San Diego Building Shaker To Test Guts Of Structure
Monday, October 17, 2011
Aired 10/21/11 on KPBS News.
The skeleton of the structure reaches five stories above the shaking table. Square concrete columns wrap around reinforced steel bars. U.C. San Diego graduate student Michelle Chen surveys the tower from underneath her green hard hat.
SAN DIEGO The skeleton of the structure reaches five stories above the shaking table. Square concrete columns wrap around reinforced steel bars. U.C. San Diego graduate student Michelle Chen surveys the tower from underneath her green hard hat.
"Everything is full-sized. It's the same sized columns you would see in a normal sized building. It's basically the core of a whole structure," said Chen.
Life-sized, except for the floor plan. After all, the building is sitting on top of an earthquake simulator, and there are some other differences.
"As you can see, the first two levels, they look pretty much the same," said Chen. "And then the third level up there, which is what we call the fourth floor. There's some strands sticking out."
The columns, floors and ceilings are all wired so researchers can measure how the structure will react to earthquakes.
"All the rebar in the beams have little gauges on them that have the wires connecting out and we're measuring the deformation inside of the beams," said Chen.
But it's not the beams, columns or floors that are the main focus of the project: It is the rest of the building that researchers are interested in, like office walls and ceiling panels.
Lead researcher Tara Hutchinson stands underneath the huge metal platform that the building is sitting on. It's here that huge pistons will actually simulate a quake.
"We have a pair of actuators on either end, large hydraulic actuators, that can push and pull the system at dynamic rates," said Hutchinson.
The machine can simulate mild earthquakes or strong ones; in this case they'll do both.
Hutchinson says she wants to know how quakes will affect a building's plumbing, wiring and things that are there, but not vital to a building's structural integrity. Builders can put that knowledge to use immediately.
"You have plumbers, electricians, you have a ceiling contractor. You have a wall contractor - an interior wall contractor. So each of those trades needs to learn and benefit from a testing program like this," according to Hutchinson.
Seventy percent of the cost of a building is tied up in non-structural components: building those things so they don't fail when they're under stress can save a lot of money after a big quake hits.
UCSD graduate student Elide Pantoli points to two flat walls that rise up the side of the building.
"The two walls that you can see here are the walls of the elevator," said Pantoli. "As you can see in a normal building with a normal elevator, you have two walls. And then on two sides -- they are open because they are the doors of the elevator, right?"
Pantoli said having an elevator that works after a major incident can be a lifesaver, particularly at a hospital.
"After a major earthquake, you want your hospital to be functional. You want it to work. It is not that it is not collapsed. You really want it to work perfectly - 100 percent. So this is what we're trying to achieve, to see if it's working after the earthquake," said Pantoli.
UCSD Jacobs School of Engineering Englekirk Center
Engineers are also building a full-sized staircase that will go up all five floors. Once they begin shaking the building, they'll study where the damage is both visually and with the help of hundreds of sensors.
"You can look physically at what happened during the earthquake. What were the problems," said Pantoli. "But also we will have a lot of sensors and through these sensors we're going to have a lot of data, and we're going to find out really what happened during the earthquake."
Researchers say they'll test the structure with several smaller quakes before they shock the structure with a major shock. That will help them see if there's cumulative damage that might compound a problem during a major earthquake.
Video by Nicholas McVicker.