"In 1976, we were shocked by the strong earthquake that happened in Mainland China -- the TanghShan earthquake," said Tony Hu, professor of civil engineering. "Just one shock, the whole city was destroyed and 250,000 people were killed.
"We decided that we have to do something to make structures safe in order to save people's lives," he said. "And that led to the development of the Stiffness Decoupler for Base Isolation of Structures."
Using isolation technology, Hu and co-inventors Stu Swartz, professor of civil engineering, and Phil Kirmser, professor emeritus of civil engineering, have been able to construct a building that is strong, yet protected from earthquakes because the base of the building sits on a stiffness decoupler system which reduces the transmission of ground motion to the building during earthquakes.
"The shaking table machine consists of a base made of steel girders which rest on wheels running on tracks," said Kirmser. "The base is moved by a hydraulic piston and high pressure oil, and is controlled in a way to make the base move, the way the ground would during an earthquake.
"The building rests on slick, friction-bearing pads, so that when the ground moves the building doesn't move as much," he said. "There is some sliding between the building and the ground, but the sliding reduces the effects of ground motion, so not only is the building damaged much less, the people in it are safe."
The researchers created a building model from concrete blocks and used seismic recordings of past earthquakes to simulate an actual earthquake occurrence. Findings depicted a significant reduction of building movement with their invention.
"Results showed that the peak ground acceleration for a moderate earthquake was reduced three times, and for a strong earthquake, a reduction of 1/5 the peak ground acceleration during a quake," said Hu. "We shook our building over 100 times, and we haven't had any cracks in the structure.
"Usually a building made from concrete blocks is very vulnerable to an earthquake, but ours stands in perfect condition," he said. "You can walk in, sit inside and it is very safe."
The researchers hope that this invention might one day be used in areas where earthquakes are active, such as California, Alaska and nations around the Pacific rim. In addition to being applied to the structural design of buildings, it can also be used for stabilizing bridges, oil tanks, chimneys and power plants.
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Prepared by Robyn Horton.
For more information contact Tony Hu at 785-532-1577, Phil Kirmser at (785) 532-1579 or Stu Swartz at (785) 532-1572.
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