Control of seismic-excited buildings using active variable stiffness systems

A STFT semiactive controller for base isolated buildings with variable stiffness isolation systems

“…Only in the case of Newhall is the first floor acceleration for the controlled case reduced by nearly 10%. This shows that the STFT controller with smooth stiffness variation does not introduce additional accelerations in the lower stories as compared to on-off stiffness switching algorithms developed by other researchers [19,14]. The force-displacement plots are shown in Fig.…”

“…The control algorithm proposed by Kobori et al [5] is based on estimation of the response in each stiffness state and selection of the state which results in the least response. The controller developed by Yang et al [19] is a sliding mode controller. The resetting algorithms [2,18] are effective primarily due to energy dissipation with constant stiffness.…”

Floor spectra of mixed base isolated structures

“…Much work has been done in the field of semi-active control of structures in general and of base isolated structures in particular. Among other references, Nagarajaiah et al (1993) studied a variable normal force friction device, Yang et al (1996) considered variable stiffness devices, Makris (1997) proposed an electrorheological damper to mitigate effects of near fault pulse-like ground motions, Dyke et al (1998) proposed a phenomelogical model for MR dampers based on the Bouc-Wen hystreresis model, Gavin et al (2003) carried out a parametric study of a 3D base isolated structure, taking into account the effect of possible unequal response times of the adaptive fluid dampers, Wongprasert and Symans (2005) investigated experimentally the response of base-isolated structures equiped with semi-active hydraulic dampers, Narasimhan (2004) and Nagarajaiah and Narasimhan (2007) considered the application of H 2 and H ∞ controlers to variable stiffness and damping SAC devices, Sahasrabudhe and Nagarajaiah (2005) conducted analytical and experimental studies on the efficacy of a bang-bang semi-active controler imitating a sky-hook damper, Chang et al (2008) applied a semi-active control strategy with MR dampers to a 3D benchmark base isolated building. More recently Pozo Montero et al (2009) applied a non-linear velocity based control to a 3D benchmark problem, Zapateiro et al (2009) applied a non-linear adaptive back-stepping to a base isolated structure with MR dampers, Bahar et al (2010) proposed an accurate method for the parameter identification of a Bouc-Wen based model of MR dampers, Ozbulut and Hurlebaus (2010) proposed two fuzy logic controllers for variable friction devices to control the response of base isolated structures.…”

A resetting stiffness dynamic controller and its bench-scale implementation

“…The significance of semi-active controls in structural engineering is well established and demonstrated by the large number of related publications [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Semi-active controllers are low power devices that can continue to operate when power is disrupted under severe earthquake loads and typically do not add energy to the system.…”

“…No intended energy removal from the system is involved. Typically, a bracing system is built within the structure which is engaged or disengaged by a semi-active control to establish a non-resonant condition [11,[14][15][16]. The latter approach is based on controlled energy removal from the system by using electrorheological dampers [18][19][20], magnetorheological dampers [2][3][4], friction control devices [21,22], fluid viscous dampers [23,24], and stiffness resetting [5,13].…”