tuned mass damper

Determining the optimal parameters of TMD has a great effect on improving the seismic behavior of long span bridges. Parameters such as mass, damping ratio, angular frequency of damper and geometric characteristics of the structure change the seismic performance of the bridge. The main purpose of this paper is to provide design aid formulas to determine optimal properties of the damper to reduce the seismic response along the longitudinal axis of suspension bridges, taking into account the effects of soil-structure interaction. Therefore, various models of suspension bridges with a constant total length on two types of subsoil (stiff and soft soil) considered under the effect of near field earthquake records. Different values of the ratio of the length of side span to the middle span of the bridges (α) have been assumed. The optimal characteristics of the damper for the bridge has been determined by assuming a mass ratio of 2% for the damper according to different values of α and for each type of soil. Design aid formulas based on those results extracted. Then the effectiveness of the proposed formulas has been evaluated by evaluating them for designing TMD to improve the performance of three different bridge models. The results show the acceptable accuracy of the design aid formulas to determine the efficient values of damping percentage and angular frequency of TMD. Furthermore, it has been observed that by changing the soil stiffness, the optimal parameters and seismic performance of tuned mass damper will be changed to a significant extent. For instance, TMD reduces 40% and 24% the maximum deflection of the bridge deck in stiff and soft soil with respect.

Tuned mass dampers (TMDs) are a combination of mass, spring, and damper that are added to a structure to reduce its response to lateral excitation, such as wind forces and earthquake excitation, especially in the displacement range. Due to the very rich frequency content of earthquake excitation, the use of TMDs in steel moment frames does not necessarily improve the structural behavior under all earthquake excitations. Exclamation The time-history method is a new nonlinear dynamic method for estimating the behavior of structures under earthquake excitation. In this analysis method, the structure is subjected to an artificial incremental excitation. The results of the nonlinear time history analysis show that the TMD reduces the average maximum roof displacement under selected ground motion records. The performance of the TMD also improves with increasing mass ratio and increasing building height. Adding a TMD to steel moment frames reduces the average maximum roof acceleration under selected ground motion records and also reduces the average maximum base shear of the building. The time-history method estimation of the maximum roof displacements of the structure at a hazard level equivalent to a 475-year return period earthquake is also 10% to 20% less than the nonlinear time-history method. Exclamation The time-history method estimation of the maximum roof acceleration of the structure at a hazard level equivalent to a 475-year return period earthquake is also 10% to 20% more than the nonlinear time-history method. Exclamation The time-history method estimation of the maximum base shear of the structure at the considered hazard level is also 5% to 15% more than the nonlinear time-history method.

tuned mass dampers are a combination of mass, spring and dampers. tuned mass dampers are set on a specific frequency range, when the structure is subjected to external force in the desired frequency range, TMD reduce the responses of the structure by creating a force against the movement direction of the structure. The most important limitation of TMD is providing a sufficient mass ratio in order to optimally control the structure. The inerter element is an element with two terminals that can produce a force proportional to the acceleration difference created in its two terminals. One of the distinguishing features of this element compared to other structural control tools is the possibility of changing the mass matrix of the structure. Nowadays, extensive research is being done in order to combine the inerter element with structural control systems. Adding an inerter element to conventional tuned mass dampers significantly increases the efficiency of TMD and removes the limitation of TMD to provide a suitable mass ratio. The placement position of the inerter element in the control system is very important. If the inerter element is placed between two inappropriate levels in the system, it will disrupt the function of absorbing dynamic vibrations and cause the responses to intensify. In this research, the optimization of the parameters of the inerter element combination with tuned mass dampers is done using the particle optimization algorithm and with the ability to generalize to all structures

