Scientists from the National Science Foundation were able to simulate earthquakes for the first time Nov. 15, using powerful hydraulic presses.
The experiment, which was conducted at four laboratories across the country, tested the strength of common building materials such as pipes, and above-ground structures such as bridges and power lines. During the first test run at Cornell University’s $2.1 million earthquake lab, researchers simulated the effects of an earthquake on a 30-foot section of 6-inch polyethylene piping. The plastic pipe, which is the type usually used to carry natural gas, was buried under 12 1/2 tons of sand, and then the hydraulic presses applied 25,000 pounds of pressure to the ends of the pipe. The pipe was off center and buckled quickly.
Similar tests were conducted simultaneously at the University of Illinois at Urbana-Champaign, Oregon State University and the University of California at San Diego. The tests were part of the grand opening of the Network for Earthquake Engineering Simulation, which is sponsored by the NSF. The $81.8 million network is a system of 15 earthquake test laboratories at universities in 10 states.
Vilas Mujumdar, a structural engineer and program director for NEES, said multiple laboratories can study the effects of an earthquake on different parts of the same structure, such as a bridge or a building.
“We can test the components of buildings and bridges, but you never know how the entire structure behaves,” Mujumdar said. “To test the entire system, each part at a different lab is connected through the Internet. Then we can understand how the earthquake impacts entire buildings.”
According to Joy Pauschke, an NSF official who helped plan the first experiment, the idea for NEES emerged during the early 1990s at several NSF workshops. Approval for the project was granted in 1998, and the test laboratories were built during the past five years.
Each laboratory is linked through the Internet to other labs so that researchers can share data as the experiments are conducted.
Because different NEES laboratories have different equipment, the network can test a variety of structures and geomaterials, Pauschke said. Some labs have similar basic equipment such as strong floors and reaction walls, while other labs have equipment including hydraulic actuators, shake tables, geotechnical centrifuges, tsunami wave basins and shakers to shake structures and soils.
Hydraulic actuators push reaction walls, which are 20-foot walls of concrete, back and forth against model buildings to test how the buildings would react during an earthquake. Geotechnical centrifuge, on the other hand, rotates the soil in the ground at a very high speed to simulate the waves of an earthquake.
In the near future, experiments will test the effects of seismic waves on a variety of building materials, including steel, reinforced concrete, precast concrete, prestressed concrete, fiber reinforced polymer concrete, wood, electrical cables, and masonry. Researchers hope that the findings will aid engineers in designing stronger structures and building supplies. Mujumdar said that he hopes the studies will help engineers design safer, more earthquake resistant buildings.
To find out more about the NEES network and its earthquake test results, click on the link to the right.