Tetsuya Hanzawa

Performance-Based Placement of Manufactured Viscoelastic Dampers for Design Response Spectrum

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 storywise distribution of VEDs in a building such that each peak interstory drift coincides with the prescribed value. The mechanical properties of the employed VED’s dependence on amplitude and frequency of the excitation as well as material temperature are taken into account and a mechanical nonlinear 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 (CQC) 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 wall-type VEDs, with the results demonstrating the effectiveness and validity of the proposed performance-based placement-design procedure.

Performance-Based Placement Design of Tuned Electromagnetic Inertial Mass Dampers

This paper presents a performance-based placement design method for the control of the earthquake responses of a multi-story building using tuned electromagnetic inertial mass dampers (T-EIMD). 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 (CQC) 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 multi-story 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.

DEVELOPMENT OF “DIRECT & LINEAR BRACE SYSTEM OF CEILINGS”

When we used a conventional method about the “specific ceiling” because it is necessary to secure a performance established in Ministry of Land, Infrastructure and Transport technical standard, it was necessary to attach many braces. Therefore the conventional method was very difficult to plan the building equipment. The coauthor developed the new earthquake-resistant technique of the “specific ceiling” using a light weight steel frame established in Japanese Industrial Standards. It is the system which we named “Linear brace” and can secure very high rigidity and strength. It was recognized that the earthquake-resistant performance of the ceiling was largely improved.

DYNAMIC TEST ON PARTIALLY REINFORCED CONVENTIONAL CEILINGS AND SIMULATION ANALYSES

In recent years, the collapse of ceilings due to earthquakes has become a serious problem. The authors have proposed the reinforcing method to improve the aseismic performance of conventional ceilings. The proposed method employs the partial reinforcement only around the braces of ceilings, and can be easily and economically applied. The shaking table tests of the partially reinforced ceilings were carried out to investigate dynamic characteristics. The analytical model of the reinforced ceilings is proposed based on the static cyclic loading tests and the simulation analyses were carried out to show the effectiveness of the analytical model.

BASIC STUDY ON DESIGN METHOD FOR VERTICAL VIBRATION CONTROL SYSTEM BY A TMD USING A ROTATING INERTIAL MASS

A tuned mass damper (TMD) using a rotating inertial mass has been developed to reduce vertical vibration of beams and slabs subjected to walking excitations. The newly developed TMD is composed of a spring and a ball screw mechanism with a flywheel. The optimum design parameters of some TMD systems were examined, and their response properties were compared. The optimum design parameters minimize the resonant acceleration response of a main mass. In those systems, the mass of the member to connect with a damper was considered. And the effectiveness of the new TMD system was shown. Finally the new TMD system added a spring for adjustment of the tuning to were proposed, the optimum design parameters were shown.