In this study, a viscoelastic damper (VED) is developed by using a VE material with low temperature dependence, and a performance-based placement-design procedure of VEDs is developed for finding the story-wise distribution of VEDs in a building such that each peak interstory drift coincides with the prescribed value. The mechanical properties of the employed VEDs dependence on amplitude and frequency of the excitation as well as material temperature are taken into account and a mechanical non-linear four-element model that comprises two dashpot elements and two spring elements is proposed for the VED. The developed performance-based design procedure utilizes equivalent linearization of the VED and the expanded complete quadratic combination method, which involves modal analysis with complex eigenvalue analysis. An equivalent linear Voigt model of the VED is determined by the prescribed peak interstory drift and the fundamental natural period of the structure for which the VEDs are installed. Seismic response analyses are carried out for high-rise building models installed with the necessary number of walltype VEDs, with the results demonstrating the effectiveness and validity of the proposed performance-based placement-design procedure.
This paper presents a performance-based placement design method for the control of the earthquake responses of a multistory building using tuned electromagnetic inertial mass dampers (T-EIMDs). The T-EIMD consists of a ball screw mechanism, a gear, a flywheel, and an electric generator installed in a cylinder, and a spring element connected in series. The ball screw mechanism converts the axial oscillation of the rod end into the rotational motion of the internal flywheel and generates a large inertial force. The electric generator is turned by the rotation of the inner rod and generates a variable damping force that is controlled by the terminal resistance. The T-EIMDs are installed between adjacent floors of a building with steel chevron braces and function as large tuned mass dampers within the stories. The spring element has the function of tuning the natural period of the T-EIMD to the fundamental natural period of the building. In the present work, a design procedure for the story-wise placement of T-EIMDs is proposed to limit the peak story drift angles to a specified target value. The proposed procedure utilizes the expanded complete quadratic combination method that involves modal analysis with complex eigenvalue analysis and is able to determine the necessary story-wise distribution of inertial masses of the T-EIMDs in a building. Time history earthquake response analyses are carried out for multistory building models set up with the necessary number of T-EIMD units, and the results establish the effectiveness and the adequacy of the proposed performance-based placement design procedure.
RIMD (Rotating Inertia Mass Damper) has been developed to mitigate an earthquake response of structure. Three type of RIMDs, which were a parallel connecting type, a series connecting type and both combined connecting type, for SDOF system were studied by comparing frequency transfer functions for various excitation patterns. The proposed combined connecting type was found to be able to suppress the response in wider frequency range compared with a conventional TMD. The parallel connecting type well reduced the absorbed energy amounts for the earthquake excitations.
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