Seismic Response Analysis of a Semi-active-controlled Base ...

806040InitialARXN4SIDDirectMeasuredacceleration [cm/s 2 ]200-20-40-60-80-100132.5 133 133.5 134 134.5 135 135.5 136 136.5time [s]Fig. 11 Comparison of time histories for the main shock 7F EW directionSEMI-ACTIVE SYSTEMThe semi-active system control force is derived by the LQG theory and then divided into four dampingcoefficient gains for the Maxwell damper. Figure 12 shows time history of the damping coefficientcalculated from the record of the control signal during the April 7, 2011 aftershock. As the LQG theoryrelies on structural parameters of the building to be controlled, the results obtained through theprevious identifications are expected to improve significantly the system response. However, at thetime of this study, only performances of the control method using the structural parameters at designstage are evaluated. The simulation results are compared among three control cases: 1) the lowestdamping coefficient is given to the semi-active dampers (passive low), 2) the highest dampingcoefficient is given to them (passive high), and 3) the time history of the damping coefficient shown inFig. 12 is applied to them (semi-active).The results for the aftershock are summarized in Table 6 and Fig. 13. Globally, the semi-activecontrol gives the best performances; however, the difference with the passive control is very small andthus it is expected that the parameters updated in this study will improve the performances of thesemi-active control system.15C semi active[tf/kine]81.7050 52 54 56 58 60 62 64 66 68 70time [s]Fig. 12 Control gain signal1034