以應力波法非破壞檢測混凝土植筋epoxy握裹長度

Use of Stress Wave methods for Nondestructive Inspection of Epoxy-Bonded Length of Post-installed Rebars in Concrete

10.6849/SE.201809_33(3).0002

鄧凱均(Kai-Chung Teng)；莊江隆(Chiang-Lung Chuang)；林宜清(Yiching Lin)；江國睿(Guo-Ruei Jiang)

植筋品質 ； 非破壞檢測 ； 應力波動 ； 敲擊回音法 ； quality of planting bars ； nondestructive evaluation ； stress waves ； impact-echo

結構工程

33卷3期（2018 / 09 / 01）

27 - 41

繁體中文

本文開發以波動技術非破壞檢測植筋握裹長度與植筋深度。首先以有限元素法對植筋結構之應力波動訊號進行數值模擬分析，以瞭解植筋之波動行為，並經由植筋試體之敲擊回音試驗來驗證數值分析結果。研究結果顯示，在頻譜圖中可以發現明顯尖峰位於主導頻率上，該主導頻率主要由植筋外露長度與植筋握裹長度所控制，對特定之植筋外露長度時，植筋握裹長度越長所得頻率就越高。本文以數值分析建立三種不同植筋外露長度（10、15與20公分），頻率與植筋握裹長度間之關係曲線。試驗檢測結果與數值模擬相當吻合。研究結果建議現場植筋握裹長度檢測程序如下：(1)以超音波測得植筋總長度，由測得之植筋總長度扣除外露長度即可求得植筋深度；(2)執行敲擊回音試驗測得主導頻率，代入所建立的迴歸方程式，即可以預估植筋握裹長度。試驗結果顯示預估之植筋握裹長度誤差大都在1公分以內，證明本文所開發檢測法可以作為現地植筋施工品質之檢驗用。

This article develops a stress wave-based technology to detect non-destructively the epoxy-bonded length and embedded depth of post-installed rebars in concrete. Firstly, the finite element method (FEM) was used to simulate the stress wave propagation signal of the post-installed rebars in concrete to understand the wave propagation behavior of anchorage rebar. The results of the numerical analysis were verified by the impact-echo test performed on the concrete specimens containing post-installed rebars. The results show that a high amplitude peak can be found at the dominant frequency in the spectrum. The dominant frequency is mainly controlled by the exposed length and the epoxy-bonded length of the post-installed rebar. For a specific exposed length of the planting rebar, the longer the epoxy-bonded length, the higher the dominant frequency. In this paper, numerical analysis of three different exposed lengths (10, 15 and 20 cm) were considered to establish the relationship between the dominant frequency and the epoxy-bonded length. The experimental results are in good agreement with those obtained from the numerical simulation. The results obtained from this study suggested that the epoxy-bonded length of post-installed rebar can be evaluated as follows: (1) The total length of the post-installed rebar can be measured by ultrasound. The embedded depth of the post-installed rebar is obtained by deducting the exposed length from the measured total length; (2) Impact-echo test measured the dominant frequency. The epoxy-bonded length can be predicted by substituting the dominant frequency into the established regression equation. The test results show that the estimated error of embedding length of post-installed rebar is mostly within 1 cm, which proves that the test method developed in this paper can be used to evaluate the quality of planting bars.

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