 UNCERTAINTIES OF LONG-PERIOD GROUND MOTION AND ITS IMPACT ON BUILDING STRUCTURAL DESIGN Izuru TAKEWAKI 1 , Kohei FUJITA 2 and Shinta YOSHITOMI 3 1 Professor, Department of Architecture and Architectural Engineering, Kyoto University, Kyoto, Japan, takewaki@archi.kyoto-u.ac.jp 2 Graduate Student, Department of Architecture and Architectural Engineering, Kyoto University, Kyoto, Japan, fm.fujita@archi.kyoto-u.ac.jp 3 Asst. Professor, Department of Architecture and Architectural Engineering, Kyoto University Kyoto, Japan, yoshitomi@archi.kyoto-u.ac.jp ABSTRACT: On March 11, 2011, Japan was shaken by the 2011 off the Pacific coast of Tohoku earthquake (the Great East Japan Earthquake). This paper reports some aspects of this earthquake and its impact on building structural design. It was reported that long-period ground motions were induced in Tokyo, Nagoya and Osaka. The response of high-rise buildings to the recorded ground motions during this earthquake and the simulated ground motions provided by the Japanese Government is discussed from the viewpoint of resonance and critical excitation. Key Words: Great East Japan earthquake, long-period ground motion, resonance, critical excitation, earthquake input energy, passively controlled structure INTRODUCTION The most devastating earthquake in Japan after the 1923 Great Kanto earthquake occurred on March 11, 2011 (AIJ 2011a, b, USGS 2011). The moment magnitude was 9.0 and this is the largest so far in Japan. The earthquake resulted from the thrust faulting near the subduction zone plate boundary between the Pacific and North America Plates (AIJ 2011a, b, USGS 2011). Nearly 20,000 people were killed or are still missing by that earthquake and the subsequent monster tsunami as of November 1, 2011. Because super high-rise buildings in mega cities in Japan had never been shaken by the so-called long-period ground motions with high intensities, the response of high-rise buildings to such long-period ground motions is one of the most controversial subjects in the field of earthquake-resistant design in Japan (MLIT 2010). The issue of long-period ground motion and its effect on building structural design was initially brought up in Mexico, USA and Japan during 1980-1990s (for example Earthquake Spectra 1988, Heaton et al. 1995, Kamae et al. 2004, Ariga et al. Proceedings of the International Symposium on Engineering Lessons Learned from the 2011 Great East Japan Earthquake, March 1-4, 2012, Tokyo, Japan 1005