Coupled‐two‐beam discrete model for dynamic analysis of tall buildings with tuned mass dampers including soil–structure interaction

An equivalent coupled‐two‐beam discrete model is developed for time‐domain dynamic analysis of high‐rise buildings with flexible base and carrying any number of tuned mass dampers (TMDs). The equivalent model consists of a flexural cantilever beam and a shear cantilever beam connected in parallel by a finite number of axially rigid members that allows the consideration of intermediate modes of lateral deformation. The equivalent model is applied to a shear wall–frame building located in the Valley of Mexico, where the effects of soil–structure interaction (SSI) are important. The effects of SSI and TMDs on the dynamic properties of the shear wall–frame building are shown considering four types of soil (hard rock, dense soil, stiff soil, and soft soil) and two passive damping systems: a single TMD on its top (1‐TMD) and five uniformly distributed TMDs (5‐TMD). The results showed a great effectiveness of the TMDs to reduce the lateral seismic response and along‐wind response of the shear wall–frame building for all types of soils. Generally speaking, the dynamic response increases as the flexibility of the foundation increases.     

Seismic response control of asymmetric buildings using tuned mass dampers

The aim of the present study is to investigate the efficiency of the torsional tuned mass dampers (T‐TMDs) in response control of asymmetric buildings under bidirectional earthquake ground excitations. The efficiency of the T‐TMDs is compared with bidirectional tuned mass dampers (BTMDs). The T‐TMDs are oriented to the rotation of the structures about vertical axis with a single torsional mass attached to spring–dashpot elements, whereas the BTMD connects a single mass to two orthogonal sets of spring–dashpot elements oriented to principal axes of the building. The buildings are idealized three‐dimensional models with two translational and one torsional degrees of freedom for each floor. Three different configurations (cruciform‐shaped, L‐shaped, and T‐shaped) of multistory buildings are considered. The 5‐, 15‐, and 20‐story buildings with and without the tuned mass damper schemes are subjected to bidirectional earthquake ground excitation. In order to evaluate the effectiveness of the T‐TMDs and BTMD, the rotation, displacement, acceleration, and base shear force responses are computed. Parametric studies are conducted for all the configurations installed with the T‐TMDs and BTMD by varying their mass ratio, damping ratio, and ground motions. It is concluded that the T‐TMDs are more effective in mitigating the torsional response of asymmetric buildings as compared with the BTMD.     

Integrated damping systems for tall buildings: tuned mass damper/double skin facade damping interaction system

As today's tall buildings become ever taller and more slender, wind‐induced vibration is a serious design issue. This paper presents integrated damping systems for tall buildings. An emphasis is placed on investigating the potential of double skin facades (DSF) as an integrated damping system for tall buildings. In the first scheme, the connectors between the inner and outer skins of the DSF system are designed to have low axial stiffness with a damping mechanism. Through this design, vibration of the primary building structure can be substantially reduced. However, excessive movements of the DSF outer skin masses are a design limitation. In the second scheme, the tuned mass damper (TMD) and DSF damping (DSFD) interaction system is studied to mitigate the design limitation of the first scheme and to resolve other TMD‐related design issues. TMDs are usually very large and located near the top of tall buildings for their effective performance. As a result, very valuable occupiable space near the top of tall buildings is sacrificed to contain large TMDs. In addition, installing TMD systems means adding additional masses to tall buildings. Through the TMD/DSFD interaction system, these issues can also be substantially addressed. Compared with the conventional TMD system, the TMD/DSFD interaction system requires a significantly reduced TMD mass ratio to achieve the same target damping ratio. Compared with the first scheme only with the DSFD mechanism, movements of the DSF outer skins can be better controlled in the TMD/DSFD interaction system. Copyright © 2015 John Wiley & Sons, Ltd.     

