Search Results (198)

In this paper, a viscoelastic (VE) tuned inerter damper (TID) that replaces conventional stiffness and damping elements with a cost-effective VE element is proposed to achieve a target-based improvement of seismically protected buildings. The semi-analytical solution of the optimal tuning frequency ratio of the VE TID is presented based on a two-degree-of-freedom (2-DOF) system, accounting for inherent structural damping disturbances, and then is extended to a MDOF system via an effective mass ratio. The accuracy of the semi-analytical solution is validated by comparing the numerical solution. Finally, numerical analyses on a viscoelastically damped building and a base-isolated building with optimally designed VE TIDs under historical earthquakes are performed. The numerical results validate the target-based improvement capability of the VE TID with a modest mass ratio in avoiding large strokes or deformation of existing dampers and isolators, and further reducing the specific mode vibration. Full article

The ultimate goal of research on seismic mitigation technologies is engineering application. However, current studies primarily focus on the application of dampers in planar structures, while actual engineering structures are three-dimensional (3D) in nature. A type of damper, making up tuned mass dampers (TMDs) and inerters, has excellent vibration mitigation performance and needs brackets to connect to structures. In this work, a coupled dynamic model of an energy dissipation system (EDS) comprising a TMD, an inerter, a bracket, and a 3D building structure is presented, along with analytical solutions for stochastic seismic responses. The main work is as follows. Firstly, based on D’Alembert’s dynamics principle, the seismic dynamic equations of an EDS considering a realistic damper and a 3D structure are formulated. The general dynamic equations governing the bidirectional horizontal motion of the EDS are further derived using the dynamic finite element technique. Secondly, analytical expressions for spectral moments and variances of seismic responses are obtained. Finally, four numerical examples are presented to investigate the following: (1) verification of the proposed response solutions, showing that the calculation time of the proposed method is approximately 1/500 of that of the traditional method; (2) examination of spatial effects in 3D structures under unidirectional excitation, revealing that structural seismic responses in the direction along the earthquake ground motion is approximately 10⁴ times that in the direction perpendicular to the ground motion; (3) investigation of the spatial dynamic characteristics of a 3D structure subjected to unidirectional seismic excitation, showing that the bracket parameters significantly affect the damping effects on an EDS; and (4) application of the optimization method for the damper’s parameters that considers system dynamic reliability and different weights of the damper’s parameters as constraints, indicating that the most economical damping parameters can achieve a reduction in displacement spectral moments by 30–50%. The proposed response solutions and parameter optimization technique provide an effective approach for evaluating stochastic seismic responses and optimizing damper parameters in large-scale and complex structures. Full article

Ensuring the safety of large spherical water storage tanks in seismic environments is critical. Therefore, this study proposed a vibration control device applicable to general spherical water tanks. By utilizing the upper interior space of a spherical tank, a novel tuned mass damper (TMD) system composed of a mass block and four elastic springs was proposed. To enable practical implementation, the vibration control mechanism and tuning principle of the proposed TMD were examined. Subsequently, an experimental setup, including the spherical water tank and the TMD, was developed. Subsequently, shaking experiments were conducted using two types of spherical tanks with different leg stiffness values under various seismic waves and excitation directions. Shaking tests using actual El Centro NS and Taft NW earthquake waves demonstrated vibration reduction effects of 34.87% and 43.38%, respectively. Additional shaking experiments were conducted under challenging conditions, where the natural frequency of the spherical tank was adjusted to align closely with the dominant frequency of the earthquake waves, yielding vibration reduction effects of 18.74% and 22.42%, respectively. To investigate the influence of the excitation direction on the vibration control performance, shaking tests were conducted at 15-degree intervals. These experiments confirmed that an average vibration reduction of more than 15% was achieved, thereby verifying the validity and practicality of the proposed TMD vibration control system for spherical water tanks. Full article

