考慮土壤結構互制之中間層隔震建築系統識別

Abstract

本文旨在建立一個中間層隔震建築的分析模式與其識別流程，期能以一簡化的模型識別出結構物具物理意義的參數。文中在以集中質量的方式，且僅考慮水平單軸方向位移的假設下，將一包含地下室結構的中間層隔震建築簡化為四個自由度的系統，這些自由度分別為上部結構水平單軸方向位移、隔震層上方樓版水平單軸方向位移、下部結構水平單軸方向位移及等值基礎水平單軸方向位移。其中上部結構以等效線性模態質量法將多自由度系統轉換為單自由度系統。分析時，假設上部結構及下部結構之力學行為為線性，而隔震層的LRB行為則是非線性，並以Masing準則加以描述，簡化為雙線性模式。此外，建築物與土壤的互制作用則以一組等值的勁度及阻尼模擬，以經驗公式求取適當的等值基礎參數，並假設基礎的力學行為為線性。 利用輸出誤差法(Output-error method)在個別自由度處，識別出上部結構、下部結構及等值基礎的線性參數，以及LRB的非線性參數。此處改變以往必須先固定某一參數識別另一參數的識別流程，而以同時識別兩個參數的作法，改進識別的精確度並減少手動作業的次數，降低人為錯誤發生的機率。 最後，藉由台大土木新系館ETABS模型執行ETABS程式動力分析所取得的歷時資料作為實例識別之量測值，進行實例分析。經由識別結果與量測歷時間誤差指標的計算，以驗證識別流程的可靠性。

This thesis constructs a system identification procedure of buildings with mid-story isolation, expecting to identify physical parameters of a building with a simplified model. We used lump mass method, considering only single axial horizontal degree of freedom. With these assumptions, we can simplify a building with mid-story isolation include basement structure into a four degree of freedom system. These degrees of freedom are superstructure, floor above isolation system, substructure and equivalent foundation. For the superstructure, concepts of effective modal mass and effective modal height are adopted to simplify multiple degrees of freedom to single degree of freedom. Linear mechanical behavior is assumed in superstructure and substructure; nonlinear mechanical behavior is assumed in isolation story, meanwhile simplified into bilinear behavior with Masing criteria. Besides, a set of equivalent damping and spring, assumed to have linear mechanical behavior, was adopted to simulate soil-structure interaction, estimating proper equivalent foundation parameters with empirical equations. Output-error method was applied to identify linear and bilinear parameters of all degrees of freedom. Different from previous researches which demands to fix a certain parameter in order to obtain the other, this thesis obtains both parameters at the same time. The advantages of this procedure are: improvement of the identity value accuracy; and decreasing of manual control errors. Finally, the reliability of the present procedure was verified by calculating the error index between the results from the present procedure and ETABS’s dynamic analysis of the new Civil Engineering Building at NTU.