地震作用下某高层结构MTMD减震控制研究

通过数值模拟研究了地震作用下高层结构多个调谐质量阻尼器(MTMD)减震控制。根据实际工程,利用国际通用软件ETABS建立了结构三维有限元模型,进行了动力特性的分析,得到了结构的前几阶频率;根据不同场地类型,选取了4条典型的地震波;研究了调谐质量阻尼器(TMD)的参数选取和有限元的模拟;运用时程分析方法,分别研究了不同地震作用下高层结构有无控制下的反应。研究结果表明,MTMD对高层结构的减震控制效果明显,场地类型对减震控制效果有一定的影响。所获得的结果为高层结构减震控制设计提供参考和依据。     

Study on self‐adjustable variable pendulum tuned mass damper

Pendulum tuned mass damper (PTMD) is usually used to control the horizontal vibration of a tall building. However, traditional PTMD is highly sensitive to frequency deviation and difficult to adjust its frequency. In order to improve this problem of traditional PTMD and protect a tall building more effectively, a novel PTMD, called self‐adjustable variable pendulum tuned mass damper (SAVP‐TMD), is proposed in this paper. On the basis of the acceleration ratio between TMD and primary structure, the SAVP‐TMD can retune itself by varying the length of the pendulum according to the improved acceleration ratio‐based adjustment algorithm. PTMD and primary structural accelerations are obtained from two accelerometers respectively, and the acceleration ratio is calculated in a microcontroller, then, the stepper motor will adjust the pendulum under the guidance of the microcontroller under a specific harmonic excitation. The improved acceleration ratio‐based adjustment algorithm is proposed and compared to solve the nonconvergent retuning problem. The SAVP‐TMD can be regarded as a passive damper including a frequency adjustment device. A single‐degree‐of‐freedom structure model is used to verify the effectiveness of SAVP‐TMD through both experimental study and numerical simulation. In order to further verify the effect of SAVP‐TMD in the MDOF structure, a five‐storey structure coupled with an SAVP‐TMD is proposed as a case study. The results of experiment, simulation, and case study all show that SAVP‐TMD can retune itself to the primary structural dominant frequency robustly, and the retuned PTMD has a better vibration control effect than the mistuned one.     

Performance of fixed‐parameter control algorithms on high‐rise structures equipped with semi‐active tuned mass dampers

The present study investigates the performance of fixed parameter control algorithms on wind‐excited high‐rise structures equipped with semi‐active tuned mass dampers of variable damping. It has been demonstrated that the algorithms that increase significantly the performance of the controlled structure do so at the expense of damper strokes. When the maximum damper strokes are capped to progressively lower limits, the efficacy of different algorithms, measured through a number of performance objectives, drastically alters totally changing the performance ranking of them and pointing out the need for an extensive study of the interplay between loading, control algorithm and allowable stroke within the design of semi‐active tuned mass dampers devices. 2015 The Authors. The Structural Design of Tall and Special Buildings published by John Wiley & Sons Ltd.     

Finding optimal parameters of tuned mass dampers

In this paper, optimum design of tuned mass damper for seismically excited structures is discussed. In the design process, a benchmark multi‐degree of freedom system is considered, and the performance measure of the optimization criterion is selected as the H₂ and H_∞ norms of the transfer function of the combined tuned mass damper and building system. Differential evolution algorithm is then utilized to minimize these objective functions. The objective function choice on performance and the effectiveness of differential evolution optimization algorithm in comparison with other algorithms in the literature are investigated through numerical simulations. Copyright © 2014 John Wiley & Sons, Ltd.     

结构被动和主动多重调谐质量阻尼器控制策略的发展

广泛评述了被动多重调谐质量阻尼器(MTMD)的研究现状，提出了结构主动多重调谐质量阻尼器(AMTMD)和多重主被动调谐质量阻尼器(MAPTMD)的新控制策略，介绍了从AMTMD和MAPTMD的研究进展，并指出了进一步研究的发展方向。     

Proposed robust tuned mass damper for response mitigation in buildings exposed to multidirectional wind

The most common device for control of tall buildings under wind loads is the tuned mass damper (TMD). However, during their lifetimes, high‐rise and slender buildings may experience natural frequency changes under wind speed, ambient temperatures and relative humidity variations, among other factors, which make the TMD design challenging. In this paper, a proposed approach for the design of robust TMDs is presented and investigated. The approach accounts for structural uncertainties, optimization objectives and input excitation (wind or earthquake). For the use of TMDs in buildings, practical design parameters can be different from the optimum ones. Nevertheless, predetermined optimal parameters for a primary structure with uncertainties are useful to attain design robustness. To illustrate the applicability of the proposed approach, an example of a very slender building with uncertain natural frequencies is presented. The building represents a case study of an engineered design that is instructive. Basically, due to its geometry, the building behaves differently in one lateral direction (cantilever building) than the other (shear building). The proposed approach shows its robustness and effectiveness in reducing the response of tall buildings under multidirectional wind loads. In addition, linear‐quadratic Gaussian and fuzzy logic controllers enhanced the performance of the TMD. Copyright © 2012 John Wiley & Sons, Ltd.     

