## 2 Experimental Program
### Specim Grouping and Design
#### 2.1.3 Lcess Design  
Based on previous research results [2], the LOSS design included structural and connection components. For the structural design, the pre-assembly form and segment dimensions were determined. The sleeve ring comprised three standard segments, one adjusting segment, and a setting rabbet between them. To improve the strength and durability of the LOSS as the structural reinforcement for the concrete segment, we set the double-layer  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Group**} & \multirow{2}{*}{**Specimen**} & \multicolumn{3}{c}{**Core Pier Column**} & \multicolumn{3}{c}{**SSAWC**} & \multicolumn{3}{c}{**LCSS**} \\ \cline{3-10}  & & \(\mathbf{D\times H}\) & **LDR** & **Initial Damage** & **Thickness** & **Self-Stress** & **Reinforcement** & **Thickness** & **Reinforcement** \\  & & & **(mm)** & **(mm)** & **(mm)** & **(MPa)** & **Ratio (\%)** & **(mm)** & **Ratio (\%)** \\ \hline \multirow{3}{*}{G0} & UP-1 & 250 \(\times\) 1000 & 4 & Intact & & & & & \\  & UP-2 & 250 \(\times\) 1500 & 6 & Intact & & & & & \\  & UP-3 & 250 \(\times\) 2000 & 8 & Intact & & & & & \\ \hline G1 & RP-0 & 250 \(\times\) 1000 & 4 & Intact & 40 & 0 & 0.28 & 40 & 0.5 \\ \hline \multirow{3}{*}{G2} & RP-1 & 250 \(\times\) 1000 & 4 & Intact & 40 & 1.6 & 0.28 & 40 & 0.5 \\  & RP-2 & 250 \(\times\) 1000 & 4 & Intact & 40 & 1.6 & 0.28 & 40 & 0.25 \\  & RP-3 & 250 \(\times\) 1000 & 4 & Dumaged & 40 & 1.6 & 0.28 & 40 & 0.5 \\  & RP-4 & 250 \(\times\) 1500 & 6 & Intact & 40 & 1.6 & 0.28 & 40 & 0.5 \\  & RP-5 & 250 \(\times\) 2000 & 8 & Intact & 40 & 1.6 & 0.28 & 40 & 0.5 \\ \hline \hline \end{tabular} Note: (a) UP and RP represent the unreinforced and reinforced specimens, respectively. (b) D, H, and LDR represent the diameter, height, and length-diameter ratio, respectively, of the unreinforced core pier column. (c) The reinforcement ratio of the LCSS can be weakened by reducing the number of welded steel wire mesh layers in the segment. Reinforcement ratios of 0.25% and 0.5% represent the setting of one and two layers of wire mesh in the segment sleeve, respectively.  
\end{table}
Table 1: Main design parameters and grouping of the specimens.  
Figure 2: Dimensions and reinforcement layout of the core pier columns (unit: mm). (a) Front view; (b) Side view; (c) 1–1 profile; (d) 2–2 profile.  
-welded steel wire mesh with a 1.2 mm diameter and mesh size of 25 mm \(\times\) 25 mm in the segment [2]; the concrete strength grade was C40. The lengths of the upper and lower meshes in the standard segments were 375 and 320 mm, respectively. The lengths of the upper and lower meshes in the adjusted segments were 125 and 106 mm, respectively. The width of the wire mesh was 170 mm. The segments' inner and outer diameters, thickness, and height were 165, 205, 40, and 170 mm, respectively. Figure 3 shows the structure of the LCSS.  
For the connection design, the holes were reserved using pre-embedded PVC pipes to fix the bolts, and curved bolts and triangular blocks were used for the circumferential connection of the segments. Long bolts and nuts were used for the longitudinal connection of the segments by reserving the holes. The diameters of the PVC pipes, circumferential bolts, and longitudinal bolts were 16, 6, and 8 mm, respectively. Three circumferential connections were equally spaced longitudinally around each ring segment, and 10 longitudinal connections were arranged at equal intervals along the circumference. The connections between the segments are shown in Figure 3, while the LCSS and prefabricated models are shown in Figure 4. The material properties of the concrete, welded steel wire mesh, and bolts in the LCSS are presented in Table 3.