In this paper, a new and efficient performance-based method is introduced for the optimal design of the tuned mass damper (TMD) to control the response of nonlinear structures. In this method, the FEMA-P58 probabilistic evaluation framework is used in the design and evaluation of TMD performance in order to reduce the repair cost and time caused by structural and non-structural damages. For this purpose, an innovative objective function has been defined based on structural responses resulting from different earthquakes, which is compatible with the probability of the repair cost and time exceeding a certain value in the FEMA-P58 method. Uncertainties due to earthquake records are directly considered in the introduced objective function. The genetic algorithm is used for the optimal design of TMD based on the proposed objective function. Also, due to the fact that considering the uncertainties in the input earthquake records leads to increasing the calculation time, therefore the artificial neural network technique is used as a fast estimator of the nonlinear dynamic response of the structure to reduce the calculation time. The probabilistic evaluation of the performance of the structure equipped with the proposed TMD shows the efficiency and effectiveness of the proposed design procedure in reducing the expected repair cost and time. So that the expected repair cost and time in the structure equipped with the proposed TMD under the design earthquake have been reduced by about 29% compared to the uncontrolled structure.

Isolators and dampers are devices that dissipate energy and reduce the seismic response of structures during strong earthquakes. Lead Rubber Bearings (LRBs) and Tuned Mass Dampers (TMDs) are two common types of these devices. Studying non-linear behavior and seismic properties of structural systems equipped with this type of isolators and dampers can significantly enhance understanding of their behavior against lateral forces caused by strong earthquakes. In this study, a 9-story steel structure was analyzed using the Endurance Time Analysis (ETA) method in SAP2000 software with fixed and isolated bases, along with a tuned mass damper with different mass ratios and without a tuned mass damper. The analysis results indicate that the tuned mass damper is highly effective in reducing the displacement of the isolator level, drift ratio, and story shear forces. This effect is more significant with higher mass ratios of the TMD. This effect is more pronounced with higher mass ratios of the TMD. However, reducing the absolute acceleration response of the structure has not been effective, and increasing the mass ratio of the TMD only reduces the performance of the control system in improving the absolute acceleration response compared to the isolated state.

Tuned mass damper(TMD) is an efficient tool to control wind-induced vibrations of tall buildings. Previous studies on the effect of TMD are generally limited to specific conditions. In the present study, the effect of the mass and installation height of TMD on the wind-induced vibration control of tall buildings are investigated. An example of tall building with the height 400 m and square variable cross section is presented. The analytical model of the building is assumed as a multi-degrees-of-freedom vertical cantilever beam with the masses lumped at the nodes. The wind-induced responses of the structure are computed using the frequency domain analysis and the random vibration method for a wide range of studied parameters. The results indicated that the vibrations of the structure and TMD system decreases with increasing the mass of the TMD. For instance, the 100 and 600-ton TMD installed at top-floor reduced the top-floor crosswind acceleration by 31 and 48 percent, respectively. By increasing the installation height, the control effectiveness of the system increases, while the vibration of the TMD does not change considerably. For a 300-ton TMD installed at 320 and 400 m heights, the crosswind acceleration reduced by 33.72 and 41.28 percent and the RMS displacement of the TMD at these heights were 58.68 and 54.92 cm, respectively.

In this paper, the performance of Tuned Mass Damper (TMD) control system in seismic response reduction of a four-span integral bridge is investigated. Two classic analytical methods and one optimization method are then employed to calculate TMD parameters. Then, the effect of selecting each of the three methods for calculating TMD parameters on the seismic response of the bridge is studied. Three objective functions are considered for optimization procedure in MATLAB. After calculating TMD parameters, nonlinear dynamic analysis of the bridge in transverse direction is carried out in OpenSees. The purpose of this study is to compare different methods in obtaining damper parameters and to introduce a method that calculates damper parameters in such a way that the damper has a better performance on the bridge. Numerical results indicate performance of the damper is affected by its parameters and selecting the objective function. It is recommended to use the optimization method for calculate the damper parameters with maximum lateral displacement of the deck midpoint objective function. Also the results show that the more reduction of the response is related to the response corresponding to the objective function. For the studied bridge, the maximum values of reduction of displacement and acceleration of the middle deck are equal to 22.4 and 17.7%, respectively, and for the base shear is 4.3%. Therefore, the lateral displacement of the deck midpoint objective function is introduced as the best goal function

