherent in the American approach to seismic engineering is a risk calculation: Many American engineers operate on the assumption that a building, which might be used for 50 years before it is torn down and replaced with a new one, has a relatively small chance of being hit by a huge earthquake.
“If you spend the money today and the earthquake happens tomorrow, then congratulations, you’ve done a good job,” said Ron Hamburger, an American structural engineer who is perhaps the leading authority on the building code. “But the fact is, truly significant damaging earthquakes will affect a place like San Francisco or Los Angeles maybe once every 100 to 200 years.”1
“How lucky do you feel?” he added.
- 1. Earthquakes are of course natural phenomena. But the amount of damage they cause is a function of decisions made by politicians, engineers and business executives. Japan and the United States, two of the world’s most technologically advanced countries, have the same problem — how to protect people and society from earthquakes — and yet they have responded in very different ways.
Japan, through both government mandates and its engineering culture, builds stronger structures capable of withstanding earthquakes and being used immediately afterward. The United States sets a minimum and less protective standard with the understanding that many buildings will be badly damaged.
The two approaches reflect different attitudes toward risk, the role of government and collective social responsibility. Analogous to America’s debate over health insurance, the American philosophy has been to make more resilient buildings an individual choice, not a government mandate.
“Do we want to be more like Japan and are we willing to pay the price?” said Joyce Fuss, president of the Structural Engineers Association of California. “A lot of people would say ‘no’ and maybe some people would say ‘yes.’”