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including The Conductor, a special section of the Spectrum printed 4 times a year

Murray awarded NSF earthquake design project

By Lynn Nystrom

Spectrum Volume 19 Issue 15 - December 12, 1996

When the Northridge earthquake occurred more than two years ago in California, the construction industry was left in a state of surprise. More than 100 steel-framed buildings, designed to withstand the great tremors, suffered failed connections.

"The failure was unexpected, and it surprised the engineering profession," said Tom Murray, Virginia Tech professor of civil engineering and a leading authority on structural design.

After the Northridge earthquake, the National Science Foundation decided to sponsor a one-year project to study the causes of the failures and to establish alternate-connection designs.

The project was awarded to Murray, the Betts professor of civil engineering, and the topic became the subject of a doctoral dissertation for Ronald Meng, a 22-year veteran of the Marine Corps and a former helicopter pilot.

The welding process was determined to be the main cause for the failures. The steel-framed buildings that failed during the Northridge earthquake had been welded on the construction site, Murray said. The structures expert thought that better quality control could be achieved if the welding of the bonds between the plates and the beams took place in a more controlled environment.

Murray's plan was to use the expansive Virginia Tech Structures and Materials Laboratory, one of the largest facilities of its kind in the country, to conduct their research.

Since the lab is designed for full-scale testing of structural components and systems, it allowed the real-size testing needed to verify their new design procedure. By successfully welding the end-plate connections to the beam inside the lab, "we proved we could achieve much greater quality control," Murray said.

Another consideration Murray and Meng investigated was the expense of welding the connections to the beams in a shop as opposed to in the field. Previously, cost had been the primary deterrent to this change in procedure. But Murray and Meng were able to illustrate how to modify specific construction equipment to make the process more reasonably priced.

Murray and Meng were assisted with this project by Hirschfield Steel of Lynchburg. The company fabricated the beams and plates used by the Virginia Tech researchers. Test specimens were also furnished by Nucor-Yamoto Steel Company and Star Building Systems. Lincoln Arc Welding contributed fabrication material and Butler Research provided auxiliary test data. The American Institute of Steel Construction provided assistance with technical matters.

"The results of this research will allow designers to have their first alternate method of connection from the one that failed during the Northridge earthquake," Murray said.