The dynamic control of vibrations in skyscrapers is a critical consideration in sustainable building design, particularly in response to environmental excitations such as wind impact or seismic activity. Effective vibration neutralisation plays a crucial role in providing the safety of high-rise buildings. This research introduces an innovative concept for an active vibration damper that operates based on fluid dynamic transport to adaptively alter a skyscraper’s natural frequency, thereby counteracting resonant vibrations. A distinctive feature of this system is an adjustable-length cable mechanism, allowing for the dynamic modification of the pendulum’s effective length in real time. The structure, based on cable length adjustment, enables the PTMD to precisely tune its natural frequency to variable excitation conditions, thereby improving damping during transient or resonance phenomena of the building’s dynamic behaviour. A comprehensive mathematical model based on Lagrangian mechanics outlines the governing equations for this system, capturing the interactions between pendulum motion, fluid flow, and the damping forces necessary to maintain stability. Simulation analyses examine the role of initial excitation frequency and variable damping coefficients, revealing critical insights into optimal damper performance under varied structural conditions. The findings indicate that the proposed pendulum damper effectively mitigates resonance risks, paving the way for sustainable skyscraper design through enhanced structural adaptability and resilience. This adaptive PTMD, featuring an adjustable-length cable, provides a solution for creating safe and energy-efficient skyscraper designs, aligning with sustainable architectural practices and advancing future trends in vibration management technology. The study presented in this article supports the development of modern skyscraper design, with a focus on dynamic vibration control for sustainability and structural safety. It combines advanced numerical modelling, data-driven control algorithms, and experimental validation. From a sustainability perspective, the proposed PTMD system reduces the need for oversized structural components by providing adaptive, efficient damping, thereby lowering material consumption and embedded carbon. Through dynamically retuning structural stiffness and mass, the proposed PTMD enhances resilience and energy efficiency in skyscrapers, lowers lifetime energy use associated with passive damping devices, and enhances occupant comfort. This aligns with global sustainability objectives and new-generation building standards. Full article

High-rise industrial buildings are particularly susceptible to vibration-induced comfort issues, which can negatively impact both the health and productivity of workers and office staff. Unlike most existing studies that focus on local structural components, this study proposes and validates a wave propagation analysis (WPA) method to predict peak accelerations of the floor caused by excitations located on different floors. The method is validated through on-site vibration tests conducted on a high-rise industrial building with shared factory and office space. A simplified regression-based propagation equation is further developed to facilitate practical design applications. The regression parameters are fitted using theoretical calculation results, enabling rapid prediction of peak acceleration responses on the same or different floors. To enhance vibration control, tuned mass dampers (TMDs) are installed on selected floors, and additional tests are conducted with the TMDs activated. An insertion loss-based correction is introduced into the WPA framework to account for the TMD’s frequency-dependent attenuation effects. The extended method supports both accurate prediction of vibration reduction and optimisation of TMD placement across multiple floors in high-rise industrial buildings. Full article

This study addresses the dynamic response control of deep-water jacket offshore platforms under typhoon and misaligned wave loads by proposing a Tuned Mass Damper (TMD)-based vibration suppression strategy. Typhoon loading is predicted using the Weather Research and Forecasting (WRF) model to simulate maximum wind speed and direction, a customized exponential wind profile fitted to WRF results, and a spectral model calibrated with field-measured data. Correspondingly, typhoon wave loading is calculated using stochastic wave theory with the Joint North Sea Wave Project (JONSWAP) spectrum. A rigorous Finite Element Model (FEM) incorporating soil–structure interaction (SSI) and water-pile interaction is implemented in the Opensees platform. The SSI is modeled using nonlinear Beam on Nonlinear Winkler Foundation (BNWF) elements (PySimple1, TzSimple1, QzSimple1). Numerical simulations demonstrate that the TMD effectively mitigates dynamic platform responses under aligned typhoon and wave conditions. Specifically, the maximum deck acceleration in the X-direction is reduced by 26.19% and 31.58% under these aligned loads, with a 17.7% peak attenuation in base shear. For misaligned conditions, the TMD exhibits pronounced control over displacements in both X- and Y-directions, achieving reductions of up to 29.4%. Sensitivity studies indicated that the TMD’s effectiveness is more significantly impacted by stiffness detuning than mass detuning. It should be emphasized that the effectiveness verification of linear TMD is limited to the load levels within the design limits; for the load conditions that trigger extreme structural nonlinearity, its performance remains to be studied. This research provides theoretical and practical references for multi-directional coupled vibration control of deep-water jacket platforms in extreme marine environments. Full article

This paper analyzes the performance of the TMD-Inerter for tall building damping. The analysis is performed by simulation to ensure ideal working behaviour of the inerter, i.e., the inerter produces a force in proportion to the relative acceleration of its terminals without any friction of real inerter devices such as fly wheels. For the study, the most realistic TMD-Inerter configuration is considered where the inerter is grounded to the TMD mass and the structural mass next to the TMD mass, i.e., the TMD-Inerter is installed in the top floor room of the structure. Approximate closed-form solutions for the tuning of the TMD-Inerter parameters are derived based on the characteristics of the inerter force. The resulting frequency response functions for different inertance ratios are compared to those of the classical TMD with same mass ratio. The results clearly demonstrate that the TMD-Inerter worsens the tall building damping compared to the classical TMD for the realistic situation that the inerter is grounded to the structural mass next to the TMD. There are two physical reasons why the inerter worsens the efficiency of the TMD. First, the inerter force is per definition in proportion to the relative acceleration of its two terminals, i.e., it is not in proportion to the damper mass (absolute) acceleration whereby it does not increase the damper mass. Second, for harmonic excitation the inerter force characteristics show negative stiffness behaviour which explains why the TMD stiffness must be designed by taking into consideration both the TMD physical mass and the inertance to ensure the correct tuning of the TMD-Inerter natural frequency. Full article

