Wind turbines in seismically active regions are increasingly vulnerable to earthquake-induced vibrations due to their growing height and flexibility. Effective vibration control is therefore essential to ensure structural safety and operational reliability. This study examines the performance of a novel compact nonlinear magnetic damper with non-contact restoring and damping force generation in mitigating the seismic response of wind turbine towers. The tower is modeled through a three-degree-of-freedom modal representation, corresponding to the first three fore–aft mode shapes obtained from a finite element–based modal analysis. A synthetic acceleration record was then developed by averaging the frequency content of five well-known earthquakes to represent their dynamic characteristics, providing a comprehensive excitation spectrum for evaluation. The damper parameters were optimized using a Bayesian optimization framework, with the root-mean-square of tower-top displacement adopted as the objective function. The optimized configuration was subsequently assessed under each individual earthquake record to evaluate its robustness. Results show that the proposed damper, together with the optimization scheme, achieves 36–65% reductions in RMS tower-top displacement and maintains consistent performance across different ground motions. The findings demonstrate the effectiveness and adaptability of the magnetic damper in enhancing the seismic resilience of wind turbine structures and provide a promising direction for integrating smart damping technologies into renewable energy systems.
Nonlinear velocity dampers (NVDs) embedded in coupling beams may enhance the seismic performance of frame–core tube structures by dissipating energy and limiting structural damage. This study evaluates the seismic performance of a 20-story reinforced concrete (RC) frame–core tube building incorporating NVD-equipped coupling beams. Parametric studies are conducted at the frequent earthquake (FE) level, and nonlinear time-history analyses are performed at the design-basis earthquake (DBE) and rare earthquake (RE) levels. The results show that wall-pier flexure is the primary contributor to damper deformation, and mid-span placement is found to be relatively favorable. The optimal damping coefficient varies with the engineering demand parameters, whether base shear, drift, or additional damping, indicating that damping coefficient should be chosen based on a balanced consideration. For the N. Palm Springs ground-motion record considered in the damage assessment, the NVD-equipped models exhibit less flexural damage than the reference model for varying damping coefficients at both DBE and RE levels. These findings provide case-specific design guidance for applying NVD-equipped coupling beams in comparable RC frame–core tube buildings.
Shen Liu, Bo Li, Hui Wang et al.· Buildings· 0 citations
Long-span bridges are highly susceptible to excessive vibrations in multiple directions induced by wind and earthquakes. Conventionally, vibration control systems are designed separately to addressing wind-induced and seismic responses. This study explores the dual mitigation of these dynamic responses in long-span bridges using damped outriggers (DOs) with nonlinear viscous dampers (NVDs). The DO system consists of outriggers installed on the bridge girder and longitudinal dampers connecting the lower end of the outrigger and a bridge tower or pier. This configuration provides rotational damping to mitigate vertical vibrations and longitudinal damping to suppress the longitudinal response of the girder simultaneously. A comprehensive study has been conducted to design the parameters for DOs of long-span bridges, including the evaluation of external excitations [vortex-induced forces (VIFs) and seismic loads], a corrected modal truncation method for dynamic modeling, and a multiobjective genetic algorithm (MOGA) for optimal parameter design. The framework is validated through numerical application to the Xihoumen Bridge, serving as a representative case. The results demonstrate that DOs installed on the two towers can completely mitigate VIVs across seven modes. In addition, single DO arrangement with independently designed parameters can reduce the longitudinal displacement of the bridge under earthquakes from 18 to 5 cm. Furthermore, MOGA is adopted for optimal design of DOs for dual mitigation, resulting in an optimal system comprising three DOs located at the towers and the north end of the girder. The NVDs in the DOs are designed with an exponent of 0.7 and a viscous coefficient of approximately
10,000
kN
·
(
s
/
m
)
0.7
, while the outrigger length is kept no larger than 18 m. The performance of the optimized DOs is found to be comparable to that of systems designed separately for wind-induced or seismic responses. The proposed methodology provides a generalized and transferable design framework for integrated wind and seismic vibration mitigation in long-span suspension or cable-stayed bridges.
Zhanhang Liu, Lin Chen, Limin Sun et al.· Journal of Structural Engine...· 0 citations
Earthquakes produce significant lateral forces on structures, which may lead to excessive displacement, structural
instability, and collapse if proper seismic resistant measures are not adopted. The present study focuses on the comparative
seismic performance evaluation of a G+11 reinforced cement concrete (RCC) building incorporated with different vibration
control system using ETABS 20. The building was analyzed for Seismic Zone V using the Response Spectrum Analysis (RSA)
method in accordance with the provisions of IS 1893 (Part 1): 2016. Six structural models were considered in the study, namely
bare frame structure, fluid viscous damper model, friction damper model, X-bracing model, shear wall model, and lead rubber
bearing (LRB) base isolated model. The seismic performance of each model was evaluated based on parameters such as
maximum storey displacement, storey drift and storey shear. The results obtained from the analysis indicate that the Shear Wall
model provides the most effective reduction in displacement and drift due to its Enhanced stiffness, although the shear wall and
bracing systems significantly improve structural stiffness but attract higher seismic forces hence greater base shear than bare
frame model. The fluid viscous damper and friction damper showed overall good seismic performance by reducing the overall
displacement, drift and storey shear without attracting higher seismic forces. The base isolated model increases the displacement
due to increased flexibility in the structure but reduces drift and force transmission into the structure. The study concludes that
vibration control systems considerably enhance the seismic performance of RCC structures and assist in improving structural
safety in earthquake-prone regions.
