Array-Measurement-Based Algorithm for Detecting Debonded Regions between Concrete Matrix and Steel Reinforcing Bars in Concrete Samples

摘要

The objective of this study is to develop an array measurement-based algorithm to identifydebonded regions between the concrete matrix and steel reinforcing bars of concretestructures. In the proposed procedure, an impact hammer excites one end of a concretesample and a tri-axial accelerometer is then used to measure the resulting vibrationresponses on both end surfaces of the sample. Then, a MUltiple SIgnal Classification(MUSIC) algorithm is used to locate the debonded regions as “passive” sources wherereflective waves are generated. In order to suppress the effects of the direct wavesgenerated from the excitation as well as the reflective waves from the boundaries at theends of the sample that make it almost impossible to detect the subtle reflective waves fromthe debonded region, modified steering vectors are calculated from a finite element modelof the sample including the effects of the direct and boundary-reflective waves. Then, themodified steering vectors are used to scan the concrete sample and calculate a 2-D MUSIC power map. By applying the proposed algorithm to both experimental and numerical data,it is shown that the proposed algorithm can be used to successfully detect the debondedregions of the concrete sample.