Seismic Performance of a Hybrid Semiactive and Passive Control System for a Low-Rise Structure Using Real-Time Hybrid Simulation

Seismic protection of structures is crucial in earthquake engineering, where base isolation is an effective method to reduce seismic vulnerability. However, it often results in large displacements during seismic events. To address this, recent advancements propose the addition of supplemental devices, thus creating hybrid control systems. This study evaluates a hybrid control system combining unbonded fiber-reinforced elastomeric isolators (U-FREIs) with variable orifice dampers (VODs) to enhance the seismic resilience of a low-rise structure, using real-time hybrid simulation (RTHS), which allows the dynamic system of interest to be divided into a numerical substructure and an experimental substructure. In this study, the numerical substructure consists of a 2-degree-of- freedom (DOF) model of a four-column reference structure and two U-FREIs modelled with an extended Bouc-Wen formulation, while the experimental substructure includes two additional U- FREIs along with the VOD. Horizontal and vertical transfer systems (HTS and VTS) were implemented to enable interaction between the substructures. Three seismic events were used to assess the structure’s performance at a peak ground acceleration of 0,1 g (0,981 m/s²). The hybrid control system allows the structure to achieve a reduction of more than 19% in base displacement compared to the simply isolated structure. Additionally, the control system decreases the peak drift by more than 75% when compared to the fixed configuration.