# A Restoring Force Model for Prefabricated Concrete Shear Walls with Built-In Steel Sections
## 3 Experimental Plan  
Low-cyclic horizontal loading was applied through an MTS electro-hydraulic servo actuator fixed on the reaction wall with a range of \(\pm\)250 mm (\(\pm\)1000 kN). The vertical load was applied through an electro-hydraulic servo jack fixed on a portal reaction frame. A rolling guide rail was set between the portal frame and the loader to reduce the friction so the top of the wall specimen could move freely in the horizontal direction. During the test, the shear wall specimens were placed vertically at the designated position, and the wall footing was fixed on the laboratory floor by ground anchor bolts. A distribution steel beam slightly longer than the wall length was placed on the top of the wall to distribute the vertical load. One end of the actuator was fixed to the steel plate on the reaction wall by high-strength bolts, and the other end applied the load on the shear wall through a pair of steel plates fixed on the top side of the wall. The layout of the tests is shown in Figure 5. The actuator acted on the top side of the wall specimen over an area of 300 mm \(\times\) 120 mm. The actuator was connected with a computer system, and the load and displacement on the top of the wall specimen can be obtained in real-time with the sensors on the actuator and on the top of the wall as well as on both sides of the footing, as shown in Figure 5. Strain gauges were glued on the reinforcing bars and on the outer flanges of the I-shaped steel sections at the bottom section of the wall, as shown in Figures 3 and 4, to measure the strains at those locations. All the strain gauges are placed along the longitudinal direction of the steel section flange or reinforcement bars. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Type** & **Size (mm)** & \begin{tabular}{c} **Yield Strength** \\ **(MPa)** \\ \end{tabular} & \
\begin{tabular}{c} **Ultimate Strength** \\ **(MPa)** \\ \end{tabular} &
\begin{tabular}{c} **Modulus of** \\ **Elasticity (MPa)** \\ \end{tabular} \\ \hline Steel bars & 6.5 (diameter) & 363 & 454 & \(2.12\times 10^{5}\) \\ \hline Steel sections & \(100\times 68\times 4.5\times 7.6\) & 278 & 382 & \(1.92\times 10^{5}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Property parameters of the steel bars and steel sections. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Wall** & **Wall Size (mm)** & **Horizontal Rebar** & **Vertical Rebar** & **Stirups** & **Axial Compression Ratio \({}^{*}\)** \\
**Code** & & & & & \\ \hline XZW1 & 2000 \(\times\) 960 \(\times\) 120 & \(\Phi\)6.5\(\Phi\)100/200 \({}^{1}\) & \(\Phi\)6.5\(\Phi\)100 & \(\Phi\)6.5\(\Phi\)100/200 \({}^{1}\) & 0.05 \\ XZW2 & 2000 \(\times\) 960 \(\times\) 120 & \(\Phi\)6.5\(\Phi\)100/200 \({}^{1}\) & \(\Phi\)6.5\(\Phi\)100 & \(\Phi\)6.5\(\Phi\)100/200 \({}^{1}\) & 0.15 \\ XZW3 & 2000 \(\times\) 960 \(\times\) 120 & \(\Phi\)6.5\(\Phi\)100/200 \({}^{2}\) & \(\Phi\)6.5\(\Phi\)100 & \(\Phi\)6.5\(\Phi\)100/200 \({}^{2}\) & 0.05 \\ XZW4 & 2000 \(\times\) 960 \(\times\) 120 & \(\Phi\)6.5\(\Phi\)100/200 \({}^{2}\) & \(\Phi\)6.5\(\Phi\)100 & \(\Phi\)6.5\(\Phi\)100/200 \({}^{2}\) & 0.15 \\ \hline \hline \end{tabular}  
* 1. spaced @100 mm on the top 300 mm of the wall and in the connection at the bottom of the wall; 2. Spaced @100 mm on the top 300 mm of the wall and in the connection 400 mm above the bottom of the wall (\(\Phi\) is the diameter of bars, \(\emptyset\) is the center-to-center distance of bars.)
* Axial compression ratio: the ratio of the vertical pressure applied on the wall to the compressive strength of the wall.  
\end{table} 
Table 2: Reinforcements of the walls. A vertical pressure was applied on top of the specimen according to the preset axial pressure ratio to evaluate the effect of the vertical pressure. After the vertical load stabilized, low cyclic horizontal loading was applied. A vertical pressure of 5% of the compressive strength of the wall was applied to XZW 1 and 3 while a vertical pressure of 15% of the compressive strength was applied to XZW 2 and 4.