Engineers Put Wood House to the Quake Test A team of engineers has built inside a lab a house that mimics the style of those found in quake-prone California: wood frame with a stucco exterior. The University of Buffalo team wants to see if they can improve the durability of houses in quake zones.
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Engineers Put Wood House to the Quake Test

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Engineers Put Wood House to the Quake Test

Engineers Put Wood House to the Quake Test

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RENEE MONTAGNE, host:

In Buffalo, New York today, a team of engineers is sorting through the debris inside of a two-story frame house that was struck by an earthquake. That was the only house in Buffalo hit by the quake. That's because the engineers built the house on top of a pair of shake tables that simulated the real thing. The house was built to mimic the style of homes here in quake-prone California -wood frame with a stucco exterior. Engineers want to see if they can improve the durability of houses in quake zones.

NPR's Christopher Joyce has followed the experiment from construction to the grand finale.

(Soundbite of hammer beating)

CHRISTOPHER JOYCE: Six months ago, a construction crew got a very strange assignment: build a two-story house inside what looks like an airplane hangar on the campus of the University of Buffalo. They built it on top of two metal platforms - hydraulically-driven shake tables designed to simulate big earthquakes. They built it just the way they would have in some Southern California subdivision, but under the watchful eye of university engineer Andre Filiatrault.

Professor ANDRE FILIATRAULT (Engineering, University of Buffalo): It's the first time in this country we truly are going to be testing under three-dimensional ground motion a full-scale wood frame building.

JOYCE: Most earthquake engineering had focused on big steel or concrete buildings. Wood-framed buildings had not really been put to the test much. That changed in 1994, when the Northridge Quake hit California.

Prof. FILIATRAULT: That was a very big eye opener, because for the first time we had a significant seismic event in a highly-populated areas, and wood didn't do that great, certainly from a property loss point of view.

JOYCE: The test house was built on a slab. It's bolted down, and there's no basement. It has a two-story atrium on one room and a garage, complete with an old car inside. In recent weeks, engineers did a few delicate shaking tests.

(Soundbite of machine noise)

JOYCE: On the day before the final test, Filiatrault paces around the building like an expectant father. The stucco job looks a bit slapdashed, but it's not just for show. Stucco is like a mortar jacket around the house. The engineers want to see how the flexing wood frame behaves inside the jacket. It looks pretty normal from the outside, although there are electronic instruments stuck to the exterior walls.

Prof. FILIATRAULT: What you're pointing at, particularly here, is called an accelerometer. And this is an instrument that measures the rate of movement of a particular point in the building. We have over 250 sensors inside and outside the building.

JOYCE: Inside, the team has recreated a fully-furnished home, although the furniture appears to have been salvaged from a campus fraternity.

Prof. FILIATRAULT: We have a living room, a couch. We have a bookshelf. We have lamps. We have real glasses in the windows. We've got a complete dining room here with plates and silverware on a table. We're going to have liquids in the glass and so on, and...

JOYCE: Do you expect these plates and glasses and pitchers to survive?

Prof. FILIATRAULT: It's going to be interesting to see, I think. I think they're going to be having a difficulty, I think, because the level of shaking's going to be pretty high.

JOYCE: In fact, the house will be shaken as if it were just four miles from the epicenter of a 6.7 magnitude quake. As Filiatrault describes it, the shaking will push objects laterally at about 80 percent of the force of gravity, enough to make a 200-pound cabinet slide across a room.

(Soundbite of noise)

JOYCE: Upstairs, there's a child's room that's been California-ized - furniture is screwed to the wall, and the TV is wired in place. Another room, decorated by engineering students, has not been secured. Everything has been photographed and measured - the CDs, the boxes of popcorn and ramen noodles, and the poster of John Belushi - to see where they move.

Filiatrault says big steel and glass buildings are like a skeleton in a quake. The force is distributed along the beams. Wooden buildings transmit energy in unpredictable ways.

Prof. FILIATRAULT: A wood building is different because you have walls. Everything is distributed. So you've got a number of, you know, verticals studs, for example, that takes the load down. And then you have some sheathing, and a zillion number of nails. And then a distributed foundation, all these anchor bolts.

JOYCE: It's this unpredictability that the engineers want to eliminate. Okay. It's shake day, the grand finale. We've got a - audience of engineers in their control room, students and onlookers huddled on a the little balcony about 30 yards away from the house.

Unidentified Man: Please stand by. We're two minutes from test.

JOYCE: This is a test that's been five, six years in the planning. It took seven months to construct the house, wire it up with sensors. And now it all comes down to about 15 seconds of controlled chaos. And they warned us that there are plenty of exits in case something goes wrong.

Unidentified Man: We standby. Test is beginning.

(Soundbite of rumbling)

(Soundbite of applause)

JOYCE: Well, the window boxes fell off but the rest of the house seems to have survived rather well. And the windows stayed intact but it'll take a while before people get inside to see what actually happened.

What actually happened outside was a heavy swaying. The house pitched and bowed but the windows stayed put. Walls cracked in a couple of places, but inside the house was another story. Microphones and cameras inside captured a harrowing scene.

Computer screens and a TV flew across the floor, chairs and bureaus flipped over, the garage door undulated like a sail in a hurricane. It looked like a very hazardous place to be. Afterwards, project engineer John van de Lindt of Colorado State University, watches a video replay of the test. He says he was surprised how well the house performed.

Mr. JOHN VAN DE LINDT (Project Engineer, Colorado State University): Well, I think the power of the earthquake, you know, that you see simulated is amazing. But at the same time, the house did extremely well. I mean we were really - you know, I ought to say I was a little nervous. But, you know, years of work going into something like this. But to see it perform this well - I mean there's structural damage and a lot of non-structural and contents damage, but overall, I think a family that's in a house like that could feel fairly safe.

JOYCE: Engineers will spend two weeks examining the house. Next they plan to build a six-story wooden house and put it to an even tougher test on a shake table in Japan.

Christopher Joyce, NPR News, Buffalo.

MONTAGNE: See the house shake from every point of view at NPR.org.

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