結合FEM與系統量測反應之 結構損害偵測

Combine FEM and Response Measurement For Structural Damage Detection

劉建賢(Chien-Hsien Liu)

指導教授 ： 羅俊雄

國立臺灣大學/工學院/土木工程學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.00110

摘要

這篇論文探討藉由使用有限量測結合有限元素理論的整體與局部之系統損害偵測理論，提出的方法包括了三個已經發展完全的階段，第一是使用整體系統的觀點(線性系統)來識別參考結構的動態特性，第二是使用模態應變能改變做結構損害識別，第三是元素識別理論來量化損害程度。
對於結構系統識別，我們使用狀態空間模式識別基礎的SRIM法，其他的方法如FDD也被用來驗證其識別結果的準確性，模態擴充法也被用來將有限量測的模態振型擴充到全自由度，最終使用模態應變能改變比例來識別損害的桿件。

為了量化桿件的損害程度，除了加速度紀錄外，應變量測與位移紀錄也應用上。結合應變基礎的識別，包含變形與剛體運動的狀態變數需要被識別出來，另外除了以桿件勁度改變為基礎的損害識別，我們也提出了改良的模態應變能改變理論，最終使用桿件的反應紀錄，其損害程度可以被估計出來。

而上述方法也應用到使用地震反應的實尺寸三層樓鋼結構，此結構由國家地震中心作為一弱震與強震的模型建物，此外一人造的缺陷也被設計在此模型上以達損害識別的目的，所有上述的方法都用來處理模式基礎的損害識別並驗證其理論。

關鍵字

損害偵測 ； 系統識別 ； 有限元素

並列摘要

This paper presents both global and local system damage detection algorithm by using limited measurements which incorporated with the model-based estimation technique and finite element model method. The proposed approach has three well-developed phases: (1) identification the dynamic characteristics of the reference structure from global point of view (linear system), (2) structural damage detection using modal strain energy changes, (3) quantification of damage through element identification.
For the identification of structural system a state-space model using the information matrix of time-invariant system realization technique (SRIM method) is used, from which the second-order dynamic model parameters from the realized state-space model is also identified. Different approaches, such as FDD method is also applied to verify the accuracy of the identification results. Modal expansion technique was applied to estimate the mode shapes incorporated with all degree of freedoms. Finally, modal strain energy change ratio for each element is calculated from which the damaged element can be identified.
In order to quantify the element damage, not only from the acceleration measurement but also based on the strains and displacement measurements. For the strain data, the state variables of the fundamental first-order form consist of the strains and the elemental rigid body motion amplitude need to be identified. For damage identification, assumed damage is characterized as a reduction of the member stiffness from a known baseline value, the improvement on structural damage quantification algorithm based on the above mentioned element modal strain energy change before and after occurrence of damage is applied. Finally, from the element responses damage can be quantified.
Based on the above-mentioned methods this report present an example of identification and damage detection to a seismic response data of a series of shaking table tests of a full-scale 3-story steel building. This structure was defined by NCREE as a benchmark building which contains the low level and strong level of earthquake excitation. Besides, a man-made fault was also implemented to this benchmark building for damage detection. The above mentioned methods are applied to conduct the model-based damage identification and to verify the proposed algorithms.

並列關鍵字

damage detection ； system identification ； finite element

參考文獻

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