Performance‐based wind evaluation and strengthening of existing tall concrete buildings in the Los Angeles region: dampers,nonlinear time history analysis and structural reliability

This paper presents a methodology in wind design including in a scientific way the benefits of using dampers and of performing a nonlinear dynamic analysis of tall concrete buildings that are being evaluated and strengthened. It is developed for tall buildings in the Los Angeles region but is without geographic bounds. The uses of equations of structural reliability form this scientific basis. Copyright © 2013 John Wiley & Sons, Ltd.     

Dynamic analysis of space structures with multiple tuned mass dampers

Formulations of the reverberation matrix method (RMM) are presented for the dynamic analysis of space structures with multiple tuned mass dampers (MTMD). The theory of generalized inverse matrices is then employed to obtain the frequency response of structures with and without damping, enabling a uniform treatment at any frequency, including the resonant frequency. For transient responses, the Neumann series expansion technique as suggested in RMM is found to be confined to the prediction of accurate response at an early time. The artificial damping technique is employed here to evaluate the medium and long time response of structures. The free vibration, frequency response, and transient response of structures with MTMD are investigated by the proposed method through several examples. Numerical results indicate that the use of MTMD can effectively alter the distribution of natural frequencies as well as reduce the frequency/transient responses of the structure. The high accuracy, lower computational cost, and uniformity of formulation of RMM are highlighted.     

Parametric study of the use and optimization of tuned mass dampers to control the wind‐ and seismic‐induced responses of a slender monument

Passive energy dissipation devices have been used around the world to mitigate the response of structures under dynamic excitations, such as wind or seismic loading. The use of tuned mass dampers (TMD) in tall and slender buildings to reduce unwanted responses has proved to be very effective. The main purpose of this work is to study the structural behavior of a 115‐m‐height slender monument fitted with TMDs subjected to simulated wind and seismic loading. Turbulent wind forces were calculated based on samples of turbulent wind speed simulated with an auto regressive and moving average (ARMA) model. Ground motions compatible with a seismic site spectrum were also simulated. An optimization approach is suggested to determine the parameters of the TMDs that reduce the structural response to the maximum. The effectiveness of the TMDs for reducing the structural response of the monument is discussed in detail, and the use of optimally tuned TMDs is emphasized.     

Energy‐based predictive algorithm for semi‐active tuned mass dampers

There are various control strategies proposed and implemented for the protection of structures against different types of dynamic excitations. Currently, semi‐active control devices are very popular due to their adaptability and low power requirement. In this paper, a novel energy‐based predictive (EBP) algorithm is proposed, and its effectiveness is studied when applied to semi‐active tuned mass damper (SATMD). The mechanical energy of the primary structure is taken as the key parameter to be used by the algorithm to predict a suitable value of the manipulated variable, the damping of the tuned mass damper (TMD). The choice of the damping is made such that the damping used at a time interval leads to the least possible mechanical energy of the primary structure. The efficacy of the proposed control algorithm is studied by employing the EBP algorithm on single‐story and multistory structures equipped with the SATMD. The performance of the proposed algorithm when applied to the SATMD is also compared with that with the passive TMD for similar parameters. The results of the study show that the implementation of the EBP algorithm leads to significantly reduced dynamic response as compared with the passive TMD. Furthermore, numerical studies are conducted to gain insight into the effect of various parameters such as the mass ratio, the TMD damping ratio, and the flexibility of the structure.     

