## 2 Materials and Work Method
### Work Method  
Figure 3a shows that the dynamic experiment involved a reaction wall, a 50 ton dynamic actuator, and an axial force system. Before the test, a 15 cm \(\times\) 15 cm grid was painted on the surface of each specimen with white cement. Using an optical measurement system, 34 markers (Figure 3b) were placed on each specimen and the system was set with the three-dimensional coordinates of each marker. The cameras of the 3D measurement system specified a measurement range and captured the marker positions during the loading and unloading process of the specimen. The system transmitted the position and orientation data of markers to the application software, and the three-dimensional coordinates of the markers were used to calculate the deformation of each specimen. Displacement gauges were set on the top and bottom of each specimen to measure the displacement of the foundation (Figure 3a). To quantify the damage, the crack widths were measured using a microscope (model: PEAK 2034-100X) with a resolution of 0.01 mm (Figure 3c). Along with the maximum crack width at a specified peak deformation, its corresponding residual crack width at an applied loading of zero was recorded. The crack type and measurement position were determined as described by [PERSON] et al. [7].  
A piezoelectric sensor set consists of a circular piezoceramic disc, a low-frequency paired cable and a BNC (Bayonet Neill-Concelman) connector. Table 2 presents the parameters of the circular piezoelectric transducer, which had a diameter of 20 mm and a thickness of 1 mm. The positive and negative ends of the cable were connected carefully to the sides of a piezoceramic disc electrode and the other free ends were soldered to the BNC adapter (Figure 4). Piezoelectric ceramics are vulnerable to moisture from fresh concrete, so they were sprayed with a thin black layer of waterproof solution. Before the non-shrinkage mortar was sealed, the piezoelectric-based sensor system was inserted into the prepared drill hole at a depth of 80 mm. Figure 5 shows the installation phases and locations of the four sensor units that were embedded in a column specimen. For each specimen under the applied loading system shown in Figure 3d, the moment of a section near the top end of each specimen was relatively lower than that of the other sections. Therefore, in order to avoid the failure of the PZT sensors in the experiment, they were embedded near top end of each specimen.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Mass Density, \(\rho\)** & **Pioneelectric Strain** & **Piezoelectric Voltage** & **Relative** & **Piezoelectric Coupling** \\
**Constant, \(\delta_{11}\)** & **Constant, \(\delta_{12}\)** & **Permitivity\(\epsilon_{13}\)\(T_{\delta 6}\)** & **Constant, \(\mathbf{K_{11}}\)** \\ \hline
7960 kg/m\({}^{3}\) & \(345\times 10^{-12}\) m/V & \(9.8\times 10^{-3}\) V/m/N & 3000 & 0.46 & \(6.3\times 10^{12}\) N/m\({}^{2}\) \\ Planar coupling & Piezoelectric strain & Piezoelectric voltage & Relative & Piezoelectric  
Figure 4: Piezoelectric sensor and the drilled and post-sealed bore hole.  
Figure 3: Experimental set up and positions of markers. (**a**) Specimen setup; (**b**) Markers of the optical measuring system; (**c**) Microscope; (**d**) Detail of testing setup.