NZSEE Webinar – Japanese building retrofit schemes using dampers for various seismically defective buildings | Online

Abstract: This presentation discusses Japanese retrofit schemes using dampers for various seismically defective buildings, typically of reinforced concrete (RC) construction.  Seven types of dampers (steel, friction, oil, viscous, linear viscoelastic, nonlinear viscoelastic, and inertial-mass dampers) used in Japan are briefly explained.  Various frame systems supporting the dampers are categorised, and their vibration control effectiveness is explained. The retrofit scheme is also briefly characterised by the selected combination of the damper and frame system. At first, retrofit schemes including conventional ones to increase member stiffness, strength, and ductility are overviewed.  At second, three example projects using the dampers and the supporting frames are demonstrated. At third, the presenter’s experimental and analytical studies on torsional response control are briefly presented for the buildings with significant mass, stiffness, and/or strength eccentricity, commonly seen at the street corner. They are followed by the two example projects assisted by the presenter using dampers to mitigate torsional damage/collapse of such defective buildings.

Presenter Bio:

Dr. Kazuhiko Kasai, Professor Emeritus, Institute of Science Tokyo(formerly Tokyo Institute of Technology) is an internationally recognised researcher and educator in the areas of steel structure, response control, and earthquake engineering. He obtained a Ph.D degree in 1985 from the Structural Engineering and Structural Mechanics Division, Univ. of California, Berkeley.  He conducted many research projects in US and later in Japan, with the total budget of the research exceeding 20 million dollars. For more than 20 years, Prof. Kasai served as the chairman of various committees on passive control and steel structures for Japan Society of Seismic Isolation (JSSI), Architectural Institute of Japan (AIJ), and others.

Prof. Kasai was the Japan-side leader of the US-Japan (NEES and E- Defense) steel building research projects including E-Defense full-scale tests of conventional structure and value-added or response-controlled structures, as well as the Strategic China-Japan Cooperative Program on tall buildings. Prof. Kasai was the chief editor for “JSSI Manual for Design and Construction of Passively Controlled Building”,1st to 3rd editions. He is currently the president of the House Seismic Vibration Control Consortium addressing seismic protection of houses in Japan, and has published the “Vibration Control Manual for Residential Buildings”, 1st edition.

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