Study on adaptive‐passive eddy current pendulum tuned mass damper for wind‐induced vibration control

Tuned mass dampers (TMDs) are used to control wind‐excited responses of high‐rise building as traditional vibration control devices. A TMD will have an excellent control effect when it is well tuned. However, a traditional passive TMD is sensitive to the frequency deviation; the mistuning in frequency and damping ratio both will decrease its control effect. In the previous research, an adaptive‐passive variable pendulum TMD (APVP‐TMD) is proposed, which can identify the TMD optimal frequency and retune itself through varying its pendulum length. However, it is found that the frequency variation will change the TMD damping ratio, and an unreasonable damping ratio will lead to a decrement in the robustness of a TMD. In this study, an adaptive‐passive eddy current pendulum TMD (APEC‐PTMD) is presented, which can retune the frequency through varying the pendulum length, and retune the damping ratio through adjusting the air gap between permanent magnets and conductive plates. An adjustable eddy current pendulum TMD (PTMD) is tested, and then, a single‐degree‐of‐freedom (SDOF) primary model with an APEC‐PTMD is built, and functions of frequency and damping ratio retuning are verified. The 76‐story wind‐sensitive benchmark model is proposed in the case study. The original model without uncertainty and ±15% stiffness uncertainty models are considered, and response control effects of different controllers are compared. Results show that because the APEC‐PTMD can both retune its frequency and damping ratio; it is more robust and effective than a passive TMD. It is also found that the APEC‐PTMD has a similar control effect with the active TMD, with little power consumption and better stability.     

Hybrid simulation of a tall building with a double‐decker tuned sloshing damper system under wind loads

This study presents an advanced experimental system, hardware‐in‐the‐loop (HIL), recently referred to as hybrid testing, to validate the effectiveness of a double‐decker tuned sloshing damper (TSD) system with screens applied to a recently constructed tall building. The HIL simulation facilitates a performance analysis of a combined structure‐damper system in which the nonlinear behavior of liquid motion in a TSD is physically modeled, whereas a building system under wind loads that behaves linearly is embedded virtually utilizing a computer model. The scaled model of the TSD is composed of a computer‐controlled system with a shaking table, sensors, and a real‐time communication link. The virtual building system on the computer communicates in real time with the hardware, that is, the physical model of TSD to evaluate on‐the‐fly the performance of a combined building‐TSD system. External excitation including random loading characteristics of winds, waves, or earthquakes can be implemented in HIL to observe the dynamics of the building‐damper system under a host of loading scenarios. An example of a recently completed tall reinforced concrete building with multiple TSDs placed side by side in double‐decker configuration under a suite of external loads and the proposed damping estimation procedure to evaluate the amount of auxiliary damping with TSD for ensuring the TSD design is presented. It examines the habitability of the building in winds and evaluates the effectiveness of the TSD system as well as the efficacy of the first HIL simulation for an actual tall building‐TSD system equipped with screens inside.     

Effects of tuned mass damper on correlation of wind‐induced responses and combination coefficients of equivalent static wind loads of high‐rise buildings

Tuned mass dampers (TMDs) are employed to control the wind‐induced responses of tall buildings. In the meantime, TMD may have an impact on the correlation of wind‐induced responses and combination coefficients of equivalent static wind loads (ESWLs). First, the mass matrix and stiffness matrix were extracted in this paper in accordance with the structural analysis model of two high‐rise buildings, and on that basis, the wind‐induced vibration responses analysis model with and without TMD was established. Second, the synchronous multipoint wind tunnel test to measure the pressure was performed for two high‐rise buildings, and the time history of wind‐induced vibration responses with and without TMD was studied. Finally, the impact of TMD on the correlation of wind‐induced responses and combination coefficients of ESWLs was discussed. The results of two examples suggest that after the installation of TMD, the increase of ρ_xy was 2.1% to 35.0% and ρ_yz was 2.8% to 45.6% at all wind directions for Building 1, and the increase of ρ_xy was 3.9% to 17.1% and ρ_yz was 6.8% to 38.3% for Building 2. The combination coefficients of ESWLs of two buildings were 3% to 6% larger than that of the original structure. The conclusion of this paper can be referenced by the wind resistant design of high‐rise buildings with TMD.     

