JOINT CONFERENCE PROCEEDINGS 9th International Conference on Urban Earthquake Engineering/ 4th Asia Conference on Earthquake Engineering March 6-8, 2012, Tokyo Institute of Technology, Tokyo, Japan SEISMIC EFFECTS OF THE 2011 TOHOKU, JAPAN EARTHQUAKE ON STEEL BUILDINGS Dimitrios G. Lignos 1) , James M. Ricles 2) , Jay Love 3) , Taichiro Okazaki 4) , and Mitsumasa Midorikawa 5) 1) Assistant Professor, Civil Engineering and Applied Mechanics, McGill University, Canada 2) Professor, ATLSS Engineering Research Center, Lehigh University, Pennsylvania, United States of America 3) Principal, Degenkolb Engineers, San Francisco, California, United States of America 4) Associate Professor, Graduate School of Engineering, Hokkaido University, Japan 5) Professor, Graduate School of Engineering, Hokkaido University, Japan dimitrios.lignos@mcgill.ca, jmr5@lehigh.edu, rjlove@degenkolb.com, tokazaki@eng.hokudai.ac.jp, midorim@eng.hokudai.ac.jp Abstract: This paper summarizes the main observations by the research group, which was dispatched by the Earthquake Engineering Research Institute (EERI) to investigate in collaboration with researchers from the Architectural Institute of Japan (AIJ), the earthquake damage on steel buildings during the Magnitude (M w ) 9.0 event which occurred at 2:46 p.m local time on 11 March 2011, in the western Pacific Ocean off the coast of Japan. The areas of reconnaissance that were performed by the EERI/AIJ team included the Aobayama Campus of Tohoku University, the Oroshimachi area and the Ishinomaki and Onagawa fishing ports. The paper focuses on observed structural damage due to the ground motion shaking in steel-framed reinforced concrete (SRC) buildings, steel parking garages, and industrial/residential buildings. Emphasis is placed on the implications of the seismic design of steel braced frames based on a U.S. perspective. Observations regarding the nonstructural damage of steel buildings due to the ground shaking are also presented with emphasis on cladding and the external façade. 1. INTRODUCTION At 14:46pm on March 11 th 2011, the East Japan Tohoku-Chico Taiheiyo-Oki earthquake of Magnitude M w 9.0 occurred off the Sanriku coast of Japan followed by a large number of aftershocks above Magnitude M w 5. The largest aftershock occurred on April 7 th at 23:32pm having a magnitude of M w 7.1. In addition to the ground motion shaking, all ports and towns along the east Sanriku coast in the pacific coast of the eastern Japan were devastated by a tsunami caused by the main earthquake. The human casualties due to the tsunami exceeded 15,000. The epicenter of the earthquake was located 129km east from Sendai (see Fig. 1), which is the largest city in the northeast part of Japan. The 2011 Tohoku earthquake is the largest earthquake in Japan in terms of magnitude since modern instrumentation recording began 130 years ago (Kasai et al. 2012). However, this earthquake is the fourth largest in the world in terms of magnitude (M w ) since 1900 after the 1960 M w 9.5 Chile, the 1964 M w 9.2 Alaska and the 2004 M w 9.2 Sumatra earthquakes. Figure 1 shows the peak ground accelerations (PGAs) recorded during the main earthquake event (March 2011) as summarized by the Earthquake Research Institute (ERI). This map shows that excessive ground motions in terms of PGA were recorded near Fukushima (PGA = 2699cm/s 2 ). From the same figure, strong motions with PGA larger than 200cm/s 2 were recorded from the south Iwate to Ibaraki. After the Tohoku earthquake, the Earthquake Engineering Research Institute (EERI) dispatched a research team to conduct earthquake damage reconnaissance of the steel buildings in the Sendai area in collaboration with investigators from the Architectural Institute of Japan (AIJ). Figure 1 Distribution of PGAs in eastern Japan during the 2011 Tohoku-Chico Taiheiyo-Oki earthquake Figure 2 shows the areas of reconnaissance by the EERI/AIJ