Design Of Tuned Mass Dampers Research Articles

Optimization Study of a Tuned Mass Damper for a Large Monopile Wind Turbine

Passively tuned mass dampers (TMDs) are known to effectively mitigate the vibration of wind turbines. However, existing literature predominantly examines their application in damping vibrations of the tower or platform, overlooking the potential benefits of installing TMDs on the turbine blades themselves. This study investigates the impact of wind and wave loads on TMD damping effectiveness and proposes a comprehensive damping strategy involving TMDs installed in both the nacelle and the blades. The design optimized the mass and stiffness of these TMDs to enhance their performance. Results indicate that, as wind speeds increased from 12 m/s to 24 m/s, the power spectral density at the tower’s natural frequency (0.22 Hz) more than doubled. Notably, TMDs exhibited robust vibration damping capabilities under high wind speeds. Specifically, at wind speeds of 24 m/s, TMDs reduced anterior–posterior and lateral displacement at the tower top by 61.2% and 166.8%, respectively, when two TMDs were combined. Conversely, the study found that TMDs did not significantly improve vibration damping at lower to moderate wind speeds. This research underscores the importance of optimizing TMDs for high wind conditions to ensure wind turbine stability and mitigate potential vibration-related risks effectively under varying environmental loads, including wind and waves. It offers valuable insights for the refined design and deployment of TMDs in wind energy applications.

Seismic performance investigation of PCS water tank designed as tuned mass damper (TMD) for nuclear containment plant considering soil-structure interaction

Tuned mass damper (TMD) has been applied in civil engineering fields to reduce the seismic response. However, few TMDs are used in the nuclear structure due to the huge additional mass of the traditional TMD device on the nuclear structure. In this paper, the PCS water tank of a nuclear structure is reconstructed into a TMD system to reduce the seismic response of the nuclear structure. The proposed novel water tank-TMD device can use its characteristics of large mass to achieve the tuned shock absorption effectively while maintaining the original function of the water tank. Moreover, more and more nuclear power structures are being built on non-bedrock sites, and the effects of soil-structure interaction (SSI) on the seismic response and seismic migration performance of nuclear power structures need to be reasonably considered. The effects of SSI and auxiliary plants on the seismic response of the nuclear containment plants equipped with PCS water tanks are first investigated. Subsequently, the performance of the water tank-TMD system in reducing the seismic responses of nuclear containment plants is analyzed in detail by considering the effect of SSI, design frequency of TMD, and design criteria of TMD. The research results show that the proposed water tank-TMD system can effectively reduce the seismic response of nuclear containment plants. Besides, it is necessary to consider the influence of SSI on the dynamic characteristics of the structure in the design of TMD when the SSI effect is strong. The water tank-TMD system designed according to the TMD criteria proposed by Sadek et al., and Salvi and Rizzi has better reduction performance compared with that designed by other design criteria.

A computationally efficient approach of tuned mass damper design for a nuclear cabinet based on two-step machine learning and optimization methods

Enhancing nuclear power plant (NPP) safety is demanded because of the recent beyond-design-basis earthquake near a NPP. Therefore, research on improving the seismic performance of the electrical cabinet, which ensures the safe operation of NPPs, is needed. In this paper, a tuned mass damper (TMD) is employed to control the seismic response of cabinet. To design the TMD, we employ existing design equations or perform numerical model–based optimization. However, limitations, such as inconsistencies with targeted control of the load and structure, the possibility of converging a local solution, and the high cost of numerical analysis. Therefore, this paper proposes a two-step machine learning and optimization method. Such an approach is utilized to find the optimal global design solution and reduce numerical analysis costs. Each step involves the design of experiment (DOE), response surface, and optimization. Notably, range setting in the DOE accounts for the difference between each step. In the first step, the sampling range is widened to determine the relationship between the design variables and the cabinet's response, and in the second step, the sampling range is narrowed depending on the result of the first step. Consequently, the proposed method reduced the cabinet's response by 35.4 % on average and numerical analysis cost declined by 1/3.

Seismic performance of soft soil foundation with a new type of assembled wall tuned mass damper.

