Protecting buildings from seismic events using stiffness softening MRE isolators
Protecting civil engineering structures from uncontrollable events such as earthquakes while maintaining their structural integrity and serviceability is very important; this chapter describes the performance of a stiffness softening magnetorheological elastomer (MRE) isolator in a scaled three story building. The advantage of the stiffness softening MRE isolator over the traditional stiffness hardening MRE isolator is that its lateral stiffness reduces when earthquake comes by activating the system to the semi-active mode while maintaining hard for the normal operating conditions without any power consumption. In order to evaluate its ability to protect structures from seismic motions, a scaled three story building was designed and built according to the scaling laws, and then four stiffness softening MRE isolator prototypes were fabricated and utilized to isolate the building from the motion induced by a scaled El Centro earthquake. Fuzzy logic was used to output the current signals to the isolators based on the real-time responses of the building floors, and then a simulation was used to evaluate the feasibility of this closed loop control system before carrying out an experimental test. The simulation and experimental results showed that the stiffness softening MRE isolator controlled by fuzzy logic proved to suppress any structural vibration.