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  • دکتری (1390)

    مهندسی عمران

    دانشگاه تهران، ایران

  • معماری اقلیمی و فنی
  • معماری معاصر
  • معماری فنی
  • معماری سبز

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    Shake table tests of using single-particle impact damper to reduce seismic response

    SM Zahrai, Amir F Rod
    Journal Papers , Volume 16 , Issue 3, 2015 January 1, {Pages 471-487 }

    Abstract

    Whilst the use of impact damper for single-degree-of-freedom (SDOF) systems has received a significant amount of attention, investigations into their interaction with SDOF systems is rare. In this paper, results of a series of experimental analysis of a horizontal particle impact damper under earthquake and sinusoidally excited primary system are investigated. Specific impact damping is determined for a SDOF. The influence of some system parameters such as clearance, stiffness and specific intensity of excitation are investigated experimentally. Driven by the experimental observation, it has been shown that a value of damping capacity was reached with a particle impact damper. The obtained results proved the efficiency of this process for a

    Numerical studies of the conventional impact damper with discrete frequency optimization and uncertainty considerations

    E Dehghan-Niri, SM Zahrai, AF Rod
    Journal PapersScientia Iranica , Volume 19 , Issue 2, 2012 April 1, {Pages 166-178 }

    Abstract

    This paper presents the performance of a single horizontal conventional Impact Damper (ID) in both wide range frequency and resonance excitations. The effects of the coefficient of restitution, e, mass ratio, μ, and clearance, d, on the performance of ID are investigated. The optimal parameters are numerically found by discretely varying the clearance and excitation frequency. The performance of optimal ID is discussed, with respect to different parameters, in both resonance and off-resonance modes. In addition, it is shown how the efficiency of the optimal conventional ID is deteriorated as a result of mistuning in the amplitude and frequency of excitation. This is estimated by suggesting a new criterion of post processing data. It is sho

    Effect of impact damper on SDOF system vibrations under harmonic and impulsive excitations

    SM Zahrai, AF Rod
    Journal PapersJournal of Physics: Conference Series , Volume 181 , Issue 1, 2009 August 1, {Pages 012066 }

    Abstract

    Impact damper is a highly sensitive instrument, which belongs to the category of passive vibration devices used to attenuate the vibration of discrete and continuous systems In this paper, the effect of single unit impact damper on the single degree of freedom system under two different excitations is investigated A study is made of the general behavior of a single particle impact damper; with the main emphasis on sinusoidal and impulse excitations The effects of mass ratio, coefficient of restitution, and gap size are determined by using a MATLAB program.

    ‘The new approach to the design of impact damper vs. harmonic load and comparison of optimum IDopt with TMDopt

    E Dehghan-Niri, S Mehdi Zahrai, Amir F Rod
    Journal PapersProc. of International Conf. on Structural Eng. Dynamics, ICEDyn 2009 , 2009 January , {Pages 22-24 }

    Abstract

    In recent years, considerable attention has been paid to research and the development of structural control devices, with particular emphasis on alleviation of wind and seismic response of buildings and bridges. Structural control technology offers many new ways to protect structures from natural and other types of hazards. In both areas, serious efforts have been undertaken in the last two decades to develop the structural control concept into a workable technology.Passive structural control technology, and in particular, Impact Damping (ID) device, appears to combine the best features of both passive and active control systems and to offer a viable means of protecting civil engineering structural systems against earthquake and wind load.

    SINGLE UNIT IMPACT DAMPER IN HARMONIC AND IMPULSIVE VIBRATIONS

    S Mehdi Zahrai, Amir F Rod
    Journal Papers , January , {Pages }

    Abstract

    Structural control technology offers many new ways to protect structures from natural and other types of hazards. Semiactive structural control technology, appears to combine the best features of both passive and active control systems and to offer a viable means of protecting civil engineering structural systems against earthquake and wind load.[1]An impact damper generally consists of a mass which is allowed to travel freely between two defined stops. Under the right conditions, the vibration of the system to which the impact damper is attached will cause the mass of the impact damper to strike the structure. Therefore, there is a need to understand the particle’s motion, at varying parameters, as it travels between the container’s bo

