Evaluation of simulated transfer functions of concrete plate derived by impact-echo method

In this study, the simulated transfer function of a concrete plate was obtained solely from displacement waveform in an impact-echo test. In the simulated transfer function, the amplitude corresponding to the modal vibration at thickness direction, called the thickness-amplitude, can be consistent during various tests on the same location. An empirical formula was obtained by numerical simulation to predict the thickness-amplitude for given thickness, impact–receiver distance, and P-wave speed. The formula was confirmed experimentally using plates made from various mixed materials with various thicknesses. The differences between the experimental and predicted thickness-amplitude are mostly within 10%. The formula has the potential for quantitative evaluation of the bond between concrete and the substrate layer.