# Experimental Investigation on the Mechanical Properties of Curved Metallic Plate Dampers
## 3 Mechanical Properties of Curved Plate Damper
### Loading Device and Test Scheme  
The test was carried out in Civil Test Center of Southeast University (Nanjing, China). The loading equipment was a MTS 50-ton fatigue testing machine. The experiment was divided into four groups with eight specimens, with each group having two identical specimens. In order to connect with the servo actuator, a fixture was designed as shown in Figure 4. The inverted T-split and T-base are equipped with triangular stiffening ribs, and the components of the fixture are connected by the bolts.  
The test was divided into standard loading and fatigue loading. According to the multiple of the yield displacement of the damper (\(\triangle\)), the target displacements of the CSPD-1 specimens were 2 mm  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Specimen** & **Yield** & **Tensile** & **Yield** & **Elongation/\%** \\  & **Strength/MPa** & **Strength/MPa** & **Ratio/\%** & **Elongation/\%** \\ \hline CSPD (curved steel plate dampers)-1 & 249.48 & 375.47 & 66.44 & 35.20 \\ CSPD-2 & 236.64 & 370.03 & 63.95 & 37.71 \\ CSPD-3 & 245.09 & 358.03 & 68.46 & 37.59 \\ CSPD-4 & 253.86 & 372.93 & 68.07 & 33.44 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Mechanical properties of steel.  
Figure 4: Schematic diagram of the fixture (**a**) and photograph (**b**) of the testing device.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Specimen** & **b/mm** & **t/mm** & **R\({}^{\prime}\)/mm** & **Straight Section/mm** \\ \hline CSPD-1 & 105 & 6 & 65 & 70 \\ CSPD-2 & 105 & 10 & 65 & 70 \\ CSPD-3 & 105 & 6 & 43 & 70 \\ CSPD-4 & 85 & 6 & 65 & 70 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Specim sizes.  
(0.5 \(\triangle\)), 4 mm (1 \(\triangle\)), 8 mm (2 \(\triangle\)), 12 mm (3 \(\triangle\)), 16 mm (4 \(\triangle\)), 20 mm (5 \(\triangle\)), 24 mm (6 \(\triangle\)), 28 mm (7 \(\triangle\)), 32 mm (8 \(\triangle\)), 36 mm (9 \(\triangle\)), and 40 mm (10 \(\triangle\)), respectively. According to the multiple of yield displacement, all specimens in this test were loaded in 11 stages. The target displacements of CSPD-2 were 1.2, 2.4, 4.8, 7.2, 9.6, 12, 14.4, 16.8, 19.2, 21.6, and 24 mm, respectively. The target displacements of CSPD-3 were 0.9, 1.8, 3.6, 5.4, 7.2, 9, 10.8, 12.6, 14.4, 16.2, and 18 mm, respectively. The target displacements of CSPD-4 were 2.1, 4.2, 8.4, 12.6, 16.8, 21, 25.2, 29.4, 33.6, 37.8, and 42 mm, and the target displacement circulated three times. For fatigue loading, the Code for Seismic Design of Buildings (GB 50011-2010) stipulates that the energy dissipator should circulate 30 times [13] under the designed displacement, and there should be no obvious low-cycle fatigue phenomenon. The fatigue loading displacements of CSPD-1, CSPD-2, CSPD-3, and CSPD-4 were 40, 24, 18, and 42 mm, respectively.  
During the test, force and displacement data were automatically recorded by the servo actuator. In order to study the mechanical properties of the damper, strain gauges were attached to the damper. The locations of the measuring points are shown in Figure 5. Two strain gauges were attached to each group of specimens at positions 1, 2, and 3.