This research work aims to design and develop a dynamic vibration absorber that effectively reduces the vibrations of a flexible structure subjected to external loads. The analysis presented in this paper initially focuses on identifying the resonance frequencies of a typical structural system, which serves as the case study, since these frequencies are critical to dampening due to their potential to cause excessively large vibration amplitudes. Following this, the optimal parameters of the vibration absorber, including the mass, stiffness, and damping characteristics of the proposed design, were determined. Additionally, this paper proposes and examines the use of viscous-type damping, which is achieved through piston–cylinder systems connected to the structural components of the analyzed frame structure. Thus, the main contributions of this work include the analytical dimensioning, the technical design, and the virtual prototyping of a dynamic absorber constructed using a guyed mast structure capable of significantly reducing mechanical vibrations. This design solution ultimately enhances the strength and durability of the frame structure represented in the case study under external excitation, particularly in the worst-case scenario of seismic action. Furthermore, a key aspect of this study is implementing a new numerical procedure for identifying the system equivalent stiffness coefficient based on its mass and modal parameters, which is particularly useful in engineering applications. The numerical experiments conducted in this work support the effectiveness of the proposed design solution, devised specifically for the dynamic vibration absorber developed in this paper. Full article

This study investigates the reliability of tall buildings subjected to dynamic across-wind loading, focusing on the Tuned Mass Damper Fluid Inerter (TMDFI). While existing literature emphasises the effectiveness of TMDFI in mitigating seismic hazards, research on its reliability regarding wind hazards remains limited. A wind-sensitive benchmark 76-storey building is modeled to compare the performance of the TMDFI against a traditional tuned mass damper (TMD) and an uncontrolled structure. A Monte Carlo Simulation (MCS) approach comprising 31,500 simulations is employed to assess reliability under uncertain damping ratios and varying turbulence intensities at reference wind speeds of 20 to 40 m/s. Key performance metrics, including peak acceleration and root mean squared (RMS) displacement responses, are derived through spectral analysis in the frequency domain. Results indicate that the TMDFI offers superior reliability, allowing an additional 6–7 m/s in reference velocity before reaching significant failure at the ISO limit state. Peak acceleration and RMS displacement are reduced by up to 64% to the uncontrolled structure. The TMDFI consistently outperforms both the TMD and uncontrolled configurations across all turbulent cases and wind velocities examined. Full article

The optimum tuning of the natural frequency and damping ratio of TMDs for structural modal parameters and various optimization criteria are well-known from the literature. However, when the eigenfrequency and modal mass of the target structural mode are uncertain due to estimation and measurement errors, significant life loads, temperature, and other time-varying effects, the existing TMD tuning rules are not necessarily optimal. An often-adopted method is to select the TMD damping ratio that is greater than optimal value to make the TMD less sensitive to variations of the target eigenfrequency and uncertainty in the modal mass. This heuristic approach is quantitatively investigated by the presented research. Computations are made for different TMD mass ratios, different uncertainties in target eigenfrequency and modal mass, different levels of increased TMD damping, and assuming harmonic excitation. The results demonstrate that there is no simple rule when increased TMD damping is advantageous. Therefore, beneficial TMD increase factors are given as functions of TMD mass ratio and deviations between actual and nominal modal structural properties. These data can be used by engineers for real TMD projects with uncertain modal parameters. Full article

Timber–concrete composite (TCC) floors are gaining popularity in sustainable construction due to their enhanced stiffness and structural efficiency. However, excessive vibrations, particularly those induced by human activity, pose significant challenges to occupant comfort and structural integrity. This study investigates the application of Tuned Mass Dampers (TMDs) to mitigate vibrations in TCC floors, with a focus on enhancing damping performance through the incorporation of pre-strained Shape Memory Alloys (SMAs) (Kellogg’s Research Labs, New Boston, NH, USA). A novel pre-strained SMA–TMD system was designed and experimentally tested to evaluate its effectiveness in vibration control under various loading conditions. The results demonstrate that pre-straining significantly increases the damping ratio of the SMA–TMD, improving its vibration mitigation capability. Compared to non-pre-strained SMA–TMD, the pre-strained SMA–TMD system exhibited superior adaptability and robustness in reducing floor vibrations, achieving a peak acceleration reduction of up to 49.91%. These findings provide valuable knowledge into the development of advanced damping solutions for timber floors, contributing to the broader application of vibration control strategies in sustainable and high-performance building systems. Full article

