インパクトエコー法によるPCグラウト充てん度評価に関する考察(<特集>建設材料)

概要

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Impact-echo technique is a method for nondestructive evaluation, detecting elastic waves due to a mechanical impact. Although the impact-echo is reported to be promising for quantitative estimation, an applicability to evaluation of post-tensioning tendon ducts is not confirmed yet. To this end, the basic theory of the impact-echo should be clarified. In this paper, a specimen containing an ungrouted duct is tested. Theoretically, frequency responses of the specimen depend on the size, orientation of the void, and P-wave velocity, while wave motions in concrete structures are characterized by material properties, incident waves, and size of members. Thus, the frequency response is studied from the relationship between the wave length and the depth of duct. Experimentally, impact tests are conducted by dropping steel balls and shooting aluminum bullets. The analysis is carried by the boundary element method(BEM). As a result, the detection of resonance frequency due to the presence of void is clarified, relating with impact frequencies and the depth of duct.
1999-08-15