METHOD AND DEVICE FOR MEASURING CRACK DEPTH OF REINFORCED CONCRETE STRUCTURE

摘要

PURPOSE: To accurately measure crack depth regardless of the presence/absence of steel by identifying a signal within a specific frequency range from a reception wave and performing inverse Fourier transformation of the signal. CONSTITUTION: A pair of ultrasonic transmission sensors 6 and ultrasonic reception sensor 7 are arranged while holding a crack 13 for transmitting and receiving signal and the obtained reception signal wave is subjected to Fourier transformation. The obtained Fourier spectrum includes a frequency wherein a spectrum value greatly changes according to a measurement position and a frequency wherein a spectrum value hardly changes. Then, a frequency range where the spectrum value hardly changes is selected and inverse Fourier transformation is performed, thus reducing steel-path wave, repeatedly performing Fourier transformation and inverse Fourier transformation for time-series waveform containing a number of crack-path components for bundling, thus obtaining a time-series waveform consisting of crack-path components.