## 2 Experimental Setup for Cyclic Loading Test
Base on the loading distribution steel beam and steel anchor bolts, the horizontal and vertical loading could be assumed uniformly distribute into the beam of specimens. The load cell equipped on the beam end was used to measure the horizontal loads applied by the actuators. The linear variation displacement transducers (LVDT) were used to measure the top and bottom horizontal displacements of the wall panel and the dial gauge was used to monitor the foundation deformation. The configuration drawing and photo of the test setup for the reversed cyclic loading test are shown in Figure 5. Steel bracing frames were installed on the two sides of the tested specimen to avoid the unexpected torsional motion of the wall specimen. Reversed cyclic loading test was performed with a predetermined increasing drift ratio for each step until the complete failure of the specimen. In specimen RCW1, the foundation and boundary column were damaged during the test because of the low compressive strength of concrete. In such a design, the existing RC frame is much weaker than the retrofitted member. Therefore, the failure occurs at an interface between the existing RC frame and the retrofitted RC wall. In specimen RCW2, the interface between the top beam and the wall panel was damaged first and then the concrete around the top corner of the wall panel was crushed. Finally, the concrete in the top region of the boundary columns was crushed and severely spalled. In this design, the strength of an interface between the existing RC frame and the retrofitted RC wall is insufficient. Therefore, failure also occurs at an interface between the existing RC frame and retrofitted RC wall. Piezoceramic-based sensors (PPTs) were post-embedded at predetermined locations after 28 days of concrete casting of the wall panel. The distributed PPTs, labeled with the capital letters \"S\" and \"A\" in Figures 6 and 7 were used as receivers (sensors) and actuators, respectively. The catalog values of the piezoelectric voltage constants (g\({}_{33}\)) and the piezoelectric strain constant (d\({}_{33}\)) in the polarization direction for the sensors are 250 \(\times\) 10\({}^{-4}\) Vm/N and 43 \(\times\) 10\({}^{-11}\) m/V, respectively; and those for the actuators are 140 \(\times\) 10\({}^{-4}\) Vm/N and 65 \(\times\) 10\({}^{-11}\) m/V, respectively. For the post-embedded transducers in the existing RC structures, the size of the SA adopted in the research [9; 10] is too large for post-embedding them into the RC structures. Therefore, piezoceramic patches that were coated only with a waterproof layer were directly embedded into the structures as sensors and/or actuators for SHM. The transducers are installed by drilling small holes in the wall, top beam and foundation. The depth and diameter of each drilled hole are approximately 8 cm 1.2 cm, respectively. The transducers with a waterproof layer are then placed in the holes, which are refilled with non-shrinking cement mortar. Figure 6 displays the configuration of the installation of the post-embedded transducers. Figure 7 shows the locations of the PPTs in the foundation, wall and foundation. The wave paths for monitoring are also shown in figure. Each specimen has nine PPTs as depicted in Figure 7. Six (S1-S6) are embedded as sensors in the top beam and in the middle-height region of the wall panel. The others (A1-A3) are set in the foundation as actuators. Wave signals that are received from the sensors are used to assess the state and location of damage throughout the wall structure. The adopted piezoceramic-based sensing system has a favorable high-frequency response and provides active sensing. Its high-frequency response property can be used to detect very minor damage and/or small cracks that cannot be identified by visual inspection. In the active sensing, one PPT actuator can send the desired excitation stress waves so that other PPT sensors can receive response signals.