## 2 Experimental Program
### Speciment Making  
The PSRPC columns were fabricated in a factory prefabricated form, with the factory prefabricated part of the RPC shell being fabricated before the internal concrete was poured. The exact steps of fabrication are as follows. 1. The fabricated H-beam was sandpepered and polished to remove surface impurities, as shown in Figure 2a; \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Batch** & **Specimen** & **Specimen Size** & **RPC Strength** & **Size of Section Steel** & **Eccentricity** & **Steel Ratio (\%)** \\  & **Number** & **(mm \(\times\) mm \(\times\) mm)** & **Grade/MPa** & **Size of Section Steel** & **(Rate) e\({}_{\text{0}}\)/mm** & **Steel Ratio (\%)** \\ \hline  & I-PSRPC-1 & 350 \(\times\) 300 \(\times\) 3000 & 120 & H250 \(\times\) 200 \(\times\) 6 \(\times\) 6 & - & 4.1 \\  & I-PSRPC-2 & 350 \(\times\) 300 \(\times\) 3000 & 150 & H250 \(\times\) 200 \(\times\) 6 \(\times\) 6 & - & 4.1 \\ I & I-PSRPC-3 & 350 \(\times\) 300 \(\times\) 3000 & 180 & H250 \(\times\) 200 \(\times\) 6 \(\times\) 6 & - & 4.1 \\  & I-PSRPC-4 & 350 \(\times\) 300 \(\times\) 3000 & 180 & H250 \(\times\) 200 \(\times\) 8 \(\times\) 6 & - & 4.4 \\  & I-PSRPC-5 & 350 \(\times\) 300 \(\times\) 3000 & 180 & H250 \(\times\) 200 \(\times\) 10 \(\times\) 6 & - & 5.1 \\  & II-PSRPC-1 & 350 \(\times\) 300 \(\times\) 3000 & 180 & H250 \(\times\) 200 \(\times\) 6 \(\times\) 6 & 120 (0.4) & 4.1 \\  & II-PSRPC-2 & 350 \(\times\) 300 \(\times\) 3000 & 180 & H250 \(\times\) 200 \(\times\) 10 \(\times\) 10 & 120 (0.4) & 6.4 \\  & II-PSRPC-3 & 350 \(\times\) 300 \(\times\) 3000 & 180 & H250 \(\times\) 200 \(\times\) 14 \(\times\) 14 & 120 (0.4) & 8.7 \\  & II-PSRPC-4 & 350 \(\times\) 300 \(\times\) 3000 & 180 & H250 \(\times\) 200 \(\times\) 6 \(\times\) 6 & 180 (0.6) & 4.1 \\  & II-PSRPC-5 & 350 \(\times\) 300 \(\times\) 3000 & 180 & H250 \(\times\) 200 \(\times\) 10 \(\times\) 10 & 180 (0.6) & 6.4 \\  & II-PSRPC-6 & 350 \(\times\) 300 \(\times\) 3000 & 180 & H250 \(\times\) 200 \(\times\) 14 \(\times\) 14 & 180 (0.6) & 8.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Main parameters of the specimens. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**RPC Strength** & **\(f_{\text{cu}}\)/MPa** & **\(f_{\text{c}}\)/MPa** & **\(f_{\text{ts}}\)/MPa** & **\(E_{\text{c}}\)/MPa** \\ \hline R120 & 124.3 & 106.5 & 8.0 & 41.6 \\ R150 & 150.6 & 128.3 & 9.0 & 45.6 \\ R180 & 180.3 & 146.5 & 9.6 & 50.3 \\ \hline \hline \end{tabular} Note:\(f_{\text{cu}}\) is the RPC cubic compressive strength,\(f_{\text{c}}\) is the RPC axial compressive strength,\(f_{\text{ts}}\) is the RPC splitting tensile strength and \(E_{\text{c}}\) is the RPC modulus of elasticity.  
\end{table} 
Table 2: Mechanical properties of RPC. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Steel** & **Thickness or** & & & & \\
**Categories** & **Diameter/mm** & **Steel Grade** & **\(f_{\text{y}}\)/MPa** & **\(f_{\text{u}}\)/MPa** & **\(E_{\text{c}}\)/MPa** \\ \hline \hline Hoop reinforcement & 8 & HRB400 & 396.5 & 539.6 & 1.92 \(\times\) 10\({}^{5}\) \\ H-beams & 6 & Q345B & 342 & 513 & 2.06 \(\times\) 10\({}^{5}\) \\ H-beams & 8 & Q345B & 345 & 523 & 2.06 \(\times\) 10\({}^{5}\) \\ H-beams & 10 & Q345B & 352 & 549 & 2.06 \(\times\) 10\({}^{5}\) \\ H-beams & 14 & Q345B & 350 & 565 & 2.08 \(\times\) 10\({}^{5}\) \\ \hline \hline \end{tabular} Note:\(f_{\text{y}}\) is the yield strength of the steel,\(f_{\text{u}}\) is the tensile strength of the steel and \(E_{\text{c}}\) is the modulus of elasticity of the steel.  
\end{table} 
Table 3: Mechanical property index of steel. 2. The bias specimen was welded with 4 steel plates at each end, with H-beam strain gauges, and then corrugated steel plates were welded to the H-beam flange in order to form the external RPC inner membrane;
3. The hoops were placed over the sections and welded to the sections at the four corners in order to form the internal section skeleton, as shown in Figure 2b.