## 4 Results and Discussions
### Controller System Behavior Analysis  
In order to assess the controlled system effects on the structural behavior, the input signal and third floor acceleration measurements (output) for two case studies are presented in Figures 5 and 6. The input signal generated artificially through shaking table program. This program generates an acceleration signal having a waveform in which parameters such as strong motion duration, ramp times, number of strong motion peaks, etc. are variables. The signal is generated based on the capability of the shaking table [27]. The signal contains the frequencies with a range of 1.2 to 2.6 Hz. This range of frequency is close to the natural frequency of the system identified by conducting free vibration test. Thus, it will make a greater impact on the building response, which helps to investigate the response of the structure for the critical conditions. The dominant frequency of the input signal was reported as 1.92 Hz (see Figure 5b). Being more specific on the effect of increasing the TMD mass of the response of the structure, Figure 6c presents a meaningful suppress on the response of the structure, i.e., 84% for 2.39 kg, which means that mass is playing important role in vibration mitigation. However, the  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Performance** & \\ \hline Peak Force (N) & 375.0 \\ Continuous Force (N) & 84.1 \\ Peak Power (W) & 2261 \\ Continuous Power (W) & 113 \\ Table travel (cm) & \(\pm\)12.0 \\ Table Operational Bandwidth (Hz) & 20 \\ Table Peak Acceleration (g) & 2.0 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Performance properties of the employed shaking table.  
Figure 5: Excitation dynamic signal: (**a**) time domain signal; and (**b**) frequency domain contents.  
damping effect of the controller system can be ignored where it has a significant effect on suppressing the response.  
From Figures 5 and 6, it can be shown that the maximum response of structure is 0.13, 0.10, and 0.08 g for the uncontrolled, TMD-1.80 and TMD-2.39 controlled systems, respectively. Furthermore, increase the TMD mass is increases the mass and damping of the structure which leads to vibration mitigation by 72% and 84% for the TMD 1.80 and 2.39 kg, as well as, the amplitude of time series response of structure is decreased by 30% and 38%, respectively. This means that the controllers are effectively reducing the response. In addition, the dominant frequency for those cases, i.e., where TMD mass is equal to 1.80 and 2.39 kg, are decreased by 9.4% and 11.8%, respectively. Therefore, it can be concluded that the TMD is efficient controller system in the mitigation of the produced vibration of the structures due to dynamic loads. The mass contribution of the TMD control system to the mitigating the produced vibration of the structure is significant and the system is not properly  
Figure 6: **(a,b)** Structural responses for TMD 1.80 and 2.39 kg of uncontrolled and controlled structure behaviors; and **(c)** frequency contents of output measurements.  
tuned. Nevertheless, the obtained structural response can be used for the identification purposes of this study. The time and frequency delay are observed with increasing the mass of TMD (see Figure 6a,b). The advantages of using TMD for vibration control purposes are presented in [5] where the comparison between this system and other passive controls are well presented.