## 6 Conclusions  
The results of a shaking table dynamic experiment conducted on a four-story frame structure equipped with a non-conventional TMD were presented. The control system was realized by isolating the top story mass of the frame structure and connecting it to the substructure with two HDRBs. Through two reference models for comparisons, tests  
Figure 17: NE— Kobe earthquake, configurations compared: FTMD, F4, F3S, (**a**) maximum value of the third floor displacement D\({}_{3}\) versus PGA (**b**) maximum value of the base shear T\({}_{\text{b}}\) versus PGA.  
Figure 18: NE—time history of the base shear for Kobe earthquake at given intensity level, PGA = 0.18 g: (**a**) FTMD vs. F4 configuration, (**b**) FTMD vs. F3S configuration.  
highlighted the effect of floor segmentation and isolation via a non-conventional TMD, without adding structural mass, on an original four-story frame structure, as well as the effect of the insertion of a non-conventional TMD as a general control application on a three-story structure. The main conclusions drawn are the following:  
* From white noise tests, the dynamical characterization of the models tested was conducted by observation of PFRFs. For each configuration, structural identification was carried out. A dynamic behavior for the F4 and F3S configurations emerged that was almost linear. For the FTMD configuration, a softening behavior due to the nonlinearity introduced by the HDRB isolators emerged by increasing the excitation. The first two frequencies decreased with the input intensity, however they maintained a difference between each other, that was almost constant by increasing the excitation. Instead, the first two damping factors showed a rapid exchange between them that was almost constant in the mean value. The high dissipative capabilities induced by the HDRB isolators were highlighted.
* Sine sweep tests confirmed the main resonances observed for the controlled structure as well as the response nonlinearities, highlighted through different amplification values at increasing and decreasing tests.
* The effectiveness of the control strategy was proven from seismic tests, in addition to what was evidenced by white noise and sine sweep tests. Implementing inter-story isolation to realize a non-conventional TMD, all responses were strongly reduced in terms of peaks and RMS values in a wide range of intensities. Adding a non-conventional TMD in an original uncontrolled structure was demonstrated to be effective as well, producing large response reductions in all the ranges of intensities considered.
* With respect to a non-segmented structure, the implementation of inter-story isolation and realization of a non-conventional TMD produced a great attenuation of the dynamic structural response at all the frequencies, proving that it is a smart control strategy useful to enhance structural vibration mitigation.
* With respect to a three-story structure, the introduction of a TMD with a high mass ratio produced its control action mainly around the first mode, with a great attenuation of the dynamic response in a wide range of frequencies centered on the first uncontrolled mode.  
Conceptualization, M.B. and M.D.A.; methodology, M.D.A.; software, M.B.; validation, M.B. and M.D.A.; formal analysis, M.D.A.; investigation, M.B. and M.D.A.; resources, M.D.A.; data curation, M.B.; writing--original draft preparation, M.B. and M.D.A.; writing--review and editing, M.B. and M.D.A.; visualization, M.B.; supervision, M.D.A.; project administration, M.D.A.; funding acquisition, M.D.A. All authors have read and agreed to the published version of the manuscript.  
This research received funding from Progetto Sapienza protocol number N. RP1181643697C751.  
Not applicable.  
The authors would like to acknowledge the students of the course \"Dynamics of Structures\", held by Professor [PERSON], for their active participation in the experimental activities.  
The authors declare no conflict of interest.