| Summary: | 碩士 === 國立臺灣大學 === 土木工程學研究所 === 101 === The objective of the research is to establish a system identification procedure of building with mid-story isolation, expecting to identify meaningful and physical parameters of building with a simplified model. We use lump mass method, simplifying a building with mid-story isolation into a four lump mass system. Respectively, these are superstructure, floor above isolation system, substructure and equivalent foundation. And we consider there are three degrees of freedom (longitudinal, transverse and torsional) in every lump mass, total of twelve degrees of freedom. For the superstructure, we use effective modal mass method to simplify multiple degrees of freedom system, and consider torsional coupling effect with it. Bilinear mechanical behavior assumed in isolation story with LRB, following the Skeleton curve in Masing Rule. Besides, in equivalent foundation, we describe the soil-structure interaction system with the Soil Spring Method. Soil and structure are simplified impedance between the effective spring and damping, and assume that the reaction is a non-linear response, following the Bouc-Wen Modal. We use the concept of least square method in the identification. This is a non-linear least square problem because there two eccentricities in superstructure. Therefore, we used Levenberg-Marquardt algorithm to solve non-linear least square problem.
In numerical example, we estimated the structure parameter with twelve degrees of freedom of mid-story isolation building modal. Next, we input El Centro earthquake and calculated dynamics response of all degrees of freedom by Newmarkβ linear acceleration method. Subsequently, regarding the behavior of each degree of freedom as measurement data, the identification procedure is executed to verify the suitability of identification theory and modified identification model.
The data gathered by strong motion instrumentation program in the New Research Building of Civil Engineering department of National Taiwan University is adopted as measurement data to implement practical analysis, both the single and multi-section identification are accomplished and discussed in the research. Finally, the reliability of the identification procedure is verified by calculating the error index between the result of identification procedure and measurement data.
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