Title: Moment Tensor Analysis of Acoustic Emission for Cracking Mechanisms in Concrete

Author(s): Masayasu Ohtsu, Takahisa Okamoto, and Shigenori Yuyama

Publication: Structural Journal

Volume: 95

Issue: 2

Appears on pages(s): 87-95

Keywords: acoustic emission; cracking mechanisms; moment tensor analysis; nondestructive testing;

DOI: 10.14359/529

Date: 3/1/1998

Abstract:
A quantitative analysis of acoustic emission (AE) waveforms, which was developed as a SiGMA (Simplified Green’s Function for Moment Tensor Analysis) code, is revised. By the analysis, cracks of AE sources are located, classified into a tensile crack and a shear crack, and their orientations are determined. For practical application to concrete, both experimental and analytical procedures are reexamined on the basis of the background theory of moment tensor. To apply the SiGMA analysis to AE waveforms recorded, a basic experimental procedure is discussed and established. In the tensile test of an L-shaped reinforced concrete (RC) model, nondestructive evaluation (NDE) of cracking mechanisms is investigated. To improve the accuracy of SiGMA solutions, a post-analysis is developed. Unreliable solutions are screened out, based on the discrepancy between SiGMA solutions of the experiment and those of synthesized waveforms. The mechanisms of the fracture process zone are studied in the bending test of a notched mortar beam. These results demonstrate the applicability of the moment tensor analysis to both NDE of concrete structures and to experimental fracture mechanics in concrete.