VARIABLE ORIFICE DAMPER IMPLEMENTATION FOR SEISMIC SEMI-ACTIVE CONTROL OF CIVIL STRUCTURES

The existing strategies for improving the dynamic response of structures during seismic events can be categorized into passive, active, and semi-active control. Passive strategies provide a redesign of the structural dynamic parameters without employing any real-time control. Active control strategies are more effective than the previous one, but also more expensive. Furthermore, a relevant amount of energy supply is required during seismic events, which is a quite unrealistic scenario. Semi-active control strategies represent a compromise between the two previously mentioned strategies. These latters provide real-time control, less induced costs, and require less power supply. In this study, the behaviour and effectiveness of a semi-active damper have been analyzed. A single degree of freedom (DOF) system has been implemented in the Matlab Simulink environment equipped with a semi-active fluid viscous damper model. Two main control algorithms of the semi-active device have been considered: a proportional-integral-derivative (PID) and a model predictive control (MPC) controller. The control algorithms were designed by linearizing the device constitutive model and implementing their non-linearity through the characteristic equation of the device. Different levels of approximation of the model were considered, in conjunction with different sampling time rates to examine the delay effect of a possible practical implementation of the proposed system.