Modelling of a self-centring damper and its application in structural control

A self-centring SMA damper which shows no residual deformation and moderate energy dissipating capacity is appealing in its potential for seismic design application. The damper examined in this study consists of a re-centring components group and an energy dissipating components group. By using the Bouc–Wen model to describe the energy dissipating group and rigid-elastic model to represent the re-centring group, a new method for the mathematical modelling of the damper has been developed. To validate the feasibility of the proposed SMA damper model, numerical analyses of the damper under sine wave excitations were conducted by programming in the Matlab/Simulink environment. The simulation results of the proposed mathematical model of the SMA damper compare well with those based on a material constitutive model. Furthermore, the SMA damper was applied to two case studies of steel frames under earthquake acceleration excitations and the corresponding time-history analyses were implemented in Matlab/Simulink environment by using the proposed damper model. The results show that the damper is capable of mitigating both floor displacement amplitude and inter-storey drift. For the first floor of the controlled frames in the two case studies, inter-storey drift reductions of 33% and 35%, respectively, were observed in comparison with those of the uncontrolled frames. The results also indicate that the controlled frames vibrate around their initial position, and that there is no residual deformation of the SMA damper.

Research highlights
► A robust method was developed to describe the behaviour of a self-centring damper.
► Two damper functional groups are simulated by the Bouc–Wen and rigid–elastic models.
► This method can be implemented easily by block diagrams in Matlab/Simulink.
► Theoretical analysis of controlled frames under earthquake excitations was conducted.
► The results indicate that the damper can mitigate vibration without residual drift.