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Nakagawa M.,Tokyo University of Science | Sato D.,Tokyo University of Science | Nagae T.,EERC | Kitamura H.,Tokyo University of Science | Sano T.,Obayashi Corporation
AIJ Journal of Technology and Design | Year: 2013

According to the past researches, the structural damage of high-rise steel building when subjected to long-period ground motions is characterized by the concentration of deformation to beam-column connections. In addition, it is known the field weld connection details tend to have poor deformation capacity. So far, there is no comprehensive data base about beam-column connection details of existing high-rise buildings. This study provides a data base of high-rise steel buildings, focusing on the beam-column connection details. Source


Okazaki T.,Hokkaido University | Matsumiya T.,Kinki University | Nagae T.,EERC | Fukuyama K.,EERC | And 2 more authors.
Journal of Structural and Construction Engineering | Year: 2013

Two full-scale steel moment-resisting frames were constructed and tested at E-Defense to examine the performance of high-rise buildings subjected to long-period ground motions. Frame 1 adopted typical design and detailing from the 1970's employing both field- welded and shop-welded details for the moment frame connections. Frame 2 was identical to Frame 1 except that all connections were field-welded and upgraded using three strengthening methods. A number of connections in Frame 1 fractured during a simulated long- period motion. No damage was observed in Frame 2 until the same motion was repeated multiple times. The performance of field- welded connections in existing high-rise buildings and the effectiveness of upgrade methods are discussed. Source


Kato T.,Tokyo University of Science | Sato T.,Tokyo University of Science | Sato D.,EERC | Kitamura H.,Tokyo University of Science | And 3 more authors.
AIJ Journal of Technology and Design | Year: 2014

In assessing to some structural problems of existing high-rise buildings, it is necessary to comprehend states of that precisely. This study focuses on the components and characteristics of that, and constructs the seismic analysis model on basis of typical specifications, which is investigated by literature survey. The analysis result against long-period ground motion shows two suggestions. One is that the seismic performance of existing buildings may not be weak comparing to current buildings, and the other is that the cumulative damage of beam ends concentrates lower stories. Source


Sato D.,Tokyo University of Science | Kitamura H.,Tokyo University of Science | Sato D.,EERC | Sato T.,Tokyo University of Science | And 3 more authors.
Journal of Structural and Construction Engineering | Year: 2014

Structural control devices are widely implemented in order to reduce the seismic response of buildings. These devices are typically categorized as hysteretic dampers and viscous dampers. Generally, a structure employs only one of these two dampers; however, in recent years, a case has been made for using both dampers simultaneously in order to improve seismic performance. For the quantitative evaluation of seismic performance, a prediction method based on energy balance has been proposed in the past studies. However, the existing method cannot be adapted to response control structures composed of two types of dampers. This study proposes a solution to this problem by establishing the theory relating to vertical distribution. Furthermore, a wide range of ground motion characteristics are investigated by using f-value for an energy evaluation of ground motion. The proposed prediction method is validated by comparing its results with those of time-history analyses. In addition, the effectiveness and applicability of using both dampers are verified using the proposed method. Source


Shimada Y.,Tokyo University of Science | Sato D.,Tokyo University of Science | Nagae T.,EERC | Kitamura H.,Tokyo University of Science | And 7 more authors.
Journal of Structural and Construction Engineering | Year: 2010

In long-period ground motions, high-rise buildings are subjected to large cumulative deformations as well as large story drifts. Retrofitting with dampers may be one of the most effective solutions to reduce such seismic responses. This study examines the influences of steel dampers partially installed into the lower part of high-rise buildings. A series of dynamic response analyses are conducted for typical steel high-rise buildings. A long-period ground motion is adopted whose energy spectrum has a peak amplitude at three seconds, and twenty-one story buildings and thirty-five story buildings are substituted by frame models. The results show that the total energy absorption of the dampers installed into forty-percent stories can be equivalent to that of the dampers installed into the whole stories. On the other hand, the maximum drift of the story located right on the lower part having dampers would become 1.4 times larger than those of the lower part. Source

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