This study presents a novel seismic control system, the Mega-Sub Controlled Structure System (MSCSS), to address vibration control challenges in tall and super-tall buildings under intense seismic excitations. The proposed hybrid VD-TFPB-controlled MSCSS integrates Triple Friction Pendulum Bearings (TFPBs) as base isolators with Viscous Dampers (VDs) between the mega frame and the vibration control substructure, enhancing damping and seismic performance. MSCSS without VD and MSCSS with VD models are established and verified using an existing benchmark. The hybrid VD-TFPB-controlled MSCSS is then developed to evaluate its vibration control response while considering soil-structure interaction (SSI). Numerical analyses with earthquake records demonstrate its superior performance compared to MSCSS without and with VD systems. Nonlinear dynamic analyses reveal that the hybrid system significantly improves vibration control. However, under SSI, increased structural flexibility leads to higher frame stress and more plastic hinges, particularly on soft soil, which amplifies vibrations. Despite these challenges, the hybrid VD-TFPB-controlled MSCSS effectively enhances seismic resilience, offering a robust solution for tall buildings.

Determining the optimal damping value of the isolation system in tall structures is challenging as it requires parametric studies and time-consuming nonlinear time-history analyses. Consequently, the influence of different parameters, such as displacement limitation, on the optimal damping of isolators in tall structures remains unclear. This study aims to investigate the optimal damping of isolators in tall structures under two scenarios: a) changing the displacement capacity of the isolators in proportion to the increase of damping (variable gap); b) maintaining a constant displacement capacity of the isolators as the damping increases (constant gap). The study also explores the influence of two additional parameters on the optimal damping of the isolation system, namely the ratio of isolator to superstructure period (TM/TS) and the soil type. The optimal design procedure is illustrated with reference to a case-study 14-story isolated steel structure with an ordinary concentrically braced frames (OCBF) system, isolated with the triple friction pendulum isolator (TFPI) system. The modified endurance time (MET) method is utilized to analyze the seismic response of the case-study structure under increasing levels of earthquake hazard. The analysis reveals that increasing damping in both constant and variable gap modes can effectively reduce the damage level of the structure. However, the effectiveness of increasing damping is limited and influenced by factors such as soil softness and the TM/TS ratio. The optimal damping values are determined based on the desired performance levels for both structural and nonstructural acceleration-sensitive components.

This study investigates the seismic performance of a theoretical hospital building designed as a Fixed-Base (FB) structure according to TSC-2018 (Turkish Seismic Code) and evaluates its behavior under three scenarios: FixedBase (FB), Soil-Structure Interaction (SSI), and Base-Isolated (SSI+ISO). The study employs Nonlinear Time History Analysis (NLTHA) using scaled acceleration records, including one from the 2023 Maras, earthquake. Structural performance is assessed based on maximum roof displacements, interstory drift ratios (IDR), and isolator displacements. Results show that base isolation systems significantly reduce drift demands and roof displacements, keeping the structure within slight damage limits even under extreme seismic loads. In contrast, SSI effects amplify interstory drift demands, increasing the likelihood of exceeding moderate damage thresholds. The analysis highlights the Maras, Education and Research Hospital, which suffered severe damage and became non-operational during the 2023 Kahramanmaras earthquake. This outcome underscores the limitations of fixedbase designs in regions with soft soil conditions and the necessity of incorporating base isolation systems to improve seismic resilience. The findings emphasize the importance of mandatory adoption of base isolation systems in hospital designs, proper consideration of SSI effects, and the retrofitting of existing hospital buildings to meet modern seismic code requirements (TSC-2018) and prevent similar failures in future seismic events.

Purpose Rubber-based isolation systems produce enormous isolator displacement, requiring large seismic gap and causing excessive residual displacement, which can damage the isolator and it has lack of energy dissipation capability. These can be overcome by incorporating shape memory alloy (SMA) with rubber bearing (SMARB). However, studies were conducted ignoring the effect of soil structure interaction (SSI), which significantly alters seismic responses of isolated buildings due to soil flexibility effect. Methods This study aims to assess the optimal seismic performance of a multistoreyed building isolated with SMARB device subjected to recorded earthquakes using particle swarm optimization algorithm to minimize top storey acceleration of building considering the effect of different types of soil, which is modelled using direct method and the soil is considered linear, elastic, massless and homogeneous. The numerical modelling of SMA is done using Graesser-Cozzarelli model and the responses are evaluated by solving dynamic equation of motion of the combined system, which comprises the superstructure, isolator and soil. Results The effect of SSI reduces top storey acceleration and isolator displacement of the isolated building. The top storey acceleration is reduced by 3.1%, 27.8% and 35.8% and isolator displacement is reduced by 15.2%, 24.9% and 32.0% for hard, medium and soft soil, respectively. Negligible residual displacement is obtained for SMARB system considering SSI effects. Conclusion Among the various isolation devices (rubber bearing, lead rubber bearing and SMARB), SMARB performs significantly better and ignoring the effects of soil typology leads to a severe underestimation of the performance of the isolated building.

The Fukushima nuclear incident has heightened global concerns about the safety of nuclear facilities, the imperative to enhance the seismic resilience of nuclear power plants (NPPs) has become a pivotal aspect of nuclear safety. This study introduces an innovative hybrid passive control system that integrates three-dimensional (3D) base isolation technology with periodic isolation walls, aiming to bolster the seismic resilience of NPPs against very rare earthquakes. Furthermore, a complete and viable computational procedure was developed to study the nonlinear soil-structure interaction effects with high-precision wave motion analysis. Finally, the efficacy of the innovative control system to improve the seismic resilience of large-scale nuclear island buildings situated on non-rocky sites was assessed. The findings reveal that the system significantly mitigates the distribution of damage to NPPs during very rare earthquake scenarios. Compared to non-isolated NPP, the adoption of a hybrid passive control system reduces structural damage dissipation energy by 97.73 %. The system augments the effectiveness of 3D base isolation technology in reducing dynamic responses; specifically, the floor response spectra at the top position of the nuclear island building in the X, Y, and Z directions were lowered by 62.33 %, 52.03 %, and 84.12 %, respectively. Moreover, the system considerably reduces the deformation of the 3D isolation bearings. The innovative hybrid passive control system helps to enhance the seismic resilience of NPPs.