## 6 Experimental Validation of the Vibration-Suppression System (VSS)  
The efficacy of the vibration-suppression system was proven by means of true-scale experimental tests that were carried out at the structural dynamics laboratories of the ENEA Casaccia Research Center (Rome, Italy) [32]. Figure 40: Seismic response, interstory speed at the 5 th floor (\(\Delta v_{y5}=v_{y5}-v_{y4}\)). \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Story (j) \(\rightarrow\)**} & \multicolumn{1}{c}{**1**} & \multicolumn{1}{c}{**2**} & \multicolumn{1}{c}{**3**} & \multicolumn{1}{c}{**4**} & \multicolumn{1}{c}{**5**} \\ \hline  & \multirow{3}{*}{\(\Delta\mathbf{y_{j,\min}}\)} & **(m/s2)** & \(-0.6466\) & \(-0.9931\) & \(-0.9402\) & \(-0.9203\) & \(-1.3862\) \\ \cline{2-8}  & & \(\Delta\mathbf{y_{j,\max}}\) & **(m/s2)** & \(0.5085\) & \(0.8558\) & \(0.9923\) & \(0.9652\) & \(1.3080\) \\ \cline{2-8}  & & \(\Delta\mathbf{y_{j,\min}}\) & **(m/s2)** & \(-0.6466\) & \(-0.4042\) & \(-0.2608\) & \(-0.1716\) & \(-0.0954\) \\ \cline{2-8}  & & \(\Delta\mathbf{y_{j,\max}}\) & **(m/s2)** & \(0.5085\) & \(0.3706\) & \(0.2573\) & \(0.1756\) & \(0.0989\) \\ \cline{2-8}  & & \(\Delta\mathbf{V_{\min}}\) & **(m/s)** & \(-0.0169\) & \(-0.0147\) & \(-0.0105\) & \(-0.0072\) & \(-0.0041\) \\ \cline{2-8}  & & \(\Delta\mathbf{V_{\max}}\) & **(m/s)** & \(0.0155\) & \(0.0136\) & \(0.0096\) & \(0.0066\) & \(0.0037\) \\ \hline  & \multirow{3}{*}{\(\Delta\mathbf{y^{\prime}_{j,\min}}\)} & **(m/s2)** & \(-1.8519\) & \(-3.3017\) & \(-1.8979\) & \(-1.8335\) & \(-3.9358\) \\ \cline{2-8}  & & \(\Delta\mathbf{y^{\prime}_{j,\max}}\) & **(m/s2)** & \(2.1315\) & \(2.9111\) & \(1.9864\) & \(1.9148\) & \(3.8772\) \\ \cline{2-8}  & & \(\Delta\Delta^{\prime}\mathbf{y_{j,\min}}\) & **(m/s2)** & \(-1.8519\) & \(-1.865\) & \(-2.6038\) & \(-3.1147\) & \(-3.1007\) \\ \cline{2-8}  & & \(\Delta\mathbf{a^{\prime}_{j,\max}}\) & **(m/s2)** & \(2.1315\) & \(1.6767\) & \(2.0622\) & \(3.0768\) & \(2.5508\) \\ \cline{2-8}  & & \(\Delta\mathbf{V^{\prime}_{\min}}\) & **(m/s)** & \(-0.0661\) & \(-0.0484\) & \(-0.0491\) & \(-0.105\) & \(-0.0947\) \\ \cline{2-8}  & & \(\Delta\mathbf{V^{\prime}_{\max}}\) & **(m/s)** & \(0.0564\) & \(0.0375\) & \(0.0695\) & \(0.1005\) & \(0.0724\) \\ \hline  & \multirow{3}{*}{\(\Delta\mathbf{y^{\prime}_{j,\min}}-\Delta\mathbf{y_{j,\min}}\)} & \multirow{3}{*}{\(65.08\%\)} & \multirow{3}{*}{\(69.92\%\)} & \multirow{3}{*}{\(50.46\%\)} & \multirow{3}{*}{\(49.81\%\)} & \multirow{3}{*}{\(64.78\%\)} \\ \cline{2-8}  & & & & & & & \\ \cline{2-8}  & & \(\frac{\Delta\mathbf{y^{\prime}_{j,\max}}-\Delta\mathbf{y_{j,\min}}}{\Delta \mathbf{y^{\prime}_{j,\min}}}\) & \multirow{3}{*}{\(76.14\%\)} &  
The reference structure was installed on a shaking table, which reproduced the acceleration of the earthquake that was considered for the VSS design. Three test cases were addressed:  
Test 1: Earthquake striking the clean structure (intended as the reference structure without MRDs installed);  
Test 2: Earthquake striking the structure with selected MRDs (LORD MRD-1005-3) that were installed and not activated;  
Test 3: Earthquake striking the structure with selected MRDs that were installed and activated by a current of 0.5 A. For each test case, the seismic response of the structure was acquired through five monaxial accelerometers that were installed at the center of each floor and oriented along the direction of the excitation (Figure 41). Two extra-accelerometers were placed at the base and on the top of the structure. The accelerometer at the base measured along the direction of excitation and was used to check the coherence of the ground acceleration with the reference seismic accelerogram. The accelerometer at the top of the structure was oriented perpendicularly to the symmetry plane of the structure and was used to verify the absence of significant out-of-plane accelerations. Siemens LMS SCADAS mobile(r) was used to drive the shaking table and to record the accelerometers' signals.