Magnetorheological fluid (MRF) and shape memory alloy (SMA) are two smart materials used in many protective systems in civil engineering to mitigate unpredicted hazards. Isolation systems, dampers, and bracing systems are examples of smart protective systems integrated with civil infrastructures, such as building, to enhance their dynamic behaviour. Among them, bracing systems are the most common technique to keep buildings safe and healthy under seismic loads. In this study, both materials are used to develop a new bracing system called the SMA-MRF core-based bracing.

A prototype of the system is fabricated and tested by the loading frame machine to prove the functionality of the system regardless of loading directions. Then, a numerical model of the systems is developed in the Open System for Earthquake Engineering Simulation (OpenSees). This model is implemented in a simplified two-story steel frame and exposed to the simulated ground motions. It is noted that the system improves the structural dynamic behaviour, such as the drift ratio, in the time-domain as well as frequency-domain. A control strategy is applied to the SMA-MRF core bracing systems. It is found that the system enhances the dynamic response with the embedded controller.

The experimental results indicate that pre-straining SMA elements lead to a sharp increase in the energy absorption capacity as well as the recovery ability under short and long-term loadings. It is worth mentioning that the pre-strained SMA maintains the specifications, particularly the recovery capability, rather than conventional SMA under simulated short- and long-term loading.