## 2 Experimental Program and Setup
### Test Setup and Loading Protocol  
To investigate the seismic performance of bridge piers, the reversed cyclic loading experiments were conducted at the Southwest Jiaotong University in Chengdu, China. Figure 3 illustrates the schematic diagram of the test setup in the study. All the bridge piers were subjected to a combination of constant axial loading and reversed cyclic lateral loading [31, 32]. To maintain the constant axial loading applied on the top of the specimen, a hinge bearing, and a roller bearing were installed between the reaction rack and bridge pier. A 3200 kN hydraulic jack was installed between the hinge bearing and roller bearing. The cyclic lateral loading was applied on the loading block using a 1000 kN MTS actuator. The positive and negative loading directions are shown in Figure 3.  
Based on the designed axial loading ratio, the vertical loading was first applied to the top of the loading block. Then, the designated cyclic lateral loading was applied on the right side of the loading  
Figure 3: Schematic diagram of the test setup in the study. \begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline
**Specimen** & \(H\) **(mm)** & \(\Lambda\) & \(\rho_{\text{1}}\) **(\%)** & \(\rho_{\text{so}}\) **(\%)** & \(\rho_{\text{si}}\) **(\%)** & \(h\) **(mm)** & \(n\) \\ \hline PP-ECC-1 & 2100 & 7.0 & 1.51 & 0.79 & 0.79 & 250 & 0.1 \\ PP-ECC-2 & 2100 & 7.0 & 1.51 & 0.79 & 0.79 & 500 & 0.1 \\ PP-ECC-3 & 2100 & 7.0 & 1.51 & 0.79 & 0.79 & 250 & 0.3 \\ PP-ECC-4 & 2100 & 7.0 & 1.51 & 0.79 & 0.79 & 500 & 0.3 \\ PP-ECC-5 & 2100 & 7.0 & 1.51 & 0.79 & 0.46 & 500 & 0.1 \\ PP-ECC-6 & 2100 & 7.0 & 1.51 & 0.79 & 0 & 500 & 0.1 \\ RC-7 & 2100 & 7.0 & 1.51 & 0.79 & 0.79 & 0 & 0.1 \\ RC-8 & 2100 & 7.0 & 1.51 & 0.79 & 0.79 & 0 & 0.3 \\ \hline \hline \end{tabular}  
Notes: \(H\): height of pier; \(\lambda\): shear span ratio; \(\rho_{\text{i}}\): longitudinal reinforcing ratio; \(\rho_{\text{so}}\): volume ratios of transverse reinforcement bars of non-PP-ECC portion; \(\rho_{\text{si}}\): volume ratios of transverse reinforcement bars of PP-ECC portion; \(h\): height of PP-ECC region; \(n\): axial loading ratio.  
\end{table} 
Table 3: Design parameters of specimens. block. Figure 4 depicts the reversed cyclic lateral loading protocol used in the test [33]. The loading protocol consisted of two steps. Step (1): the initial levels were applied under a load-controlled mode. With one cycle for each loading level, the increment of lateral loading was set to 5 kN. Step (2): After the longitudinal reinforcement of the pier yielded, the loading protocol was changed to the displacement-controlled mode. The increment of displacement \(\Delta_{\text{y}}\) was determined as the critical yield displacement in Step (1). The displacement levels were set to \(\Delta_{\text{y}}\), \(2\Delta_{\text{y}}\), \(3\Delta_{\text{y}}\), etc. Each displacement level repeated three times. Finally, the experiment was terminated when the active lateral loading had dropped below 85% of the peak value. Reinforced concrete bridge piers bend and deform under the combined lateral and vertical loadings. The curvature performance is commonly used to evaluate the rotation capacity or the variation of rotation at different heights of the bridge pier. A single or double curvature that strongly depends on the end moments and end forces may be acted in a pier. The curvature of a cross-section can be calculated from the strain on both sides of the member and the distance between two edges. Then, the bending moment-curvature curve of the whole member can be obtained from several sections. Alternatively, the vertical displacements of both sides can also be used to calculate the curvature. As illustrated in Figure 5a, three curvature measurement rods and three pairs of cable-extension transducers were installed at the plastic hinge region. The transducer pairs were 15, 30, and 60 cm from the bottom of the pier, and defined as: (left side) ZL-1, ZL-2, ZL-3 and (right side) BL-1, BL-2, BL-3.