Lehigh University
Lehigh University


ATLSS student seeks to help buildings bend, not break, during earthquakes

The Long Beach Earthquake of 1933 killed 120 people, destroyed 70 schools, and caused over $40 million in damage.

It also awoke America's engineers and architects to the need for special designs to protect buildings from earthquakes, says Larry Fahnestock.

Larry, a Ph.D. student in civil engineering, studies ways of designing buildings so they deform in a planned manner - bending rather than breaking - during an earthquake, and can be quickly and cost-effectively returned to service.

He is particularly interested in buckling-restrained braced frames (BRBFs), whose diagonal braces resist lateral loads and help minimize the damage to buildings during earthquakes.

BRBFs have been used in Japan for many years and have recently been installed in some buildings in the U.S. Part of a trend called performance-based design, BRBFs reflect efforts by engineers to anticipate, minimize, and control the location of damage that earthquakes cause to buildings.

A BRBF is made of two pieces - a steel plate core surrounded by a concrete-filled steel tube. The steel core is "de-bonded" from the concrete so that it sustains the entire load of an earthquake. It does this by elongating and compressing within the concrete, which prevents the core from buckling.

Larry's research is related to a larger project at Lehigh, led by James Ricles, professor of civil engineering, which is supported by a $2.6-million grant from the National Science Foundation's George E. Brown Jr. Network for Earthquake Engineering Simulation (NEES) program.

With this grant, Lehigh's ATLSS Engineering Research Center, the nation's leading facility for the large-scale testing of structures, is building a state-of-the-art lab to test the response of structures to the strongest earthquakes.

Larry has conducted research using DRAIN-2DX, a software program that simulates the effects of earthquakes of varying intensities on a structure and the structure's performance during an event.

Based on the findings from his computer simulations, Larry wrote a paper with three Lehigh civil engineering professors - Richard Sause and James Ricles, his Ph.D. advisers, and Le-Wu Lu. The paper, titled "Ductility demands on buckling-restrained braced frames under earthquake loading," was published in December 2003 in the journal Earthquake Engineering and Engineering Vibration and has been widely read, says Larry.

"There's potential for our work to influence aspects of national building codes. It's great to see my research having an impact on what's going on in structural engineering practice."

Later in 2004, Larry will use the results of the simulated tests to conduct actual tests in ATLSS's Large-Scale Multidirectional Lab, which contains a 12-by-30-meter strong floor and an L-shaped reaction wall up to 15 meters tall. The lab has the ability to test a four-story-high structure scaled down to 60 percent.

Larry has had the opportunity to present his research at several conferences.. In February 2004, he gave a presentation on his research at the annual meeting of the Earthquake Engineering Research Institute (EERI) in Los Angeles. He also was awarded an NSF travel fellowship to go to The Netherlands in June 2004 for The Fifth International Ph.D. Symposium in Civil Engineering, which allows students to present their research and meet their peers. Larry discussed the results of his analytical studies.

In 2002, Larry won a national graduate fellowship from EERI and the Federal Emergency Management Agency. Previously he received the Klingelhofer Award from the American Institute of Steel Construction.

Larry, who hopes one day to work as a university professor and researcher, attributes much of his success to his advisers.

Lehigh's Ph.D. program in civil engineering, he says, "is very demanding. Prof. Sause and Prof. Ricles have high expectations. But having to work hard forces me to learn what I will need for the future. I'm looking forward to doing research, teaching students and coming up with new ideas myself. The only way I can learn that process is by doing it."

Posted on Sunday, August 01, 2004

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