This report concerns analytical and experimental investigation of base isolated building with magnetorheological (MR) damper. The aim of this study is to show the effectiveness of this semi-active control method compared to ordinary base isolation technique.
The first chapter of this report covers an overview of the existing methods using passive, active and semi active control approach. In the second and the third chapters an analytical study on ordinary viscous dampers and MR dampers with constant applied current showed their limitations and their dependency on the peak ground velocity and the frequency content of input motion. In these chapters, we also showed that ordinary viscous damper with optimal viscosity shows a better performance for low and medium peak ground velocity earthquakes, compared to MR damper with constant current. In the chapter four, an experimental investigation on mechanical properties of a small scale MR damper is presented. This study leaded to a new mathematical model for the simulation of damping force depending on the velocity and the applied current.
In chapter five, analytical and experimental investigations using Skyhook and Linear Quadratic regulator algorithm (L.Q.R.) are conducted. The obtained results are compared with experimental results using LQR, Skyhook, Fuzzy and feed-forward algorithms. These obtained results showed a good agreement between analytical and experimental analysis. In the other hand, L.Q.R. seems to be more efficient compared to skyhook algorithm which showed a great dependency on frequency content of input motion. The comparison between object and applied force in the MR damper showed also a good agreement confirming the validity of the new mathematical model obtained in chapter four.