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Agathoklis Giaralis - One of the best experts on this subject based on the ideXlab platform.

  • optimal tuned Mass Damper inerter tmdi design for seismically excited mdof structures with model uncertainties based on reliability criteria
    Structural Control & Health Monitoring, 2018
    Co-Authors: Agathoklis Giaralis, Alexandros A Taflanidis
    Abstract:

    The tuned Mass-Damper-inerter (TMDI) is a recently proposed linear passive dynamic vibration absorber for the seismic protection of buildings. It couples the classical tuned Mass Damper (TMD) with an inerter, a two-terminal device resisting the relative acceleration of its terminals, in judicial topologies, achieving Mass-amplification and higher-modes-damping effects compared to the TMD. This paper considers an optimum TMDI design framework accommodating the above effects while accounting for parametric uncertainty to the host structure properties, modeled as a linear multi degree of freedom system, and to the seismic excitation, modeled as stationary colored noise. The inerter device constant, acting as a TMD Mass amplifier, is treated as a design variable, whereas performance variables sensitive to high-frequency structural response dynamics are used to account for the TMDI influence to the higher structural modes. Reliability criteria are adopted for quantifying the structural performance, expressed through the probability of occurrence of different failure modes related to the trespassing of acceptable thresholds for the adopted performance variables: floor accelerations, interstory drifts, and attached Mass displacement. The design objective function is taken as a linear combination of these probabilities following current performance-based seismic design trends. Analytical and simulation-based tools are adopted for the efficient estimation of the underlying stochastic integral defining the structural performance under uncertainty. A 10-story building under stationary Kanai-Tajimi stochastic excitation is considered to illustrate the design framework for various TMDI topologies and attached Mass values. It is shown that the TMDI achieves enhanced structural performance and robustness to building and excitation uncertainties compared to same Mass/weight TMDs.

  • wind induced vibration mitigation in tall buildings using the tuned Mass Damper inerter
    Journal of Structural Engineering-asce, 2017
    Co-Authors: Agathoklis Giaralis, Francesco Petrini
    Abstract:

    In this paper the classical linear tuned Mass-Damper (TMD) is coupled with an inerter, a two-terminal device resisting the relative acceleration of its terminals, in various tuned Mass-Damper-inerter (TMDI) topologies to suppress excessive wind-induced oscillations in tall buildings causing occupants’ discomfort. A parametric numerical study is undertaken involving a top-floor-TMD-equipped planar frame capturing accurately the in-plane dynamic behavior of a 74-storey benchmark building exposed to a quasi-stationary spatially-correlated wind-force field accounting for vortex shedding effects in the across-wind direction. It is found that the TMDI reduces the peak top floor acceleration more effectively than the TMD by considering smaller attached Mass values, and TMDI topologies in which the inerter spans more stories in linking the attached Mass to the host structure. Moreover, the inclusion of the inerter reduces dramatically the TMD stroke while it was verified that the magnitude of the developing inerter forces can be readily accommodated by the host structure. Pertinent illustrative examples are included showcasing that the TMDI meets code-prescribed serviceability design requirements for new tall buildings using significantly smaller attached Mass compared to the TMD, and that inerter devices can be used to upgrade the performance of existing TMD-equipped tall buildings without changing the attached Mass.

  • wind induced vibration mitigation in tall buildings using the tuned Mass Damper inerter tmdi
    Journal of Structural Engineering-asce, 2017
    Co-Authors: Agathoklis Giaralis, Francesco Petrini
    Abstract:

    In this paper the classical linear tuned Mass-Damper (TMD) is coupled with an inerter, a two-terminal device resisting the relative acceleration of its terminals, in various tuned Mass-Damper-inerter (TMDI) topologies to suppress excessive wind-induced oscillations in tall buildings causing occupants’ discomfort. A parametric numerical study is undertaken involving a top-floor-TMD-equipped planar frame capturing accurately the in-plane dynamic behavior of a 74-storey benchmark building exposed to a quasi-stationary spatially-correlated wind-force field accounting for vortex shedding effects in the across-wind direction. It is found that the TMDI reduces the peak top floor acceleration more effectively than the TMD by considering smaller attached Mass values, and TMDI topologies in which the inerter spans more stories in linking the attached Mass to the host structure. Moreover, the inclusion of the inerter reduces dramatically the TMD stroke while it was verified that the magnitude of the developing inerter forces can be readily accommodated by the host structure. Pertinent illustrative examples are included showcasing that the TMDI meets code-prescribed serviceability design requirements for new tall buildings using significantly smaller attached Mass compared to the TMD, and that inerter devices can be used to upgrade the performance of existing TMD-equipped tall buildings without changing the attached Mass.