Suspension bridges contain high towers due to having long span. Large height makes them to experience remarkable displacement responses against dynamic loading, like seismic excitation which disturbs their performance. In order to overcome this problem, control strategies, like tuned mass damper or in brief TMD as a passive system can be used. The performance of these systems can be addressed by the indices defined according to structural responses. On the other hand, its parameters should be adjusted to their optimum values to providing the best performance accessible by the meta heuristic algorithm. Here, the seismic displacement and energy responses of the Golden gate bridge considering soil-structure interaction were investigated using the optimum TMD optimized by observer teacher learner algorithm, and the performance of it was addressed by the energy indices. The results indicated that by increasing the softness of the bed soil the first mode plays the dominant role in the final response. Also, TMD was a successful system to control the vibration of the tower-pier system according to the defined energy indices for all the conditions of the bed soil considered. Suspension bridges contain high towers due to having long span. Large height makes them to experience remarkable displacement responses against dynamic loading, like seismic excitation which disturbs their performance. In order to overcome this problem, control strategies, like tuned mass damper or in brief TMD as a passive system can be used. The performance of these systems can be addressed by the indices defined according to structural responses.

With the increasing development of military weapons around the world and the variety of explosives, terrorist attacks are a growing threat. The science of vibration control is well developed against natural loads. Although blast loads are different than natural loads, this science can also be used to reduce explosive load responses. For this purpose, passive and semi-active method included tuned mass damper (TMD) and magneto-rheological (MR) damper have been used to reduce the vibrations caused by the blast load in the base-isolated structure. In this study, a type-2 fuzzy system has been used to determine the appropriate voltage of the MR damper so that the existing uncertainties do not adversely affect its performance. The numerical simulation of two explosives with distance of 15m from a system of 5 degrees of freedom, has been performed by theoretical and empirical equations. The use of the proposed control tools along with the base isolation system showed that not only these methods can maintain the proper performance of the base isolated system, but limit the displacement and possible damages at larger excitations. The comparison results showed that the use of MR damper along with the base isolation system can have the best performance against blast and seismic loads. The use of this system on average reduced the maximum drift of the stories to about 36% in blast loads, 68% in far-field earthquakes and 46% in near-field earthquakes, while the drift of the base significantly has been limited than the base-isolated system with a TMD.

Tuned mass dampers (TMDs) are being increasingly used for protection of structures against seismic and environmental loads. An important step in design and application of TMDs is the evaluation of TMD parameter which can cause be associated with serious difficulties. In this paper, we attempt to provide a framework to evaluate the modal parameters of TMDs using a combination of experimental test on shake table and a relatively recent modal analysis technique, namely Frequency Domain Decomposition (FDD). In order to achieve this, a series of test were conducted on a 5-storey steel frame was subjected to excitations from two scaled earthquakes (Imperial Valley and Kobe) ) while damped using two TMDs with mass ratios of 0.01 and 0.1.Mounted instrumentations recorded the structural response during the earthquakes and the recorded response was then used for an operational modal analysis (OMA) in order to estimate the dynamic characteristics of the TMDs. The FDD technique was used in this paper which was employed to estimate the parameters of TMDs. The damping ratios obtained from FDD method was compared with classical methods to verify its accuracy and capabilities in extraction of the modal parameters of TMDs. This paper shows that the use of shake table experiments coupled with the post-experiment modal analysis can be successfully used in TMD design and enables the researchers and practitioners to accurately estimate and test the response of the structures under relatively realistic conditions, which consequently allows low-cost testing of TMDs for optimum TMD selection.

