# Evaluation of Structural Behavior of Hysteretic Steel Dampers under Cyclic Loading
## 2 Experimental Study  
### Design of Specimens  
In this study, relatively simple steel dampers that have excellent energy dissipation capacity were planned. As a result of the tension test, the yield strength of the steel used for the dampers was 245 MPa, the tensile strength was 420 MPa, and the strain at yielding was 0.00147. As shown in Table 1, according to the shape of the damper, two types of specimens were designed: open and closed. Each specimen had four identical steel dampers to avoid eccentric deformation.  
As shown in Figure 1, all the steel dampers were divided into energy dissipation members and shear plates that transferred external shear force. The size of each shear plate was 75 mm \(\times\) 110 mm and the thickness was 20 mm. The shear plates were located on each side, and the distance between them was 90 mm. The steel dampers were designed in opened U- and angled U-shapes and a closed D-shape according to the shape of the energy dissipation parts. The thickness of all dampers was 20 mm, and the width of the member for energy dissipation was planned to be 15 mm. The spacing between the shear plates, the thickness of the dampers, and the width and height of the energy dissipation members were designed in consideration of the strength and deformation capacities of the specimens. The corners of the steel dampers were rounded to prevent stress concentration.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & & & \multicolumn{3}{c}{**Steel Dampers**} & \\ \cline{3-6} \multirow{2}{*}{**Specimens**} & \multirow{2}{*}{**Type**} & \multirow{2}{*}{**Shape**} & \multicolumn{3}{c}{**Energy Dissipation Member**} & \multirow{2}{*}{\begin{tabular}{c} **Number** \\ **of Steel** \\ **Dampers** \\ \end{tabular} } \\  & & & **(mm)** & **(mm)** & **(mm)** & **(mm)** & **(mm)** \\ \hline SD1 & \multirow{2}{*}{\begin{tabular}{c} Opened \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} U-shape \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} B=15 \\ H=30 \\ B=15 \\ H=45 \\ B=15 \\ H=30 \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} R=60 \\ d\({}_{1}\)=45 \\ B=15 \\ H=30 \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} N/A \\ H=45 \\ B=15 \\ H=30 \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} 20 \\ B=15 \\ H=45 \\ B=45 \\ \end{tabular} } \\ \hline SD means steel damper; B and H are the width and height of member, respectively; d\({}_{\text{o}}\) and d\({}_{\text{i}}\) are the outer and inner diameters, respectively. & & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Details of specimens.  
As shown in Figure 1, the U-shaped energy dissipation part of the SD1 damper specimen had a height of 90 mm. The energy dissipation part had two vertical members, each with a height of 30 mm, and a semicircular member with an inner diameter of 90 mm. SD2 consisted of horizontal and vertical steel members in order to observe the change in structural behavior when the connecting member was changed from semicircular to horizontal. The vertical members were planned to be 45 mm high, and other details of the specimen were the same as for SD1. The SD3 damper had an additional horizontal member added to the lower part of SD1 to increase the load resisting capacity. The lower horizontal member had a cross-sectional area of 15 mm \(\times\) 20 mm. The dimensions of the vertical and connecting members of SD3 were the same as those of SD1.