Abstract
The purpose of this study is to establish a method to measure fundamental frequency for the reinforced concrete of which thickness is around 2.5 meters by the Impact Elastic Wave Method. It is considered that earlier studies have not devised a practicable and reproducible method. In this study, passage and arrival time of the multiply reflected P-wave was validated by numerical analysis based on 2D elastic body wave equation and then measuring method and analysis method were proposed. In the result, the measuring method with multiple sensors on the surface of the measured concrete was devised, then the devised measuring method was tested on actual concretes of which thickness are 1.6 meters and around 2.5 meters. As a result, the fundamental frequency of the reinforced concrete is objectively determined by the Fourier Transform of the composed function from cross-correlation functions between the input waveform and measured waveforms by each sensor. In addition, the type of elastic waves is discriminated by measuring phase difference between measured waveforms by each sensor.
