Japanese Structure Withstands Earthquake Test
ROBERT SIEGEL, host:
In Japan today, in a huge warehouse, engineers watched in anticipation as a countdown began.
(Soundbite of machinery)
Unidentified Man: (Foreign language spoken)
SIEGEL: A six-story wooden model condominium was shaken by the equivalent of an earthquake. Had that quake been real, it would have been a magnitude 7.5 quake. It was a test, and it was said to be the largest simulated earthquake ever attempted with a wooden structure.
John Van de Lindt of Colorado State University is the project director. And he now joins me from the Japanese city of Miki.
And first of all, how did that six-story wooden structure fare in the artificial quake?
Professor JOHN VAN DE LINDT (Civil Engineering, Colorado State University; Project Director, NEESWood Capstone Test): Well, it fared actually very, very well. We were expecting to see a little bit more damage. And in fact, when we entered the building after the earthquake, we saw just hairline cracks and it performed excellently.
SIEGEL: I want you to describe the setup. The condo, the six-story structure, was built on, what I gather, amounts to a huge table that shakes.
Prof. VAN DE LINDT: That's right. It's a steel cube that has a payload capacity that's about two and half million pounds. Our building was approaching about one million pound. The table is about (unintelligible) I think it's about 50 by 65 feet.
SIEGEL: And what were you trying to determine?
Prof. VAN DE LINDT: We were trying to do two things. We were trying to determine how these types of buildings behave so that we can model them better; and then also to validate a new design approach.
SIEGEL: A new design approach.
Prof. VAN DE LINDT: That's correct. It's something known as performance-based seismic design. We have all the components, say, you know, a hundred, 200 components in a building. And if we design each one to basically withstand a certain level of earthquake, then we put them all together, it doesn't necessarily mean that the system as a whole is going to respond that same way.
In performance-based seismic design, we treat it at a system approach. And so we design explicitly to get that performance at the system level.
SIEGEL: You're testing the whole, not just the sum of the parts here in terms of…
Prof. VAN DE LINDT: That's right. And we're designing for the whole.
SIEGEL: So, what did you learn from today's test?
Prof. VAN DE LINDT: Well, we learned a couple of things. I'd say the major thing that we learned is that the design approach we developed in the course of our project over the last four years, we validated that. We learned that that does work. And then we learned the light frame wood structures can be designed for a major, major earthquake and perform very well. I mean, we had almost no damage, which is just astounding.
SIEGEL: So, tell me what's going through your mind as you're about to see a six-story wooden structure that's been built for the test, it's on the big shake table in Japan. And for all you know at that moment, if things haven't been calculated properly, you could be looking at a huge woodpile in a few minutes. What's going through your head at that time?
Prof. VAN DE LINDT: Well, that's actually a very good question because I think what goes through my mind right before the test, when you hear the countdown -of course, it's in Japanese, but you hear that countdown: 10, nine, eight, all the way down, then I start to hear the shake table. I can see the shake table move.
The first thing that goes to mind is I look at the base. I look at the roof. And I know the earthquake record so well. I know if, you know, if it was going to fail, I know when it would fail. So, there's definitely some nerves that, you know, I don't know if I hold my breath or not, I can't remember, but…
(Soundbite of laughter)
SIEGEL: Well, Professor Van De Lindt, thank you very much for talking with us about it. Good luck.
Prof. VAN DE LINDT: Okay. Thank you very much.
SIEGEL: That's John Van De Lindt of Colorado State University, but he spoke to us from Miki, Japan, where his group just tested a six-story wooden structure on a shake table. It was a simulated earthquake.
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