Three-dimensional seismic response analysis of connected structures with damping layers

A ridge-isolated tuned mass damper for seismic rehabilitation of a 3D structure under bidirectional earthquakes.

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.

Seismic Performance of a Frame–Core Tube Building with Nonlinear Viscous Damper-Equipped Coupling Beams

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.

Seismic Performance Evaluation of a Building Incorporating Different Lateral Load Resisting Systems

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.

Seismic response mitigation of wind turbine towers using a nonlinear magnetic damper

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.

Comparative performance of isolated and fixed-base reinforced concrete structures

Comparative Evaluation of Seismic Resistance, Damping, and Base Isolation under Earthquake Loading Using 3D-Printed Building Models

This study investigates the effectiveness of different seismic design strategies in improving the earthquake resilience of buildings. Motivated by the 2011 Tohoku earthquake in Japan, the research focuses on three major seismic systems: seismic resistance, seismic damping, and seismic base isolation. Seismic resistance enhances structural strength to withstand forces, seismic damping dissipates energy through mechanisms such as dampers, and base isolation reduces energy transfer by separating the building from the ground. An experimental approach was used involving 3D-printed building models equipped with each system. Measurements of wave amplitude and displacement were recorded to assess performance under simulated seismic activity. Results indicated that seismic damping was most effective in reducing wave amplitude, while base isolation minimized displacement. Seismic resistance was the most economical but least effective in mitigating energy. The findings highlight the importance of selecting seismic designs based on building context while balancing safety and cost. Limitations include the small experimental scale and simplified simulation conditions, suggesting the need for further research under more realistic scenarios.