The design of tuned mass damper (TMD) parameters is influenced by the soil-structure-TMD coupling system; thus, it is important to consider the soil-structure interaction (SSI) for the vibration control effect of the TMD. Recently, the acquisition of TMD parameters considering soil-structure interactions has only remained at the theoretical stage, lacking relevant experimental verification. Traditional TMD face the problems of occupying a large building space, increasing construction costs, and non-replaceable components. In this study, an assembled wall-type damping TMD was designed. By comparing the dynamic response of the uncontrolled and controlled structures equipped with the newly assembled wall-type damping TMD in the shaking table test on a soft soil foundation, we analyzed whether the SSI effect was considered in the TMD design parameters on the damping effect of the newly assembled wall-type tuned mass damper. The TMD parameters optimized using the artificial intelligence algorithm were verified experimentally. The results indicated that the traditional TMD design parameters were discordant because the SSI effect was not considered. The SSI effect in the soil effectively reduces the dynamic response of the superstructure. By considering the SSI effect and improving the multi-population genetic algorithm, a wall-type damping TMD with optimized parameters can achieve a good damping effect.

Effect of scour on the fatigue life of offshore wind turbines and its prevention through passive structural control

Abstract. Offshore wind turbine (OWT) support structures are exposed to the risk of fatigue damage and scour, and this risk can be effectively mitigated by installing structural control devices such as tuned mass dampers (TMDs). However, time-varying scour altering OWTs' dynamic characteristics has an impact on the TMD design and fatigue life, which has rarely been studied before. In this paper, a simplified modal model is used to investigate the influence of scour and a TMD on the fatigue life evaluation of a 5 MW OWT's support structure, and a traditional method and a newly developed optimization technique are both presented to obtain TMD parameters. This optimization technique aims at finding optimal parameters of the TMD which maximize the fatigue life of a hotspot at the mudline, and the effect of time-varying scour can be considered. This study assumes that the TMD operates in the fore–aft (FA) direction, while the vibration in the side–side (SS) direction is uncontrolled. Results show that scour can decrease the fatigue life by about 24.1 % and that the TMD can effectively suppress vibration and increase the fatigue life. When the scour depth reaches 1.3 times the pile diameter, the TMD with a mass ratio of 1 % can increase the fatigue life of an OWT's support structure by about 64.6 %. Further, it is found that the fatigue life can be extended by 25 % with the TMD optimized by the proposed optimization technique rather than using a traditional design method which does not take the change in dynamic characteristics into account.

Equivalent continuous method based novel design of a nonlinear TMD with piecewise stiffness

Tuned mass Dampers (TMDs) are extensively used passive control devices for high-rise buildings to mitigate undesirable responses. In practice, limit devices are frequently applied due to the large displacement of TMD, resulting in the emergence of piecewise nonlinearity. In this study, a TMD with piecewise stiffness (PSTMD) is developed to investigate the piecewise nonlinearity, including piecewise linear stiffness (PLS) and piecewise nonlinear stiffness (PNS). Initially, a novel equivalent continuous method (ECM) is proposed based on the principles of the least squares method (LSM) to approximate the PSTMD using a nonlinear TMD with Duffing stiffness. The equivalent nonlinear TMD is proven to be accurate enough to approximate the PSTMD. Subsequently, frequency response analysis is conducted on the PSTMD designed by linear method, results indicate that the linear method fails to design PSTMD. Thirdly, the optimal parameters of PSTMD are determined based on the ECM and the improved design method for nonlinear TMD proposed by the author. Results indicate that this novel design method effectively enhances the performance of PSTMD and mitigates the effect of piecewise nonlinearity. Finally, the influence of parameters of PSTMD on the optimal tuning frequency is investigated. The influence of damping ratio of PSTMD is explored by numerical simulation, with results indicating that employing the damping ratio suggested by traditional linear design method as the optimal parameter is reasonable. In summary, the novel method proposed in this study holds significance for the engineering design of TMDs with piecewise characteristics.