Seismic response control of base‐isolated buildings using multiple tuned mass dampers

Seismic response of a base‐isolated building equipped with single tuned mass damper (STMD), multiple tuned mass dampers (MTMDs), and distributed multiple tuned mass dampers (d‐MTMDs) under real earthquake ground motions is investigated. Numerical study is carried out using analytical models of five‐, 10‐, and 15‐storey base‐isolated buildings equipped with the STMD, MTMDs, and d‐MTMDs. The buildings are modeled as shear‐type structure with a lateral degree of freedom at each floor level, and the buildings are isolated using the laminated rubber bearing, lead‐core rubber bearing, friction pendulum system, and resilient‐friction base isolator. The coupled differential equation of motion for the buildings are derived and solved in the incremental form using Newmark's step‐by‐step method of integration. From the numerical study conducted, it is concluded that installing a tuned mass damper at each floor level of a base‐isolated building reduces the structural response in terms of top floor acceleration and bearing displacement. It is found that installing the MTMDs and d‐MTMDs are significantly beneficial in reducing top floor acceleration as compared with the STMD. Further, almost comparable reduction in the bearing displacement could be obtained by installing the STMD, MTMDs at top, and d‐MTMDs in the base‐isolated buildings. The d‐MTMDs are more beneficial as compared with the STMD and MTMDs as otherwise huge controller mass can now be divided and distributed on different floor levels.     

Optimum design of tuned mass dampers for different earthquake ground motion parameters and models

Tuned mass dampers are frequently used for passive control of vibrations in civil structures subject to seismic and wind actions. Their efficiency depends on selection of their mechanical properties in relation to main system and excitation characteristics. This paper proposes an optimum design strategy of single tuned mass dampers to control vibrations of principal mode of structures excited by earthquake ground motion. The main purpose of the paper is to investigate the influence of the time modulation of earthquake excitation upon the optimal tuned mass dampers design parameters: frequency and damping ratio. The study is based on numerical analyses carried out with different stochastic models for earthquakes: a simple filtered white noise model and two time modulated filtered white noise models. The numerical analyses are carried out to solve an optimization problem with a performance index defined by the reduction of the standard deviation of either the structure displacement or its inertial acceleration as objective function. To complete the work, the influence of the bandwidth excitation over the values of the optimal tuned mass damper parameters is investigated, as well the optimum mass ratio and the structure frequency. The results of the numeral analyses carried out infer that the earthquake excitation characteristics, including its modulation in time domain, highly affect the optimum tuned mass damper design parameters values.     

Mitigation of tower and out-of-plane blade vibrations of offshore monopile wind turbines by using multiple tuned mass dampers

Offshore wind turbines are vulnerable to external vibration sources such as wind and wave excitations due to the increasing size and flexibility. It is necessary to mitigate the excessive vibrations of offshore wind turbines to ensure the safety and serviceability during their operations. Some research works have been carried out to control the excessive vibrations of the tower and the in-plane vibrations of blades. Very limited study focuses on the out-of-plane vibration mitigation of blades. In the present study, a detailed finite element (FE) model of the latest NREL 5MW wind turbine is developed by using the FE code ABAQUS. The tower and blades are explicitly modelled, and the rotating of the blades is considered. Multiple tuned mass dampers (MTMDs) are proposed to be installed in the tower and each blade to simultaneously mitigate the out-of-plane vibrations of the tower and blades when the wind turbine is subjected to the combined wind and wave loadings. The effectiveness and robustness of the proposed method are systematically investigated. Numerical results show that MTMDs can effectively mitigate the out-of-plane vibrations of the tower and blades when the wind turbine is in either the operational or parked condition.     

Shaking table model test and FE analysis of a reinforced concrete mega‐frame structure with tuned mass dampers

To study the damage characteristics and to evaluate the overall seismic performance of reinforced concrete mega‐frame structures, a shaking table test of a 1/25 scaled model with a rooftop tuned mass damper (TMD) is performed. The maximum deformation and acceleration responses are measured. The dynamic behavior and the damping effect with and without TMD are compared. The results indicate that the mega‐frame structure has excellent seismic performance and the TMD device has a significant vibration reduction effect. A finite element (FE) model simulating the scaled model is also developed, and the numerical and experimental results are compared to provide a better understanding of the overall structural behavior in particular those related to the dynamic characteristics and damping effect. Upon verification of the FE model, other important structural behavior can also be predicted by the FE analysis. Copyright © 2014 John Wiley & Sons, Ltd.