Due to structural safety and residential comfort, the vibration control of tall buildings under earthquake and wind excitations has always been one of the important issues in the structural engineering context. One of the well-established approaches for controlling the structural vibration is the use of Tuned Mass Dampers (TMD) employed with different methods in structures. In this paper, a 10-story shear building with linear behavior is studied under twenty eight far-field and near-field earthquakes in MATLAB. Active Tuned Mass Damper (ATMD) is used to control the structural vibration. According to the earthquake excitation random nature, Fuzzy Logic and Mamdani Inference System are applied to determine the control force. In addition, the Particle Swarm Optimization (PSO) algorithm is used to determine the optimum TMD actuator power, and in this optimization, the effect of the actuator saturation is also considered. Furthermore, a method is introduced for robust optimum design of the suggested controller. Using the proposed control system and the optimum actuator power, structural responses decline about 44 pct. Additionally, due to the existence of uncertainty in earthquake records, applying a controller with average actuator power generally results in 33 pct. structural response reduction, and the performance of the active controlled system always outperforms the passive controlled system with 16 pct. structural response reduction.

Tuned Mass Dampers, TMDs, often reduce the displacement response of structures by influencing their first mode of vibration. The structure of these dampers consists of three main parameters: mass, damping, and stiffness. Since the parameters of TMDs are constant during the vibrations, optimal tuning of these parameters is very important. Finding the optimal values of the key parameters for a TMD in nonlinear structures using numerical methods involves numerous nonlinear dynamic analyses; therefore, the computations would be time-consuming. Recent studies, carried out on the application of TMDs in building structures, have mainly focused on reducing the lateral displacements of building structures. However in this research, the application of TMDs and their effectiveness are investigated for cables of the power transmission tower in both lateral and vertical directions simultaneously. In order to numerically study the behavior of the power transmission tower, the structure of the telescopic steel tower is modeled in the OpenSEES software and to reduce the volume of computation, a numerical search method is used to find the optimal values for the parameters of the TMDs to minimize the lateral displacement in the middle of the cable span. The mass ratio of the TMDs is equal to 0.5% of the total mass of the structure. Using this mass ratio, numerical analyses of the system indicate that the maximum reduction of lateral displacement at the middle of the cable mitigated due to implementing TMDs is about 50% under the applied earthquakes with 0.5g maximum acceleration.

Tuned mass damper is a common tool in passive control, which is used in many structures. However, with all the proper features, its most important functional limitation is the weakness against broad band excitation. Various methods have been proposed to overcome this problem, among which using hysteretic damping of materials with nonlinear behavior is known effective. Among materials with nonlinear behavior, shape memory alloys have good features and large hysteresis loops. Hence, in this paper, using nonlinear stiffness and hysteretic damping of a shape memory alloy spring, linear stiffness and viscous damping of a common tuned mass damper are replaced. Then, the modified damper has been used to control responses of a single degree of freedom structure under harmonic loadings and the effect of the loading amplitude on the control of the structural responses was determined. Subsequently, the damper has been used to control seismic responses of single degree of freedom structures to compare its performance under broad band seismic loadings with the performance of conventional tuned mass dampers. Results of the analyses show that the characteristics of shape memory alloys can adequately control the impact of the loading amplitude on the performance of nonlinear mass dampers. Also, the presence of hysteretic damping can significantly improve control of seismic responses of single degree degrees of freedom structures compared to conventional tuned mass dampers, provided that dynamic properties of the nonlinear mass damper take their optimal values.