Stability-Based Optimum Design of Tuned Mass Damper using Chaos Game Optimization in Pole Placement Scheme

The present work investigates the optimization of Tuned Mass Dampers (TMDs) for improving the seismic behavior of structures by considering system stability using a well-known robust Chaos Game Optimization (CGO) metaheuristic algorithm. In this regard, a new approach was introduced to locate the system’s poles as an objective function in the optimum design of TMDs. In this scheme, the mechanical parameters of TMD are designed to find the pole placement of the structural system with more stability. This research presents a dynamic analysis and comparative evaluation of various cost functions—including relative controlled drift response, the transfer function (TF) of acceleration response, and pole placement scheme—to determine the most effective design for TMD parameter optimization. Structural control performance indexes are used to compare the seismic behavior of each design. The results demonstrate the cost function based on the pole placement scheme’s capability to enhance TMD design, suggesting valuable theoretical and practical understandings for more resilient and efficient structural designs.

Dynamic vibration control of non-linear buildings using multiple tuned mass dampers

In the field of civil engineering, tuned mass dampers (TMDs) serve as passive devices designed for dynamic vibration control of structures. When dealing with buildings exhibiting nonlinear behavior under dynamic loads, the effectiveness of TMDs may be affected by detuning due to the degradation of the building’s strength. Therefore, addressing the non-linear behavior requires a unique strategy involving the tuning of TMDs to specific time periods following the onset of non-linearity. The proposed approach in this study entails a pushover analysis to establish the pushover capacity curve. The regions between the origin and a target drift of 1/150 are then represented using an idealized trilinear form, with the initial segment corresponding to linearity and subsequent segments capturing non-linear behavior. The second segment spans from the onset of non-linearity to a target drift of 1/400, and the third segment covers the drift range from 1/400 to 1/150. Examining this strategy involves calculating time periods for each segment. Subsequently, three single TMD (STMD) scenarios and one multiple TMD (MTMD) scenario with 3 TMDs, each tuned to time periods corresponding to specific segments of the idealized trilinear, are compared in this study. The evaluation includes non-linear dynamic analysis of 7-story and 25-story reinforced concrete buildings equipped with these TMD scenarios. The floor maximum displacement and peak acceleration results indicate that the STMDs tuned to the time periods corresponding to the non-linear segments exhibit robustness, surpassing the performance of the STMD tuned to the fundamental period. Remarkably, the MTMD scenario demonstrates superior robustness compared to all three STMD scenarios. Further analysis under wind load on the same 25-story building confirms the effectiveness of the MTMDs and STMD tuned to the nonlinearity segment compared to the STMD tuned to the fundamental period. This research provides valuable insights into TMD design for enhanced building performance under non-linear conditions.

Integrated design and real-world application of a tuned mass damper (TMD) with displacement constraints for large offshore monopile wind turbines

Passive tuned mass dampers (TMDs) have been increasingly investigated for vibration control of wind turbines. However, TMD designs based on individual or a few operating conditions may result in insufficient consideration of the TMD's impact on wind turbines. For instance, the influence of end-stop collision forces on the main structural damage may be significantly underestimated, thereby affecting the overall lifecycle evaluation. In this study, focusing on large offshore fixed-bottom monopile wind turbines, we propose an integrated TMD design methodology taking the damper displacement constraints into full account. A comprehensive optimization of the passive omnidirectional pendulum-type TMD is conducted considering large number of operating conditions in the offshore environment. Next, a real-world application of the optimally designed TMD is performed for a 6450 kW monopile offshore wind on the Yellow Sea, China. We develop an on-site testing methodology and evaluation criteria for assessing the effectiveness of the TMD offshore. The results of resonance, emergency stop, operatingand reliability test conditions demonstrate the following: under the optimized TMD design taking into account all operating conditions, the TMD with a mass ratio of 1.56% can offer added damping in the fore-aft and side-side directions of the turbine, and provides the desired damping ratio of 1%; within a 4% frequency range around the design frequency, the TMD achieves effective vibration control; at rated power, the TMD achieves a reduction of more than 50% in the amplitude of the tower base side-side bending moment (Mx). The integrated TMD design with displacement constraints allows for the optimal TMD design across all operating conditions, thereby achieving superior overall vibration control and reduction in fatigue loads. The successful real-world application of the TMD based on integrated design methodology is of high value to the research community.