Utkarsh Mishra, Rakesh Grover· International Journal for Re...· 0 citations
Efficient and practical seismic control of structures-particularly through isolation systems-remains a significant challenge due to high implementation costs and construction complexity. Moreover, their application in retrofitting existing structures often requires extensive modifications.To address these challenges, this study proposes a novel and cost-effective seismic control system, termed the Ridge-Isolated Tuned Mass Damper (RITMD), which integrates the advantages of tuned mass damping and seismic isolation. A reduced-order two-degree-of-freedom (2DOF) model is developed to capture the coupled dynamic behavior of the primary structure and the RITMD system. An optimization framework based on the Particle Swarm Optimization (PSO) algorithm is employed to determine the optimal tuning parameters. Subsequently, closed-form design expressions are obtained using nonlinear regression analysis to facilitate practical engineering applications .The proposed approach is further extended to three-dimensional structural systems, and its performance is evaluated through nonlinear time-history analyses under bidirectional earthquake excitations. The results demonstrate that the RITMD system significantly reduces structural responses, including displacements, accelerations, inter-story drifts, torsional demands, and their corresponding root-mean-square (RMS) values.Overall, the proposed system provides an efficient, practical, and versatile solution for enhancing the seismic performance of both new and existing structures.
This study investigates the seismic behaviour of a 10-storey shear-type building subjected to eleven near-field earthquake records while explicitly accounting for nonlinear soil-structure interaction (SSI). To improve seismic performance, a novel multiple active friction-tuned mass damper (MAFTMD) framework is proposed by integrating multiple friction-tuned mass dampers (MFTMDs) with an enhanced integral-derivative tilted (I-DT) control strategy. The nonlinear behaviour of the supporting soil is represented using the Hardin-Drnevich model, enabling strain-dependent stiffness degradation and damping effects to be captured under stiff, soft, and very soft soil conditions. The parameters of the MTMD and MFTMD configurations, along with the gains of the enhanced I-DT controller implemented in the MAFTMD system, are optimized using a multi-objective thermal exchange optimization (MOTEO) algorithm. The optimization simultaneously minimizes peak storey displacement and acceleration while satisfying inter-storey drift ratio constraints. The results demonstrate that incorporating friction mechanisms significantly enhances energy dissipation and structural response mitigation as compared to conventional MTMD systems. Furthermore, the proposed MAFTMD framework provides the most stable and effective overall performance under varying near-field earthquake characteristics and nonlinear soil conditions. The study also shows that nonlinear SSI strongly affects the performance and optimization of structural control systems. Overall, the proposed framework combines friction-based damping, active control, and nonlinear soil modelling to improve the seismic performance of mid-rise buildings under near-field earthquakes.
Morteza Akbari, M. Seifi, T. Falborski et al.· Archives of Civil and Mechan...· 0 citations
To enhance the seismic damping effect of connected structures under intense seismic activities, this study introduces a novel control system for connected structures. This system strategically places the damping layers at different locations within the main towers to mitigate the violent system response of the connected structure during rare earthquakes. The double-sided damping structure mainly involves arranging damping layers in the towers on both sides of the connected structure. The damping layers use lead-core isolation bearings (LRB), which fully combines the concepts of damping and isolation. It applies isolation technology to the damping system of high-rise structures, and can effectively solve the technical problem of overturning when isolation technology is applied to high-rise buildings in engineering experiments. The structure is modeled using ABAQUS. Models for both single-sided and double-sided damping structures are established and subsequently compared with the seismic resistance structure. This comparison is conducted to analyze the time-history response of layer shear, base reaction force, top-layer acceleration, and interstory drift of various structural models under rare earthquakes. Additionally, shear-drift hysteresis curves of the damping layer are constructed to evaluate the energy dissipation rate of the structure’ s damping layer using an energy analysis method. The results show that both damping structures exhibit superior energy dissipation and damping effects. However, the introduction of an additional damping layer in the double-sided damping structure results in a more obvious damping effect and a higher energy dissipation rate. The risk of overturning due to excessive bending deformation of the superstructure is mitigated by designing the location of the damping layer. However, the control effect of both damping structures on vertical earthquakes is not obvious, and further research is needed.