An experimental research on three-dimensional waves in a concrete panel

An experimental verification of three-dimensional waves is performed to determine the correct group velocity of guided wave in a concrete panel used as part of precast structural diaphragm walls. A frequency-controlled method is applied to induce the guided wave with central frequency as high as 25 kHz in the concrete panel. The measured acceleration waveforms are transformed into spectrograms with the joint time-frequency analysis. A mode identification method is then developed in which the experimental data associated with dispersive group velocity are plotted and compared with the theoretical group velocity-frequency plot to determine the correct dispersion modes and its corresponding group velocities among these induced waves. Experimental results show the validity of the proposed method. Such method has the potential for use as a non-destructive testing technique to assess the material quality of concrete panel.