Optimum design of TMDs for reduction of floor vibration using evolutionary computation

Perceptible floor vibration can arise due to human activities such as walking, especially in steel-framed buildings. A general strategy to reduce floor vibration is to install tuned mass dampers (TMDs) between the floor slab and a raised OA floor. For the TMDs to act effectively, two parameters must be designed properly depending on the dynamic characteristics of the target floor: eigenfrequency and damping ratio. Conventionally, even when installing multiple TMDs in a floor, design has been carried out using fixed-point theory, which was originally used to design a single TMD. With the purpose of improving the performance of multiple-TMD installations, this paper describes the use of evolutionary computation (EC), a mathematical optimization method, to design the parameters for multiple TMDs. The new technique is first verified by implementing a numerical simulation using the spectral element method, a high-efficiency numerical analysis method. TMDs designed with EC are shown to suppress floor vibration more efficiently than those designed with fixed-point theory. Next, in experiments with an actual steel-framed building, sufficient vibration suppression performance is achieved with fewer EC-designed TMDs.

A novel passive nonlinear two-DOF internal resonance-based tuned mass damper

This paper presents a novel passive nonlinear two-degree-of-freedom (DOF) tuned mass damper (TMD) for harmonic vibration suppression. Proposed TMD has two translational modes of vibration. Both of the modes can be active during the vibration because of existing the nonlinear terms in the motion equations and internal resonance phenomenon. The vibration modes of the TMD can become active due to 1:2 internal resonance occurrence. Activation of the both modes during the vibration, helps the nonlinear TMD to have a better performance. Proposed TMD can be designed even by using low damping ratios. Three plans are considered for the design and optimization of the novel TMD. In the first plan, the damping ratios of the TMD are relatively high. Moreover, the jump phenomenon does not take place. In two other plans, the nonlinear TMD system is capable of the jump phenomenon. The performance of the two-DOF nonlinear TMD depends on the excitation amplitude. In the higher excitation amplitudes, proposed TMD can outperform the optimal linear TMD. Finally, a novel mechanical design is presented for the proposed two-DOF TMD which allows it to experience large displacements without any problem. The novel design solves the problems of frequency mistuning in the proposed TMD, and the natural frequency of the TMD can be retuned.

TMD Design by an Entropy Index for Seismic Control of Tall Shear-Bending Buildings.

This study proposes a new arrangement-tuning method to maximize the potential of tuned mass dampers (TMDs) in decreasing the seismic responses of tall buildings. The method relies on a Grammian-based entropy index with the physical meaning of covariance responses to white noise without the involvement of external inputs. A twelve-story RC frame-shear wall building was used as an example to illustrate the method. Indices were computed for the building with TMDs placed on different stories and tuning to different modes and were compared with responses to white noise (colored) time histories. Results showed that greater index reduction cases agree well with greater story-drift reductions cases, despite the differences in the time step of the white noises and structural model types (pure shear vs. shear-bending), and the optimal TMD is not necessarily the traditional "roof-1st mode tuning" case. Comparisons were also made for the shear-bending building under seven earthquake excitations. It is found that, though TMDs are not full-band effective controllers, the index-selected TMDs still perform the best in three out of seven earthquakes. So, the proposed internal-property-based entropy index provides a good controller design for large-scale structures under unpredictable none-stationary excitations.

Tuned Mass Damper Design for Vortex-Induced Vibration Control of a Bridge: Influence of Vortex-Induced Force Model

Existing studies optimized the tuned mass damper (TMD) for vortex-induced vibration (VIV) control of bridges based on an empirical linear model or Scanlan’s nonlinear model, which cannot accurately simulate the effect of the vortex-induced force and hence results in a TMD design that lacks effectiveness or robustness. Four vortex-induced force models are considered to systematically analyze the influence of force models on TMD design for VIV control. The design results based on various vortex-induced force models, as well as three design formulas, are compared in terms of effectiveness and robustness. Numerical results suggest that the empirical linear model and Scanlan’s nonlinear model significantly underestimate the TMD mass ratio required to suppress the VIV amplitude to be lower than a threshold. The empirical linear model may overestimate the robustness of the TMD to changing the frequency ratio, while Scanlan’s nonlinear model may overestimate or underestimate the robustness depending on the threshold VIV amplitude. The TMD design based on the polynomial model is considered more accurate since it can accurately predict VIV responses at various effective damping levels. The aerodynamic envelope model can be used as a convenient model for TMD optimization. The results generated using the free vibration formula are the closest to that of the polynomial model. An appropriate safety factor should be considered to convert the TMD design based on sectional model experiments to real bridges.