  • the tuned Mass Damper inerter for harmonic vibrations suppression attached Mass reduction and energy harvesting
    Smart Structures and Systems, 2017
    Co-Authors: Laurentiu Marian, Agathoklis Giaralis
    Abstract:

    In this paper the tuned Mass-Damper-inerter (TMDI) is considered for passive vibration control and energy harvesting in harmonically excited structures. The TMDI couples the classical tuned Mass-Damper (TMD) with a grounded inerter: a two-terminal linear device resisting the relative acceleration of its terminals by a constant of proportionality termed inertance. In this manner, the TMD is endowed with additional inertia, beyond the one offered by the attached Mass, without any substantial increase to the overall weight. Closed-form analytical expressions for optimal TMDI parameters, stiffness and damping, given attached Mass and inertance are derived by application of Den Hartog’s tuning approach to suppress the response amplitude of force and base-acceleration excited single-degree-of-freedom structures. It is analytically shown that the TMDI is more effective from a same Mass/weight TMD to suppress vibrations close to the natural frequency of the uncontrolled structure, while it is more robust to detuning effects. Moreover, it is shown that the Mass amplification effect of the inerter achieves significant weight reduction for a target/predefined level of vibration suppression in a performance-based oriented design approach compared to the classical TMD. Lastly, the potential of using the TMDI for energy harvesting is explored by substituting the dissipative Damper with an electromagnetic motor and assuming that the inertance can vary through the use of a flywheel-based inerter device. It is analytically shown that by reducing the inertance, treated as a Mass/inertia-related design parameter not considered in conventional TMD-based energy harvesters, the available power for electric generation increases for fixed attached Mass/weight, electromechanical damping, and stiffness properties.

  • optimum design of the tuned Mass Damper inerter for serviceability limit state performance in wind excited tall buildings
    Procedia Engineering, 2017
    Co-Authors: Agathoklis Giaralis, Francesco Petrini
    Abstract:

    Optimally designed tuned Mass-Damper-inerters (TMDIs) are considered to meet code-prescribed serviceability criteria in typical wind-excited tall buildings subject to vortex shedding effects in a performance-based design context. The TMDI, couples the classical tuned-Mass-Damper (TMD) with an inerter, a two-terminal device resisting the relative acceleration of its terminals, achieving Mass-amplification and higher-modes-damping effects compared to the TMD. A benchmark 74-storey building is considered, where TMDI is added to the structural system assuming ideal linear inerter behavior. The wind action is defined through a non-diagonal power spectral density matrix supporting computationally efficient frequency domain structural analyses. The TMDI is optimally designed for stiffness, damping, and inerter constant parameters via a standard numerical optimization search, for a range of pre-specified attached TMDI Mass values. It is shown that the TMDI achieves more lightweight construction in the design of new code-compliant tall buildings against wind.

Francesco Petrini - One of the best experts on this subject based on the ideXlab platform.

  • wind induced vibration mitigation in tall buildings using the tuned Mass Damper inerter
    Journal of Structural Engineering-asce, 2017
    Co-Authors: Agathoklis Giaralis, Francesco Petrini
    Abstract:

    In this paper the classical linear tuned Mass-Damper (TMD) is coupled with an inerter, a two-terminal device resisting the relative acceleration of its terminals, in various tuned Mass-Damper-inerter (TMDI) topologies to suppress excessive wind-induced oscillations in tall buildings causing occupants’ discomfort. A parametric numerical study is undertaken involving a top-floor-TMD-equipped planar frame capturing accurately the in-plane dynamic behavior of a 74-storey benchmark building exposed to a quasi-stationary spatially-correlated wind-force field accounting for vortex shedding effects in the across-wind direction. It is found that the TMDI reduces the peak top floor acceleration more effectively than the TMD by considering smaller attached Mass values, and TMDI topologies in which the inerter spans more stories in linking the attached Mass to the host structure. Moreover, the inclusion of the inerter reduces dramatically the TMD stroke while it was verified that the magnitude of the developing inerter forces can be readily accommodated by the host structure. Pertinent illustrative examples are included showcasing that the TMDI meets code-prescribed serviceability design requirements for new tall buildings using significantly smaller attached Mass compared to the TMD, and that inerter devices can be used to upgrade the performance of existing TMD-equipped tall buildings without changing the attached Mass.

