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MCEER Bulletin, Volume 25, Number 1, Spring/Summer 2011

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Volume 25, Number 1, 2011

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Damage to Eccentrically Braced Frames Observed Following the 2011 Christchurch New Zealand Earthquake

Following the the February 21, 2011 earthquake that struck near the city center of Christchurch, Michel Bruneau, Professor, Department of Civil, Structural and Environmental Engineering (CSEE), University at Buffalo (UB), again traveled to New Zealand to assess damage. He surveyed the same area he visited as part of the EERI team following the September 2010 Darfield earthquake, and again focused on damage to bridges and steel buildings. (See the Fall/Winter 2010 issue of the MCEER Bulletin for more information.)

Fractured EBF active link

Fractured EBF active link in the top level of an EBF system in the front face of the atrium in the Pacific Tower, in Christchurch, New Zealand.

Preliminary findings include valuable observations on the performance of steel eccentrically braced frame (EBF) structures. This was the first time that the level of excitation of an earthquake was at least as large as or exceeded the design basis in an area where steel EBFs were used. Many performed very well, but a notable exception is shown in the accompanying photo, where fractures developed in the links of EBF frames. This is the first time this type of damage has been observed following an earthquake. It was also the first opportunity to observe how these types of structures perform in large earthquakes.

Bruneau was joined by Mark Yashinsky, Senior Bridge Engineer, California Department of Transportation, who represented PEER; Roberto Leon, Professor, School of Civil and Environmental Engineering, Georgia Institute of Technology; Greg MacRae, Associate Professor, Civil and Natural Resources Engineering, University of Canterbury; and G. Charles Clifton, Associate Professor of Civil Engineering, Department of Civil and Environmental Engineering, The University of Auckland. He was in New Zealand from February 27 through March 4, 2011.

For more information, visit http://mceer.buffalo.edu/ research/Reconnaissance/New_ Zealand2-21-11/default.asp.