This paper investigates the optimal design of base-isolated structures equipped with tuned inerter dampers (TIDs) subjected to various ground motions. The Clough–Penzien model is employed to simulate the power spectrum of three types of ground motions: far-fault, near-fault without pulse subset, and near-fault with pulse subset, with the relevant parameters identified based on actual ground motions. The optimal parameters of the TID for base-isolated structures are determined using the H² optimization criterion to reduce the structural displacement response. The impact of relevant design properties about the optimal parameters is analyzed. The seismic control effectiveness of the TID for 5-storey, 10-storey, and 15-storey base-isolated structures with varying heights is then evaluated through time history analysis, considering far-fault, near-fault without pulse subset, and near-fault with pulse subset ground motions. The main conclusions of this study are as follows: the ground motion type, the natural vibration period of the isolated structure, the damping ratio of the isolated structure and the mass ratio of the TID all affect the optimal parameters and should be analyzed based on specific circumstances. The control effectiveness of the TID on displacement and acceleration response is more pronounced under far-fault ground motion than under near-fault ground motion. The TID equipped in the isolation storey exhibits considerable effectiveness in controlling the seismic response of 5-storey and 10-storey base isolated structures, while it exhibits weaker control over the seismic response of the 15-storey structure. Additionally, while the TID primarily targets displacement response control, it also exhibits substantial control over the absolute acceleration response of the structure. Full article

In the current work, two novel tandem-based tuned mass damper configurations are introduced. These configurations extend the recently proposed tuned tandem mass damper inerter (TTMDI) by replacing the linking dashpot with an inerter (i.e., the inerter-connected TTMDI (ICTTMDI)), and an integrated tuned tandem mass damper inerter (I-TTMDI) by integrating recently proposed tuned tandem mass damper (TTMD) configurations. The control efficiency of the optimally designed dampers for a single-degree-of-freedom (SDOF) system was evaluated in a uniform framework to reveal and compare the performances of the ICTTMDI and I-TTMDI with those of other recently proposed tandem-based configurations. The optimum design of all the studied configurations was determined by the particle swarm optimization (PSO) algorithm. The evaluation of the performances included the effectiveness in the frequency domain and that of the norm and maximum reduction in the displacement and absolute acceleration in the time domain under 21 earthquake records with different characteristics. Additionally, the strokes of the dampers, the structure energies, and the power spectral densities (PSDs) of the responses were investigated. The optimum design of the I-TTMDI revealed the best configuration by determining the optimum distributions of the mass and inertance between the tandem mass and inerter links, respectively. The proposed configuration not only demonstrated improved response reduction across the displacement and acceleration measures but also maintained remarkable robustness under 21 earthquake records (far-fault, near-fault forward-directivity, and fling-step records). Furthermore, the advantages of the side inerter distribution were particularly effective at widening the operating frequency band, breaking through the traditional limitations of TMD-based devices. The consistent performances of the newly proposed configurations prove that they can be used to advance the development of more reliable structural control systems. Full article

Originally proposed by the authors, the spring pendulum pounding-tuned mass damper (SPPTMD)—a novel nonlinear damping system comprising a spring pendulum (SP) and motion limiter that dissipates energy through spring resonance amplification and controlled mass-limiter impacts—was theoretically validated for structural vibration control. To experimentally verify its efficacy, a two-story, lightly damped steel frame was subjected to sinusoidal excitation and historical earthquake excitations under both uncontrolled and SPPTMD-controlled conditions. The results demonstrated (1) significant vibration attenuation through SPPTMD implementation and (2) enhanced control effectiveness in soft soil environments compared to stiff soil conditions. Additionally, a numerical model of the SPPTMD–structure system was developed, with computational results showing excellent correlation to experimental data, thereby confirming modeling accuracy. Full article

Tuned Liquid Dampers (TLDs) are dissipative devices that mitigate vibrations through the out-of-phase movement of a fluid, typically water, inside a container relative to a main structure. Water’s low density and viscosity have led to modifications to enhance their effectiveness. Fluid properties, such as density or viscosity, significantly impact their performance by altering mass and damping, respectively. When magnetorheological fluids are employed, magnetic fields can modify the fluid viscosity, affecting the damping. This study experimentally examines the effect of a magnetic field and ambient parameters on the viscosity of different low-cost, custom-prepared magnetic fluids. A tube filled with magnetic liquids into which diverse non-magnetic spheres are dropped was employed, considering on- and off-states of the magnetic field generated by a pair of Helmholtz coils. The impact on the fluid viscosity variation of different measured variables was statistically analyzed. It was found that in all cases, the variations in ambient temperature and relative humidity had no effect on the results. While the magnetic field had a large effect on the viscosity of the magnetic fluid, for the sunflower oil-based fluids, the spheres used or the concentration of iron filings had a greater effect on the viscosity than the presence of the magnetic field. Full article