System Identification of Buildings with Mid-Story Isolation Considering Torsional Coupling Effect

本文目的在於建立一套中間層隔震建築物的系統識別流程，期望可以利用簡化的模型識別出具有物理意義的系統參數，並且利用合理的假設將中間層隔震建築物簡化為三個集中質量，分別為上部結構、隔震層上方樓板以及下部結構，其中上部結構的計算是利用等效線性模態質量法將多自由度系統簡化，並在考慮上部偏心扭轉耦合的情況下，各部集中質量皆考慮三個自由度(長向、短向以及扭轉向)，故為一個九自由度系統。而分析上假設上部結構與下部結構皆為線性，而隔震層的LRB力學行為則為雙線性模型。 在識別上利用最小平方法的概念，在上部結構因兩個偏心距的關係，故為非線性最小平方問題。我們利用Levenberg-Marquardt演算法來執行非線性的最小平方問題，並利用Masing準則描述非線性狀況下LRB的力學行為。 在數值驗證方面，代入自行估算之參數值，利用El Centro地震歷時與Newmark線性加速度法求得各自由度動力反應，並以此為量測資料進行識別，以確定識別流程的合理性與可行性。 在實例識別方面，以台大土木研究大樓為識別對象，利用台大土木所新建研究大樓結構物強震監測計畫所收集到的歷時資料，選取其中兩組資料進行識別，求取各自由度的勁度、阻尼與偏心距參數，並且探討其誤差來源的可能性。最後計算量測之歷時資料與識別之歷時資料的誤差指標，以確認此方法在實際應用上的可行性。This thesis constructs a system identification procedure of building with mid-story isolation, expecting to identify physical parameters of a building with a simplified modal. We use lump mass method, simplifying a building with mid-story isolation into a three lump mass system. These are superstructure, floor above isolation system, substructure. For the superstructure, we calculate effective modal mass to simplify multiple degrees of freedom system, and we consider it has torsional coupling effect in superstructure. We consider there are three degrees of freedom (Longitudinal, Transverse and Torsional) in every lump mass .There are nine degrees of freedom in the system. Linear mechanical behavior is assumed in superstructure and substructure; bilinear mechanical behavior is assumed in isolation story. We used the concept of least square method in the identification. This is a nonlinear least square problem because there are two eccentricities in superstructure. We used Levenberg-Marquardt algorithm to solve nonlinear least square problem, and used Masing criteria to describe the mechanical behavior of LRB. In numerical example, we estimated the structural parameter to construct a nine degrees of freedom idealized mid-story isolation building. We input El Centro earthquake and calculated dynamics response of all degrees of freedom by Newmark linear acceleration method. We used the response to identify the structural parameters. By numerical example , we hope to improve accurate of the modal and the reasonable of the procedure. Finally, the reliability of present procedure was verifien by calculating the error index between the measure data and identified results from new Civil Buildind at NTU