Building An Earthquake Resistant Home
(Inside Science TV) – Earthquakes are unexpected, terrifying and can hit at any time, causing major destruction and even death.
More than 1.3 million earthquakes of varying magnitudes rattle our world each year destroying homes and changing the landscape of cities around the world.
"I saw my city destroyed because of this earthquake," said Eduardo Miranda, a structural engineer at Stanford University in California.
Miranda was in Mexico City when a magnitude 8.1 earthquake hit.
"I've seen firsthand the impact big earthquakes could have," he said. "There were more than 10,000 people killed and hundreds of buildings collapsed."
Miranda and engineer Gregory Deierlein, also at Stanford, have spent decades studying how to make buildings stronger and more resilient against earthquakes and other natural disasters.
"The first thing that's on a structural engineers mind is to keep building safe, to keep them from collapsing. That's number one," said Deierlein.
Now these two have teamed up to build an earthquake resistant house.
"It's going to experience less damage or if it is damaged, it's going to be damaged in a way we can anticipate and repair it quickly," said Deierlein.
"There are two ways to do that. First, we're trying to increase the strength and stiffness of the house," said Miranda.
"So to get all the walls and ceilings engaged through adhesives and other strong connectors to make the house stiffer and stronger than conventional houses," explained Deierlein.
"Then there was another philosophy that we used, which is called base isolation. The idea of base isolation is that, rather than fixing your house to the foundation, what we do is we don't fix it, but rather we build it on special kinds of supports," said Miranda.
They built it on a seismic isolator that separates the house from the vibrating ground. The isolator is made of a piece of thermal plastic – which looks like a hockey puck – that slides over a steel plate.
Miranda explained that the house had 12 of these sliders.
The true test, building the house on a shake table that simulates the strongest earthquakes ever recorded, moving the house 50 inches in just one second.
"Some of these ground motions had accelerations of more than 1G … that's very large levels of ground motions this house is subjected to," said Miranda.
"The walls remained un-cracked, the windows, un-cracked. There was essentially no damage to the structure," said Deierlein.
What will the cost for this new technology be when it becomes available? Deierlein estimates that the enhancements would add an extra 10 to 15 thousand dollars when building a new home.
"We like to think of the house as earthquake resistant, not earth quake proof because even on the isolators there are motions that get into the house. We prevent damage to the walls, damage from cracking, but there will still be shaking in the house things can fall off tables, you would have to brace bookcases," Deierlein said.