利用打音法及頻譜分析診斷建築物外牆磁磚劣化之研究

Abstract

磁磚是臺灣常見的建築物外牆裝飾材料，具有保護內部結構及美化建築物的功能，不過自建築物新建完成起，便開始受到自然的劣化行為，近年來，臺灣建築物外牆磁磚剝落的現象不斷，不僅造成建築物美觀上的受損，也影響了用路人的生命安全及財產安全。 由於全面更新外牆磁磚的費用昂貴，因此決定是否更新外牆磁磚之前，建議先做外牆磁磚的健康狀況診斷。檢測方式分為兩大類，分別為破壞性檢測及非破壞性檢測，非破壞性檢測對建築物的外觀及功能上影響較小，對於全面性的檢測是較合適的，其中又以打音法為現階段準確性較高的檢測方式，也有操作容易的優點，不過此方式得由有經驗的檢測人員主觀判斷，無法以客觀科學的方式判斷及記錄，因此缺乏一個一致性的判斷準則以及可供參考的統計結果，也會有因檢測人員的不同造成檢測結果不一致的情形，此外，若檢測人員的精神狀況不佳或耳朵長時間的使用，都會使聽覺的靈敏度喪失，造成檢測結果不甚準確。 因此本研究認為需要以一套科學的方式來改善現階段打音法使用上的缺點，本研究設計固定敲擊力道及固定收音距離裝置，並使用指向性電容式麥克風收音，接著將收集到的聲音做音訊前處理，再透過MATLAB撰寫程式，利用快速傅立葉變換(FFT)來分析、探討正常磁磚與劣化磁磚之區別。 本研究建立了三種模式，分別為最高峰值、最高峰對應頻率及標準化後頻譜面積，並選用了五棟實體建築物作為案例，以探討這三種模式在實務上的應用，藉此將能以科學的方式量化音訊，解決了打音法得由有經驗的檢測人員主觀判斷的缺點，最終建立一套打音法作業流程，並期望本研究之研究成果能提供公部門納入修法時之參考，作為使用打音法診斷建築物外牆磁磚之劣化基準，或提供評估檢查人員在建築物外牆磁磚劣化診斷時使用

The ceramic tile is a decorating material which is widely used on buildings in Taiwan. It has the functions of protecting internal structures and beautifying buildings. However, the ceramic tile will deteriorate due to natural factors which may cause it scaling off to affect the public safety. As a result of the high cost of repairing external walls, the study suggests diagnosing the condition of ceramic tile as priority. The non-destructive test is proper to do it because of lightly affecting to the structure. Nowadays, tap tone method is a type of test with higher accuracy. Nevertheless, the testing result has no consistency by reason of the subjective judgement of the tester. Besides, it will lose accuracy if the tester is in a bad psychological state. Therefore, the research considers there should be a set of scientific way to improve the disadvantages of tap tone method. It invents an instrument which can produce consistent impact and sound receiving distance. Furthermore, the study uses Directional Condenser Microphone to collect the sound and programs with MATLAB to do FFT analysis to distinguish whether the ceramic tile deteriorates. The study establishes 3 assessment models: the peak value, the frequency of the peak and the area of spectrum after standardization. It chooses 5 buildings as cases to discuss the application of 3 assessment models. By doing so, the sound can be quantified by scientifically way. It solves the problem of subjective judgement of the tester. Finally, the research sets up a standard process of the tap tone method and expects its result can provide the Government as reference when it revises the law.