Passive Control of Building Structures Using Double-Skin Facades as Vibration Absorbers

Seismic performance of buildings retrofitted with nonlinear viscous dampers and adjacent reaction towers

“…As in the case of the existing building, all the modes of vibration have been used ( m j =3 n S ) to build the matrices of inherent damping c ( j ) (with j =1,2,3), assuming the same modal viscous damping ratio ζ ( j ) =0.05. It is worth noting here that the coefficients M (0) / M ( j ) =15, J (0) / J ( j ) =800 and K (3) / K (1) =1.5 have been assumed based on preliminary design considerations on the individual reaction towers and the feasibility of the intervention; these values could be potentially subjected to further optimization through appropriate heuristic search methods (eg, genetic algorithms and particle swarm optimization, as in Palmeri et al and Pipitone et al), but this beyond the scope of the present study.…”

Optimal design of double-skin façades as vibration absorbers

“…The effects of the rotational mass in the DSF panel is neglected, meaning that the rotational DoFs can be statically condensed. () Accordingly, the coupled system, that is primary building and DSF panels, has n tot =3 n 0 +( N −1) dynamically significant DoFs (i.e., for each storey, the horizontal translation of the storey mass and of two lamped masses in the panel, plus one DoF for each additional mass at discontinuities between panels). The equations of motion can be written in compact matrix form as …”

“…The DSF mass has been fixed considering a mass ratio μ =0.1. Four different configurations have been studied to analyse all possible combinations of panels covering whole numbers of storeys of the primary structure, that is, (a)a single panel ( N =1) hinged to the ground and connected to the primary structure by one α ‐type and five β ‐type springs; (b)two panels ( N =2), the lowest one hinged to the ground (this is the same configuration analysed in Palmeri et al ()); (c)three panels ( N =3), the lowest one hinged to the ground; and (d)six panels ( N =4), one per storey, the lowest one hinged to the ground. …”

“…The DSF mass has been fixed considering a mass ratio = 0.1. Four different configurations have been studied to analyse all possible combinations of panels covering whole numbers of storeys of the primary structure, that is, (a) a single panel (N = 1) hinged to the ground and connected to the primary structure by one -type and five -type springs; (b) two panels (N = 2), the lowest one hinged to the ground (this is the same configuration analysed in Palmeri et al [22] ); (c) three panels (N = 3), the lowest one hinged to the ground; and (d) six panels (N = 4), one per storey, the lowest one hinged to the ground. For each of the four configurations, the displacement-and acceleration-based objective functions J k proposed in Section 3.1 have been minimised using the PSO algorithm, [28][29][30] considering the 20 earthquake records reported in Table 1; this corresponds to a total number of 4 × 2 × (20 + 1) = 168 optimisation problems.…”

“…[9,16] The performance of DSFs as vibrating masses to control the seismic motion have been investigated by Abtahi et al, [17] who have compared the response of a building structure in three configurations, namely, without DSF and with both fixed and movable DSF, showing that the latter was the most efficient configuration in reducing the structural vibrations.Fu et al [18,19] have investigated five configurations of DSF modelled as TMD, comparing their performance in terms of mean-square interstorey drifts under the earthquake loads. In their studies, the 2-and 10-damper DSF configurations resulted as the best and worst performing systems, respectively, demonstrating the importance of an appropriate design of the DSF, based on structural dynamics considerations.Azad et al [20,21] have analysed the DSF to control wind-induced vibrations by modelling it as a TMD excited by a sinusoidal signal with variable frequency.More recently, Palmeri et al [22] have proposed a preliminary study on the coupled dynamic problem of a DSF attached to a multidegree of freedom shear-type structure excited by seismic ground motions. The DSF has been modelled as a system of 2 independent flexible panels, connected to the main structure by elastic links.…”