Engineering doctoral student studies the effects of earthquakes on buildings in a KU lab.
Jon Lindsey knows how to make a solid steel beam used in the construction of multi-story buildings act like a hinge.
By so doing, the Ph.D. student in civil engineering at Kansas University hopes he can point the way to better design of buildings in areas prone to earthquakes.
"The potential of this is it allows the beam to do what it would like to do," Lindsey said. "It would like to go plastic. It actually dissipates the energy of the earthquake."
When floor beams dissipate the energy of an earthquake by becoming plastic at certain points, it preserves the upright column steel beams that hold up the walls of the structure, said Lindsey and Kim Roddis, associate professor of civil engineering.
"At least the building is still standing," Lindsey said.
Interest in preserving columns and the joints between them and the floor beams began after the Northridge, Calif., earthquake on Jan. 17, 1994, in which 61 people died and between $13 billion and $20 billion in damage resulted. The Northridge quake was a magnitude 6.8. In contrast, Monday's earthquake in Taiwan has been estimated as a magnitude 7.3 to 7.6.
On the scales used to measure earthquakes, an increase in one number, say from 6.5 to 7.5, means the quake's magnitude is 10 times as great.
In the Northridge quake, welded joints between floor and column beams failed. Welding was the most common method of connecting floor and column beams.
In an earthquake, a building is only as strong as its connections.
"A building is actually several thousand connections that hold in place several thousand beams," Roddis said.
With the $70,000 earthquake simulator he designed and built, Lindsey can test different types of connections between floor and column beams.
In his first series of tests, Lindsey created the hinge effect on a steel beam. The column beam was connected to a floor beam with a series of bolts and reinforced by a plate of steel. On the opposite end of the floor beam was a hydraulic actuator, a sort of piston that moved the end of the floor beam five inches to the right and left.
About a foot away from the connection, the floor beam's sides were bent and crumpled, but the connection did not break, even under 30,000 pounds of stress.
Because the connection was able to react to the stresses of the simulated quake, the energy from it was dissipated in the floor beam.
What Roddis describes as "graceful," slow failure was created in contrast to a catastrophic failure. Given the average short duration of most earthquakes, a building with connections like that would remain standing in this experiment.
The earthquake simulator is a steel beam frame in the shape of a triangle. Each side of the triangle is about 15 feet long.
Most of the cost of the simulator comes from the fabricated steel it took to make.
"Fabricated steel is not cheap," Lindsey said.
Nucor-Yamoto Steel Co. donated the steel and it was fabricated into beams at Haven Steel's Ottawa plant.
Lindsey has been working on the earthquake simulator for six of the 11 years he has been at KU. He approached Roddis about doing work on the simulator while he was a graduate student in architectural engineering. When he completes his dissertation in a year, based on his experiments with the simulator, he hopes other students will use the simulator to do more work in the field of seismic design.
Lindsey plans to become a licensed civil engineer in private practice after earning his doctorate.
-- Erwin Seba's phone message number is 832-7145. His e-mail address is eseba@ljworld.com.
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