  • wind induced vibration mitigation in tall buildings using the tuned Mass Damper inerter tmdi
    Journal of Structural Engineering-asce, 2017
    Co-Authors: Agathoklis Giaralis, Francesco Petrini
    Abstract:

    In this paper the classical linear tuned Mass-Damper (TMD) is coupled with an inerter, a two-terminal device resisting the relative acceleration of its terminals, in various tuned Mass-Damper-inerter (TMDI) topologies to suppress excessive wind-induced oscillations in tall buildings causing occupants’ discomfort. A parametric numerical study is undertaken involving a top-floor-TMD-equipped planar frame capturing accurately the in-plane dynamic behavior of a 74-storey benchmark building exposed to a quasi-stationary spatially-correlated wind-force field accounting for vortex shedding effects in the across-wind direction. It is found that the TMDI reduces the peak top floor acceleration more effectively than the TMD by considering smaller attached Mass values, and TMDI topologies in which the inerter spans more stories in linking the attached Mass to the host structure. Moreover, the inclusion of the inerter reduces dramatically the TMD stroke while it was verified that the magnitude of the developing inerter forces can be readily accommodated by the host structure. Pertinent illustrative examples are included showcasing that the TMDI meets code-prescribed serviceability design requirements for new tall buildings using significantly smaller attached Mass compared to the TMD, and that inerter devices can be used to upgrade the performance of existing TMD-equipped tall buildings without changing the attached Mass.

  • optimum design of the tuned Mass Damper inerter for serviceability limit state performance in wind excited tall buildings
    Procedia Engineering, 2017
    Co-Authors: Agathoklis Giaralis, Francesco Petrini
    Abstract:

    Optimally designed tuned Mass-Damper-inerters (TMDIs) are considered to meet code-prescribed serviceability criteria in typical wind-excited tall buildings subject to vortex shedding effects in a performance-based design context. The TMDI, couples the classical tuned-Mass-Damper (TMD) with an inerter, a two-terminal device resisting the relative acceleration of its terminals, achieving Mass-amplification and higher-modes-damping effects compared to the TMD. A benchmark 74-storey building is considered, where TMDI is added to the structural system assuming ideal linear inerter behavior. The wind action is defined through a non-diagonal power spectral density matrix supporting computationally efficient frequency domain structural analyses. The TMDI is optimally designed for stiffness, damping, and inerter constant parameters via a standard numerical optimization search, for a range of pre-specified attached TMDI Mass values. It is shown that the TMDI achieves more lightweight construction in the design of new code-compliant tall buildings against wind.

Michela Basili - One of the best experts on this subject based on the ideXlab platform.

  • a generalized 2 dof model for optimal design of mdof structures controlled by tuned Mass Damper inerter tmdi
    International Journal of Mechanical Sciences, 2020
    Co-Authors: Daniele Pietrosanti, M De Angelis, Michela Basili
    Abstract:

    Abstract The paper illustrates a methodology to perform the optimal design of a Tuned Mass Damper Inerter (TMDI) equipped on a multi degree of freedom (MDOF) structure through a generalized model. The TMDI is considered in both configurations grounded and ungrounded. A generalized 2-DOF model is obtained: the primary oscillator, representing the original MDOF structure and the secondary oscillator, representing the control system. A Gaussian zero mean white noise random process is adopted for the excitation. The TMDI design is carried out adopting an energy objective function, maximized over the space of the design parameters which are: the Mass and inertance ratios, the frequency ratio, the damping factor and a parameter that accounts for the TMDI location on the MDOF structure. Synthetic performance-based design maps of the TMDI parameters are carried out. It is shown that is possible to have different design configurations to achieve a target performance level. The maps furnish, as limit cases, the design of a Tuned Inerter Damper (TID) and a Tuned Mass Damper (TMD), when the Mass or the inertance ratios are respectively assumed null. It is shown straightforwardly the regions of the design parameters where the inerter enhances the performances achievable by classical TMD. Furthermore, an analytical expression which links the optimal design variables necessary to obtain a desired target performance is proposed. Frequency response functions and modal parameters of certain 2-DOF models with optimally designed control system are reported and considerations on how the design parameters influence the system dynamics and the damping capabilities are highlighted. Comparisons of the TMDI optimally designed with cases of no control and same Mass TMD are evidenced throughout the paper. Finally, the main responses of the primary structure and the TMDI are estimated in the space of variation of the design parameters in order to assess the effectiveness of the control system.

  • optimal design and performance evaluation of systems with tuned Mass Damper inerter tmdi
    Earthquake Engineering & Structural Dynamics, 2017
    Co-Authors: Daniele Pietrosanti, M De Angelis, Michela Basili
    Abstract:

    Summary The paper concerns the optimal design and performance evaluation of a Tuned Mass Damper Inerter (TMDI) to reduce dynamic vibrations. The system exploits properties of the inerter, a two-terminal mechanical device able to produce a force proportional to the relative acceleration between terminals, with the ability of generating an apparent Mass even two orders of magnitude greater than its own physical Mass. A primary single-degree-of-freedom structure is equipped with a classical linear Tuned Mass Damper (TMD), the secondary structure, whose Mass is connected to the ground via an inerter. The optimal design of the TMDI is conducted by assuming a white noise process as base input and utilizing three different design methodologies: displacement minimization, acceleration minimization and maximization of the ratio between the energy dissipated in the secondary system and the total input energy. Optimal results obtained with the different methodologies are carried out and compared. Two limit cases are also considered when the inerter is not contemplated: conventional and non-conventional TMDs, characterized by a low and a large Mass ratio, respectively. The TMDI performance is evaluated and compared with conventional and non-conventional TMDs; moreover, its robustness is assessed with a sensitivity analysis varying the design parameters. Attention is focused not exclusively on the primary structure response but also on the secondary one. Finally, the effectiveness of the optimally designed TMDI is evaluated having considered earthquake base excitation. Results demonstrate the effectiveness of TMDI systems for dynamic response reduction with superior performances and robustness than classical TMDs. Copyright © 2017 John Wiley & Sons, Ltd.