Parameter design and performance evaluation of tuned mass damper (TMD) for seismic control of structure considering soil-structure interaction (SSI)

Tuned mass damper (TMD) is a practical tool for reducing structural vibration. The current TMD design often use the dynamic characteristics of structures with fixed base. However, in terms of resisting earthquakes especially when the soil-structure interaction (SSI) effect is prominent, the TMD designed for the fixed base situation behaves unfavorably and even amplifies the structural response. In this paper, a parameter design and performance evaluation of TMD for seismic control of structure considering SSI is studied. The contents include the SSI modeling, structural dynamic characteristic identification, and TMD parameter designing. A seismic SSI model that the soil is simulated by an accurate lumped parameter models (LPMs) is built firstly. A simple and practical method is then used to identify the structural dynamic characteristic of SSI model. The identified structural frequency is used to compute the parameters of TMD. Finally, two types of structures, three kinds of soils, and 100 ground motions are applied to comprehensively evaluate the TMD performance through the comparison with the fixed-ground-based design and optimization-algorithm-based design. The research shows the TMD designed by the proposed method can show a good performance and robustness.

Tuned Mass Damper Design of Substation Post Switchgear in Gale Area

Post switchgear of substation in a gale area is a typical wind-sensitive structure. In order to reduce the wind-induced response of substation post switchgear in a gale area, in this paper, according to the theoretical formula of the optimal frequency ratio and the optimal damping ratio of TMD given by Den Hartog, a tuned mass damper (TMD) is proposed to reduce the vibration of the first-order vibration mode outside the plane of the structure. The Simulink simulation model of the simplified structure with TMD is established and the fluctuating wind speed of the equipment is simulated by the Kaimal wind speed spectrum. The wind vibration control effect of TMD is checked, and the rationality of the TMD design is verified.

Tuned Mass Dampers in Tall Buildings: A Practical Performance-Based Design Approach

Tuned mass dampers (TMDs) are increasingly being used to reduce the motion of tall buildings during common wind events. Despite TMDs receiving extensive theoretical research for many decades, dissemination of the practical aspects of designing and installing these devices is severely lacking. Since they are relatively new to the high-rise construction industry, TMD installations may be viewed by design and construction teams as having considerable risk. This paper describes the process of implementing a TMD in a tall building to demystify the devices for practicing structural engineers, architects, general contractors, and owners. It is hoped that this demystification will help these parties understand and control the real and perceived risks associated with TMD implementations. Since prescriptive, code-based procedures are unsuitable for TMD design, a performance-based design approach must be used to ensure the TMD attains specified performance objectives. The TMD implementation process is described in four phases: concept design, detailed design, fabrication and installation, and tuning and commissioning. This paper does not present new theoretical or experimental research but instead provides a broad, practical overview of real-world TMD installations for practitioners. The content of this paper has been obtained from the design and installation of dozens of TMDs in tall buildings around the world.

Transient response reduction of floating offshore wind turbine subjected to sudden mooring line failure

Floating offshore wind turbine (FOWT) is subjected to different dynamic loads during its lifetime. It is essential to ensure the safety of FOWT against these loads to avoid the economic losses. In the past, a majority of the studies focused on reducing the effect of dynamic loads due to wind and waves. This paper explores the application of a tuned mass damper (TMD) for reducing the transient response of FOWT during the mooring line failure. The FOWT is subjected to sudden loads when there is a mooring line breakage. The response control of FOWT during such an event is of immense importance to avoid the catastrophic failure. Although TMD is usually designed for vibration reduction in a steady state, this work focuses on transient response reduction. The investigations are carried out for a case where TMD is placed in the nacelle of FOWT. A reduced-order model is used for the TMD design. An optimum TMD is obtained by minimizing the H∞ norm of the system response when subjected to external disturbances. The designed TMD performance is assessed by carrying out a coupled nonlinear dynamic analysis using aero-hydro-servo-elastic code, OpenFAST. Three different environmental conditions corresponding to below-rated, near-rated, and near-cut-out wind speeds are considered for the analysis. The effectiveness of the TMD is assessed for the scenario of single, double, and triple mooring line failure. The performance indices, defined in terms of peak, root mean square, and standard deviation of the FOWT responses are evaluated for each of the cases. The designed TMD is found to be advantageous for reducing the transient response of FOWT during the mooring line failure. Therefore, the TMD can be effectively used for transient response reduction and enhancing the safety of FOWT in the event of accidental mooring line failure.

