| Summary: | 碩士 === 國立高雄第一科技大學 === 營建工程研究所 === 99 === Although current seismic technology is capable of preventing building structures from severe earthquake destruction, precision equipment in a building may still be seriously damaged due to the effect of structural dynamic amplification. As a result, it may cause the loss of building functionality. Therefore, for important buildings, the seismic design of equipment is as crucial as the building itself. Although in current design codes there are design formulas to determine the minimum lateral force of nonstructural components, the formulas does not take the dynamic characteristics of the building (where the equipments are installed) into consideration. Thus, for buildings with different frequencies, the design force might be over-conservative or underestimated. Furthermore, seismic resistance ability of equipment can be enhanced by two approaches, namely, restraining and isolation. Current design codes are only applicable to the restraining method.
To enhance seismic performance of equipment in a building and to solve the previously mentioned problems, this article illustrates its research outcome with two parts. The first part focuses on the seismic analysis and reduction strategies of equipment; the second part is devoted to the experimental and theoretical studies on an advanced equipment isolation system. In the first part, a dynamic equation which considers complete equipment-building dynamic characteristics is derived and the modal analysis is carried out. By using the derived modal parameters, the response spectral method and the SRSS modal superposition method, an equipment design formula which is applicable to both equipment restraining and isolation is proposed. By comparing with the results of time history analysis, the proposed formula is more accurate than current seismic design codes for equipment in building structures. Additionally, in order to assist engineers to choose more effective seismic resistance strategies for equipment in buildings, the first part of this article uses 16 seismic ground motions to thoroughly simulate the seismic responses of equipment in structures with different frequencies. Based on the simulated data, more effective seismic resistance strategies for equipments in different structure frequencies and seismic loads are proposed.
On the other hand, to overcome the problem of space limitation for equipments isolation inside a building, the second part of this article introduces an advanced equipment isolation system called a piezoelectric equipment isolation system (PEIS). The PEIS system mainly consists of a sliding platform and a piezoelectric friction damper. The piezoelectric friction damper uses a piezoelectric actuator to control its sliding friction force, and thus is able to reduce the motion of the sliding platform. Meanwhile, to effectively control the PEIS and to minimize the number of sensors needed, this study employs extremely simple control laws which merely requires the feedback of the relative displacement of the isolation system. The result of theoretical study demonstrates that the PEIS system effectively reduces the response of equipment in moderate earthquakes, and is capable of reducing the isolation displacement while maintaining isolation efficiency in earthquakes with larger magnitude. Moreover, the theoretical result is also verified by a shaking table test, in which a prototype PEIS is placed on the top of a steel frame. The test data demonstrates that the theoretical and experimental results are very consistent. Therefore, the feasiblity and effectiveness of the PEIS used for equipment isolation is confirmed.
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