    EFFECT OF IMPACT DAMPER ON SDOF SYSTEMS VIBRATIONS UNDER DIFFERENT EXCITATIONS

    S Mehdi Zahrai, Amir F Rod
    Journal Papers , January , {Pages }

    Abstract

    Impact damper is a highly sensitive instrument, which belongs to the category of passive vibration devices used to attenuate the vibration of discrete and continuous systems. In this paper, the effect of single unit impact damper on the single degree of freedom system under two different excitations is investigated. A study is made of the general behavior of a single particle impact damper; with the main emphasis on sinusoidal and impulse excitations. The effects of mass ratio, coefficient of restitution, and gap size are determined by using MATLAB program.It is found that the impact damper is an efficient device for reducing the vibration of structures subjected to impulsive and harmonic excitations. Numerical investigations are compared w

    DAMPING CHARACTERISTICS OF IMPACT DAMPER ON SDOF SYSTEM VIBRATIONS UNDER DIFFERENT EXCITATIONS

    S Mehdi Zahrai, Amir F Rod
    Journal Papers , January , {Pages }

    Abstract

    Impact damper is a highly sensitive instrument, which belongs to the category of passive vibration devices used to attenuate the vibration of discrete and continuous systems. In this paper, the effect of single unit impact damper on the single degree of freedom system under two different excitations is investigated. A study is made of the general behavior of a single particle impact damper; with the main emphasis on sinusoidal and impulse excitations. The effects of mass ratio, coefficient of restitution, and gap size are determined by using MATLAB program.It is found that the impact damper is an efficient device for reducing the vibration of structures subjected to impulsive and harmonic excitations. Numerical investigations are compared w

    The Effect of Friction on Response Reduction Using an Impact Damper

    SM Zahrai, Amir F Rod
    Journal Papers , January , {Pages }

    Abstract

    It is already known that the presence of friction does not have adverse effects on the performance of impact dampers with containers of the critical length. It is shown that for shorter containers, friction may introduce stability to the motion of the primary mass, improving the response due to harmonic excitation, and accelerate the attenuation of the amplitude of oscillations for step inputs. The response of a single-particle impact damper is studied in this paper considering friction effect. It is found that the effect of friction on the performance is not generally detrimental, as compared to that for the frictionless case. The effect of friction on the amplitude reduction, velocity discontinuity at impacts is considered.For the specifi

    The Effect of Friction on Response Reduction Using an Impact Damper Impact Damper

    S Mehdi Zahrai, Amir F Rod
    Journal Papers , January , {Pages }

    Abstract

    The response of a single-particle impact damper is studied numerically in this paper considering friction effect. It is found that the effect of friction on the performance is not generally detrimental, as compared to that for the frictionless case.The effect of friction on the amplitude reduction, velocity discontinuity at impacts is considered. It is already known that the presence of friction does not have for shorter containers; friction may introduce stability to the motion of the primary mass, improving the response due to harmonic excitation, and accelerate the attenuation of the amplitude of oscillations for step inputs. For the specific components of a system, a successful design frequently requires identification of the specific m

    Robustness Estimation of Impact Damper Due to Earthquake Excitation

    S Mehdi Zahrai, Amir F Rod
    Journal Papers , January , {Pages }

    Abstract

    In recent years, considerable attention has been paid to research and the development of structural control devices, with particular emphasis on alleviation of wind and seismic response of buildings and bridges. Structural control technology offers many new ways to protect structures from natural and other types of hazards. In both areas, serious efforts have been undertaken in the last two decades to develop the structural control concept into a workable technology.

    Analytical Studies to Reduce Seismic Vibration in Critical Infrastructures Utilizing Impact Damper

    S Mehdi Zahrai, Amir F Rod
    Journal Papers , January , {Pages }

    Abstract

    Impact damper is a highly sensitive instrument, which belongs to the category of passive vibration devices used to attenuate the vibration of discrete and continuous systems.In this paper, the effect of single unit impact damper on the single degree of freedom system under two different excitations is investigated. A study is made of the general behavior of a single particle impact damper; with the main emphasis on sinusoidal and impulse excitations. The effects of mass ratio, coefficient of restitution, and gap size are determined by using MATLAB program.

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