Robust optimum design of tuned mass dampers for high-rise buildings subject to wind-induced vibration

<p style='text-indent:20px;'>Control devices are commonly applied to suppress structural displacement due to dynamic loads. In this work, a study of the optimum tuned mass dampers (TMDs) design was carried out, installed in a high-rise building subject to wind-induced vibration. Tuned mass dampers are the most known passive energy device and their design are an important area of study. A mathematical model to consider the wind force in the time domain was introduced. A procedure to obtain the robust design of tuned mass dampers was proposed through the optimization under uncertainties, which considers the uncertainties present in the structural properties of the building and also in the dynamic excitation. This method led to the robust design of TMDs, whereas the device performance became insensitive to the randomness of the input variables of the optimization problem. The robust design was compared with a design obtained by a deterministic optimization and the advantages of using an optimization under uncertainties are shown. In addition, the proposed methodology was compared with traditional TMD design methods, showing again the superiority of the proposed methodology.</p>

Optimal Design Formula for Tuned Mass Damper Based on an Analytical Solution of Interaction between Soil and Structure with Rigid Foundation Subjected to Plane SH-Waves

The tuned mass damper (TMD) is widely used for vibration mitigation, especially in high-rise buildings where significant soil-structure interaction (SSI) effects are usually involved. This creates a need to consider SSI effects in TMD design. In this work, a novel design framework for TMD systems with SSI effects is proposed. For response evaluations, structure-TMD systems are modeled as a two-degrees-of-freedom (2DOF) system, standing on a rigid foundation and subject to out-of-plane SH seismic wave inputs in a homogeneous half-space. Closed-form analytical solutions of its displacement and acceleration responses are derived, and the H2-norm of the system transfer function is introduced to quantify the performances of TMDs. The TMD design problem is then formulated and solved by optimizing the performances. Considering that aspects other than response mitigation, e.g., strokes, damper device costs, etc., may be critical to TMD damping ratios, a design framework is developed by firstly making an informed selection on TMD damping ratios, and subsequently tuning TMD frequency ratios through calibrated formulae. In addition, TMD strokes versus TMD damping ratios are investigated to facilitate the determination of TMD damping ratios. A case study based on a real-existing building system is carried out to illustrate the application of the proposed design framework. The framework has proven to be highly efficient and effective and suitable to for use in practical engineering.

Effectiveness of isolated vertical extension of masonry buildings as nonconventional TMD

In this paper, the strategy of Intermediate Isolation System (IIS) is proposed for the vertical extension of an aggregate of masonry buildings located in Pozzuoli, south Italy. The effectiveness of IIS working as a nonconventional Tuned Mass Damper (TMD) for the existing construction is assessed in terms of reduction of seismic demand and damage in the masonry structure undergoing inelastic deformation under seismic input. For this aim, a general step-by-step procedure is first defined and then applied to the case study building. In particular, the characterization of dynamic behaviour and seismic capacity of the building aggregate is first addressed through modal and push over analyses. Elastic parametric analyses are then carried out on lumped mass models to derive the so-called nonconventional TMD design spectrum and to define the design configurations of the isolated vertical addition that minimize the global seismic response of the overall structure. The effectiveness of the retrofit solutions is evaluated and compared to the AS-IS structure through nonlinear time history analyses; structural performance indexes accounting for both peak response and accumulated damage are defined and utilised for this purpose. The results of the time history analyses show that when the masonry structure rests in the elastic field, the displacements in the existing structure decrease, particularly for IIS solutions characterised by low-medium periods. When the masonry exhibits nonlinear behaviour, the effectiveness in terms of displacement reduction is not as significant as in the elastic range but the accumulated damage in the masonry structure is always mitigated.