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In large earthquakes lately occurred in Japan, such as the 1995 Kobe earthquake, the 2004 Niigata Earthquake and the 2011 Tohoku earthquake, many strong ground motions were recorded and some of their ground velocity were larger than that of the design earthquake ground motions. Although these ground motions are severe for buildings, it is important to prevent buildings from collapsing and to protect lives of people. This paper proposes a seismic response control device which prevents midand low-rise buildings from collapsing at a specific story even when they are subjected to severe ground motions. The proposed device consists of the frame and the passive damper, which are mounted outside of the building. The damper used in this device is an ordinary passive damper, such as the friction damper or the oil damper; however, the method to reduce the seismic response is quite different from ordinary passive energy dissipation systems. When we install this device into the first and the second stories and use the friction damper, the resistance of the damper depends on the difference between the deflection of the first story and that of the second story; therefore, the damper works to equalize the deflection in each story. In the first part of the paper, we constructed the analytical model of the proposed device using a mass-spring-damper system, and then derived the formula which predicts the upper limit resistance of the dampers to perfectly equalize the deflection of all the stories. The prediction formula demands the mass of all the floors, the maximum strength of all the stories of the building and the maximum acceleration of the input ground motion. Through the time history seismic response analysis of four-story steel buildings and two-story wooden houses, we confirmed the validity of the prediction formula. In chapter 5, we conducted the time history seismic response analysis of some of the ordinary four-story steel structures with the proposed devices in order to clear the effectiveness of the device on reducing the maximum story deflection. We confirmed that if the relief resistance of the damper is the same as the upper limit resistance calculated by the abovementioned prediction formula, the devices perfectly equalize the deflection of all the stories and reduce the maximum story deflection. Even if the relief resistances of the dampers are approximately 50% of the upper limit resistance, the story deflections are reduced to a considerable extent without excessive increase of the acceleration response. In the last part, conducted was the time history seismic response analysis of the four-story moment resistant steel frame. The steel frame model is the same as the full scale four-story building, which is designed according to the Japanese Building Standards Act, used in the shake table test at E-Defense in 2007. This building collapses at the first story under severe excitation because of local buckling at the column base of the first story. However, when we mount the devices on the building, the devices disperse the damages to all the stories and prevent the building from collapsing at a specific story. Since the response acceleration doesn’t increase so much when we install the devices to the buildings, we concluded that the proposed structural system is effective to upgrade seismic performance of buildings. Furthermore, this device is also appropriate for seismic strengthening of existing buildings, since it can be mounted from the outside of the buildings. PROPERTIES OF VISCOELASTIC DAMPER UNDER WIND-INDUCED EXCITATION AND SIMPLIFIED EVALUATION METHOD USING SINUSOIDAL-WAVE

SEISMIC RESPONSE CONTROL OF MID- AND LOW-RISE BUILDINGS USING EXTERNAL STORY DEFLECTION CONTROL DEVICES