位移頻率響應函數於房屋結構健康監測之應用

Abstract

結構物健康監測概念已行之有年，近期由於非接觸監測方法可提供全域之應變量測且施作方式簡便而受到各界重視。數位影像相關係數法為一非接觸式的量測技術，因此本研究提出一套結合影像相關係數法及結構位移反應分析方法之結構健康監測系統。此架構主體包含了影像處理、數值分析及損壞診斷。研究中首先使用SAP2000軟體建立數值模型，以數值模擬獲得模型在受地震力擾動下的位移資料，實驗部分則利用NCREE一棟八層樓之鋼結構模型，使用數位影像相關係數法之擷取方式，對此實驗模型進行動態資料之擷取其位移資料。在結構模型實驗中將所識別之子結構頻率響應函數值以損壞指標公式量化損壞程度與設計之損壞案例做比對，說明及驗證子結構頻率響應函數之適用性及可行性。分析結果顯示，本研究提出的曲率法改良式子結構頻率響應函數方法，其結果在數值模擬與現地實驗中對於損壞案例指標值較為敏感。此方法在不連續損壞位置的損壞案例上有良好的效果，但遇到連續位置將無法做正確的判別。

Recently, non-contact measurement technique has received considerable interest that provides accurate measurements of the full field strain distribution, and the process of the approach is simple. This study proposes a structural health monitoring (SHM) system which combined DIC method and a displacement-based structural frequency response function (FRF) analysis method. The system includes three sub-systems, image processing, and numerical simulation analysis and damage diagnosis. A numerical study is first employed to evaluate the validation and performance of the proposed system. An eight-story steel structure was then used as an experiment modal and examined on NCREE via DIC technique to detect the simulated damage of steel frame. Also, a modified curvature of sub-structure FRF (subFRF) approach is developed to detect damage location of structures. In experiment, the index of subFRF is used for evaluation and identification of the damage location. The results from different approaches and data acquisition methods are compared in order to demonstrate the applicability of sub-structure FRF method to structural health monitoring. The simulation and experiment results reveal that the modified subFRF curvature method is more sensitive in experiment than numerical simulations. Also, simulation results indicate that this method has better performance on the discontinuous damage locations of damage cases, but encounter continuous positions would not be able to do the correct judgment.