One of the challenges in the field of civil engineering is to mitigate the seismic vibration of structures induced by dynamic loads, such as earthquake and strong wind in order to prevent undesirable damages causing human discomfort and economic consequence. The vibration control systems can be categorized as passive, active and semi-active. In recent years, semi-active control systems demonstrate better control effects than both passive and active systems. Semi-active control devices can behave as passive devices in the event of a power loss, and are therefore more reliable and consume less power than the active systems. In this study, to evaluate the effectiveness of the semi-active tuned mass damper using MR damper and a fuzzy logic controller, the nonlinear model of the nine-story benchmark structure is subjected to earthquake excitation. The semi-active tuned mass damper consists of a 1000 kN magnetorheological damper and the damping force of the MR damper is controlled by the fuzzy logic controller.The Bouc–Wen model is utilized to model the dynamic behavior of the MR damper. For this purpose, the increment dynamic analysis (IDA) is conducted to consider the effectiveness of the maximum acceleration of two near- and far-field acceleration records on the performance of the control systems. Two near-field earthquake acceleration records including Kobe (1995) and Northridge (1994) and two far-field earthquake acceleration records including El Centro (1940) and Hachinohe (1968) are used in this study. To achieve the optimum parameters of tuned mass damper, a numerical search method is used to reduce the displacement of the last floor of the structure. The optimal mass ratio, damping and the frequency of the tuned mass damper of these analysis for this structure are 3.5 %, 10 % and 2 rad/s. Also, this benchmark structure is modeled in OpenSees and the fuzzy inference system was implemented in MATLAB. In order to implement the semi-active control system, it’s necessary to communicate between OpenSees and MATLAB. For this purpose TCP-IP method is used. The displacement and velocity response of the ninth floor of structure equipped with tunned mass damper are considered as the input values for the fuzzy inference system. Furthermore, the required voltage of MR damper in this floor is defined as the output parameter of the fuzzy system. Moreover, the membership functions of fuzzy control are triangle and trapezoidal functions. The obtained results of the FLC are compared with the those of passive controlled structure. Therefore, absolute displacement and acceleration values of the last floor of the structure, the maximum relative displacement and the base shear values are investigate. The results showed that the FLC reduces the maximum last floor displacement, the maximum relative displacement and the maximum base shear by 17.75 %, 15.88 % and 16.85 % as compared to the uncontrolled structure, respectively and also, it reduces those responses by 3.62 %, 1.17 % and 15.76 % as compared to the passive response, respectively. Furtheremore, the fuzzy control system has effective performance than the passive system to decrease the maximum and residual displacement of the stories. On the other hand, the fuzzy control system has a low performance in reducing the maximum last floor acceleration.

Controlling the maximum acceleration and displacement of the roof within the acceptable range is important and essential. In order to control structures, a number of control systems have been introduced that are categorized into four system including active, passive, semi active and hybrid system. One of the most used passive systems is the tuned mass damper system which is placed on the roof of structure for controlling the behavior of building. In addition, the optimization of structures subjected to the earthquake load is an essential task for the safe and economic design of structures. It must be noted that earthquakes are random phenomena and the precise prediction of forthcoming events is a hard task. However, in seismic design codes, the static and modal seismic methods for the seismic design of structures are adopted by the design spectrum produced based on previous earthquakes. Hence, in order to overcome this problem, the concept of critical excitation as a robust method has been presented and developed to generate worst–case critical excitations. The critical excitation method have been presented in the framework of an optimization problem to maximize the structural responses subjected to some constraints. In this paper, an effective method is presented to determine the optimum values for the parameters of the tuned mass damper system subjected to critical earthquakes. The critical earthquakes are unique and are computed based on the dynamical properties of the structure. For this purpose, based on the obtained information from the past occurred earthquakes the critical earthquakes of a ten story shear building are established subjected to the constraints. The constraint scenarios include some computable properties of the ground motion such as energy, peak ground acceleration an upper bound Fourier amplitude spectrum. In fact, in this stage, to compute the critical earthquakes an inverse nonlinear constraint optimization problem must be solved for each time step. Then, the building equipped by a tuned mass damper system at roof of the structure (controlled building) is considered and the optimal design of tuned mass damper subjected to critical earthquakes are implemented. The maximum absolute displacement and acceleration of the roof are considered as the objective functions. Finally, among the computed earthquakes, one of them which produces the maximum objective functions is selected as the critical earthquake. In the optimization procedure, the mass, damping and stiffness of the tuned mass damper (TMD) system are adopted as the design variables. Multi-objective particle swarm optimization method is used to optimize the parameters of the tuned mass damper system. Since, the optimal design of the tuned mass damper system is presented as a multi-objective optimization problem, a set of optimal solutions are obtained. Numerical examples demonstrate the ability and efficiency of the proposed method in the optimal design of the tuned mass damper system subjected to the critical earthquakes. In addition, the numerical results show that the maximum absolute values of the displacement and acceleration of the roof efficiently decreases when the building is controlled by the optimum tuned mass damper system. Also, the results show that the severe earthquake needs a bigger mass for tuned mass damper in order to control the displacement and acceleration of the roof.