Chao Sun - One of the best experts on this subject based on the ideXlab platform.

  • bi directional vibration control of offshore wind turbines using a 3d pendulum tuned Mass Damper
    Mechanical Systems and Signal Processing, 2018
    Co-Authors: Chao Sun, Vahid Jahangiri
    Abstract:

    Abstract Offshore wind turbines suffer from excessive bi-directional vibrations due to wind-wave misalignment and vortex induced vibrations. However, most of existing research focus on unidirectional vibration attenuation which is inadequate for real applications. The present paper proposes a three dimensional pendulum tuned Mass Damper (3d-PTMD) to mitigate the tower and nacelle dynamic response in the fore-aft and side-side directions. An analytical model of the wind turbine coupled with the 3d-PTMD is established wherein the interaction between the blades, the tower and the 3d-PTMD is modeled. Aerodynamic loading is computed using the Blade Element Momentum method where the Prandtls tip loss factor and the Glauert correction are considered. JONSWAP spectrum is adopted to generate wave data. Wave loading is computed using Morisons equation in collaboration with the strip theory. Via a numerical search approach, the design formula of the 3d-PTMD is obtained and examined on a National Renewable Energy Lab (NREL) monopile 5 MW baseline wind turbine model under misaligned wind, wave and seismic loading. Dual linear tuned Mass Dampers (TMDs) deployed in the fore-aft and side-side directions are utilized for comparison. It is found that the 3d-PTMD with a Mass ratio of 2 % can improve the mitigation of the root mean square and peak response by around 10 % when compared with the dual linear TMDs in controlling the bi-directional vibration of the offshore wind turbines under misaligned wind, wave and seismic loading.

  • study on semi active tuned Mass Damper with variable damping and stiffness under seismic excitations
    Structural Control & Health Monitoring, 2014
    Co-Authors: Chao Sun, Satish Nagarajaiah
    Abstract:

    SUMMARY In the present study, a semi-active tuned Mass Damper (STMD) with variable damping coefficient and stiffness is evaluated under seismic excitations. Variation of the damping ratio of the STMD is implemented through tracking the displacement of the STMD.If the tracked amplitude of the STMD is increasing, damping ratio of the STMD is set to zero, or else it is set to an appropriate nonzero value. Stiffness of the STMD is tuned through tracking the displacement of the primary structure, which is analyzed using a short-time Fourier transform-based control algorithm. Both far-field and near-fault ground motions are used to examine the effectiveness of the STMD and the control algorithm. Displacement time history and response (displacement and acceleration) spectra are obtained for the cases of an optimal passive TMD and an STMD. It is found that the STMD with variable damping ratio and frequency can effectively attenuate the seismic responses and outperform the optimal passive TMD. In addition, results are obtained for the case that damage occurs to the primary structure during an earthquake. The study indicates that the STMD controlled by the proposed algorithm can rapidly capture the variation of the structure and remains tuned with the primary structure, whereas the optimal TMD becomes off-tuned when damage occurs. Copyright © 2013 John Wiley & Sons, Ltd.

Mark Laier Brodersen - One of the best experts on this subject based on the ideXlab platform.

  • active tuned Mass Damper for damping of offshore wind turbine vibrations
    Wind Energy, 2017
    Co-Authors: Mark Laier Brodersen, Annsofie Bjorke, Jan Becker Hogsberg
    Abstract:

    An active tuned Mass Damper (ATMD) is employed for damping of tower vibrations of fixed offshore wind turbines, where the additional actuator force is controlled using feedback from the tower displacement and the relative velocity of the Damper Mass. An optimum tuning procedure equivalent to the tuning procedure of the passive tuned Mass Damper combined with a simple procedure for minimizing the control force is employed for determination of optimum Damper parameters and feedback gain values. By time domain simulations conducted in an aeroelastic code, it is demonstrated that the ATMD can be used to further reduce the structural response of the wind turbine compared with the passive tuned Mass Damper and this without an increase in Damper Mass. A limiting factor of the design of the ATMD is the displacement of the Damper Mass, which for the ATMD, increases to compensate for the reduction in Mass. Copyright © 2016 John Wiley & Sons, Ltd.