以藍姆波群波速之頻散曲線開發老劣化鋼板補強混凝土結構之快速檢測技術

Development of a Technique for Quick Assessment of the Deterioration of Steel Plate Reinforced RC Structure using the Dispersion Characteristics of Lamb waves

劉宗哲(Tsung-che Liu)

指導教授 ： 鄭家齊

朝陽科技大學/理工學院/營建工程系/碩士(2011年)

摘要

研究中主要以應力波原理為基礎的檢測方法來檢測鋼板補強結構老劣化狀況， 將以頻率-波慢譜所呈現之板波模態檢測較大範圍鋼板可能剝離狀況、並計算板波基本反對稱模態之波長-頻率圖、以表面波譜法之分析方式評估鋼板與混凝土間劣化瑕疵之水平範圍。本研究是以單一接收器與單一敲擊源取得頻散曲線，利用短時傅立葉轉換及影像再分配技術波慢-頻率譜圖，再與DISPERSE程式所得到之理論解作比較分析。結果顯示，A0基本反對稱模態與理論解偏離之最大頻率與水平瑕疵尺寸有關。敲擊與接收測線下方有瑕疵存在，A0基本反對稱模態與無瑕疵區有明顯差異，且隨著缺陷範圍越大，A0模態有漸漸偏向理論解之趨勢，但在較小缺陷範圍內(20 cm以下)，部分結果反應類似。數值模擬與試驗結果顯示A0模態波速隨波長改變之關係，均能判別出鋼板與混凝土間黏結是否完善，數值模擬與試驗對於無缺陷缺區域反應明確，在無缺陷區域施測時，其波速之驟降速度最快、最明顯。

關鍵字

鋼板補強 ； 藍姆波 ； 混凝土結構

並列摘要

In this study, the debonding problem for the steel plate strengthened RC structure is evaluated by the testing method based on the principle of stress wave. The modal representation of Lamb waves in group slowness spectrogram can distinguish large debonding area and obtain the wavelength-frequency diagram of A0 mode. The methodology applies to the SASW test is used for assessing the range of debonds. The study is based on a single receiver with a single tap source testing method to obtain the spectrogram. The spectrogram with a precise image of the lamb-wave dispersion curves were obtained by the short-time Fourier Transfer along with the reassigned technique. The theoretical dispersive curve for the steel plate constructed by the program DISPERS is used for comparison. The maximum frequency of the testing dispersion curve of the A0 fundamental antisymmetric mode deviating from the theoretical one is closely related to the size of the debonding area. Great differences in the A0 dispersion curves exist for test lines with and without flaw underneath. The A0 modal dispersive curve has the tendency closer to the theoretical solution for larger debonding area. However, for small defects with the side lengths between 10-20 cm, the responses are similar. Numerical simulation and experimental results show that the variance in velocity with wavelength for A0 mode, can evaluate the bonding condition between steel plate and concrete. The decrease of velocity is largest and most obvious for test above the well-bonded zone.

並列關鍵字

Steel Plate Reinforced ； Lamb wave ； RC Structure

參考文獻

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