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Nishi-Tokyo-shi, Japan

Ikago K.,Tohoku University | Ikenaga M.,Tohoku University | Nakaminami S.,Aseismic Devices Co. | Saito K.,Nippon Telegraph and Telephone | Inoue N.,Tohoku University
Civil-Comp Proceedings | Year: 2014

The inerter, which brought about new response control strategies for civil engineering structures, is a mechanical device that generates an inertial resistance force proportional to the relative accelerations between its two nodes. One of the most viable ways to implement the idea of the inerter is to utilize a ball screw mechanism; indeed, rotary inertial dampers for seismic control and seismic isolation having apparent masses of 5, 400 and 1, 250T, respectively, have been successfully developed in Japan. Although incorporating a rotary inertial damper is effective for reducing relative displacements, it induces high floor response accelerations, which transmit ground accelerations directly to the superstructure. To mitigate the floor response accelerations without deteriorating the reduction of relative displacements, incorporation of a damping force restriction and buffer spring is proposed. This paper reports the results of shake table tests on a small-scale, base-isolated specimen containing an inerter-like device, namely, a force-restricted viscous mass damper, with the aims to validate the analytical methods and to confirm the effectiveness of the force restriction and buffer spring in reducing floor response accelerations. © Civil-Comp Press, 2014. Source


Patent
Aseismic Devices Co. and Thk Co. | Date: 2011-10-20

The screw motion mechanism includes: a threaded shaft having an outer peripheral surface provided with a helical thread groove, the threaded shaft having at least one axial end coupled to a first structural body; a nut member held in a rotatable manner with respect to a second structural body which is movable in an axial direction of the threaded shaft with respect to the first structural body, the nut member being threadedly engaged with the threaded shaft; and a spherical joint for coupling the at least one axial end of the threaded shaft to the first structural body, the spherical joint including: a spherical portion; and a sphere receiving portion for housing the spherical portion. When assuming an axial force applied to the threaded shaft as a variable, a line of a rotational torque intersects with a line of a sliding torque in a graph.


Patent
Aseismic Devices Co. and Thk Co. | Date: 2011-10-19

The damping device includes: a fixed cylinder that is configured to be fixed to a first structural body and formed into a cylindrical shape so as to comprise a hollow portion; a shaft member that is configured to be fixed to a second structural body, the shaft member being housed in the hollow portion of the fixed cylinder and having an outer peripheral surface provided with a helical thread groove; a nut member that is threadedly engaged with the shaft member, and converts an axial motion of the shaft member into a rotational motion; a rotor member that is formed into a cylindrical shape so as to cover the fixed cylinder and to form a cylindrical accommodation chamber between the rotor member and an outer peripheral surface of the fixed cylinder, and is rotated by the nut member; and viscous fluid that is sealed in the cylindrical accommodation chamber.


Kida H.,Aseismic Devices Co. | Watanabe Y.,THK Co. | Nakaminami S.,Aseismic Devices Co. | Tanaka H.,Aseismic Devices Co. | And 4 more authors.
Journal of Structural and Construction Engineering | Year: 2011

The authors have proposed the tuned viscous mass damper system based on the fixed points theory, and have proved the validity of the theory and the analysis method through the vibration tests of the small scale test specimen. The testing program revealed that an increase in equivalent inertial mass of viscous mass damper and increase in input resulted in an excessive stresses in the supporting member, damper body and the primary structure connected to the damper. In this paper, authors built the rotation slipping mechanism into the main body of the full-scale tuned viscous mass damper with the spring member of 18,200kN m and the equivalent inertial mass of 1,35Oton, and tested the tuned viscous mass damper with the force restriction mechanism. Analysis parameters of the tuned viscous mass damper with the force restriction mechanism were evaluated accurately and the test results corresponded well with the analytical results. From the analysis results for a 1-story structure, it is shown that this restriction mechanism can effectively reduce the damper maximum force and the maximum response displacement is almost the same as the result obtained by a restriction-free damper. Source


Kida H.,Aseismic Devices Co. | Nakaminami S.,Aseismic Devices Co. | Tanaka H.,Aseismic Devices Co. | Watanabe Y.,THK Co. | And 3 more authors.
AIJ Journal of Technology and Design | Year: 2013

The authors have conducted full-scale dynamic tests of the largest forcerestricted tuned viscous mass damper (FRTVMD), and analyses of a single-degree-of-freedom structure incorporated with the FRTVMD. A comparison verified the validity of the linearization method for a nonlinear viscous element in the FRTVMD. Source

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