• Title/Summary/Keyword: passive dampers

Search Result 165, Processing Time 0.024 seconds

Critical earthquake input energy to connected building structures using impulse input

  • Fukumoto, Yoshiyuki;Takewaki, Izuru
    • Earthquakes and Structures
    • /
    • v.9 no.6
    • /
    • pp.1133-1152
    • /
    • 2015
  • A frequency-domain method is developed for evaluating the earthquake input energy to two building structures connected by viscous dampers. It is shown that the earthquake input energies to respective building structures and viscous connecting dampers can be defined as works done by the boundary forces between the subsystems on their corresponding displacements. It is demonstrated that the proposed energy transfer function is very useful for clear understanding of dependence of energy consumption ratios in respective buildings and connecting viscous dampers on their properties. It can be shown that the area of the energy transfer function for the total system is constant regardless of natural period and damping ratio because the constant Fourier amplitude of the input acceleration, relating directly the area of the energy transfer function to the input energy, indicates the Dirac delta function and only an initial velocity (kinetic energy) is given in this case. Owing to the constant area property of the energy transfer functions, the total input energy to the overall system including both buildings and connecting viscous dampers is approximately constant regardless of the quantity of connecting viscous dampers. This property leads to an advantageous feature that, if the energy consumption in the connecting viscous dampers increases, the input energies to the buildings can be reduced drastically. For the worst case analysis, critical excitation problems with respect to the impulse interval for double impulse (simplification of pulse-type impulsive ground motion) and multiple impulses (simplification of long-duration ground motion) are considered and their solutions are provided.

The study of frictional damper with various control algorithms

  • Mirtaheri, Masoud;Samani, Hamid Rahmani;Zandi, Amir Peyman
    • Earthquakes and Structures
    • /
    • v.12 no.5
    • /
    • pp.479-487
    • /
    • 2017
  • Frictional dampers are used in structural engineering as means of passive control. Meanwhile, frictional damper shave a disadvantage compared to viscous rivals since the slippage force must be exceeded to activate the device, and cannot be ideal full range of possible events. The concept of semi-active control is utilized to overcome this shortcoming. In this paper, a new semi-active frictional damper called Smart Adjustable Frictional (SAF) damper is introduced. SAF damper consists of hydraulic, electronic units and sensors which are all linked with an active control discipline. SAF acts as a smart damper which can adapt its slippage threshold during a dynamic excitation by measuring and controlling the structural response. The novelty of this damper is, while it controls the response of the structure in real time with acceptable time delay. The paper also reports on the results of a series of experiments which have been performed on SAF dampers to obtain their prescribed hysteretic behavior for various control algorithms. The results show that SAF can produce the desired slippage load of various algorithms in real time. Numerical models incorporating control simulations are also made to obtain the hysteretic response of the system which agrees closely with test results.

Vibration isolation with smart fluid dampers: a benchmarking study

  • Batterbee, D.C.;Sims, N.D.
    • Smart Structures and Systems
    • /
    • v.1 no.3
    • /
    • pp.235-256
    • /
    • 2005
  • The non-linear behaviour of electrorheological (ER) and magnetorheological (MR) dampers makes it difficult to design effective control strategies, and as a consequence a wide range of control systems have been proposed in the literature. These previous studies have not always compared the performance to equivalent passive systems, alternative control designs, or idealised active systems. As a result it is often impossible to compare the performance of different smart damper control strategies. This article provides some insight into the relative performance of two MR damper control strategies: on/off control and feedback linearisation. The performance of both strategies is benchmarked against ideal passive, semi-active and fully active damping. The study relies upon a previously developed model of an MR damper, which in this work is validated experimentally under closed-loop conditions with a broadband mechanical excitation. Two vibration isolation case studies are investigated: a single-degree-of-freedom mass-isolator, and a two-degree-of-freedom system that represents a vehicle suspension system. In both cases, a variety of broadband mechanical excitations are used and the results analysed in the frequency domain. It is shown that although on/off control is more straightforward to implement, its performance is worse than the feedback linearisation strategy, and can be extremely sensitive to the excitation conditions.

Vibration Control of Stay Cable Using Smart Passive Damping System (스마트 수동 감쇠 시스템을 이용한 사장 케이블의 진동 제어)

  • Jung Hyung-Jo;Cho Sang-Won;Jang Ji-Eun;Lee In-Won
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 2005.04a
    • /
    • pp.497-504
    • /
    • 2005
  • Stay cables, such as are used in cable-stayed bridges, are prone to vibration due to their low inherent damping characteristics. Several methods have been proposed and implemented to mitigate this problem, though each has its limitations. Recently some studies have shown that active and semiactive control system using MR (Magnetorheological) damper can potentially achieve both higher performance levels than passive control system and adaptability with few of the detractions. However, a control system including a power supply, controller, and sensors is required to maximize the performance of the MR damper and this complicated control system is not effective to most of large civil structures. This paper proposes a smart passive damping system using MR dampers by introducing electromagnetic induction (EMI) system as an external power source to MR damper and verified the performance of smart passive damping system for mitigating the vibration of stay cables. The performances of smart passive damping system are compared with those of linear viscous damper and passive-mode MR damper.

  • PDF

Performance comparison of passive control schemes for the numerically improved ASCE cable-stayed bridge model

  • Domaneschi, Marco;Martinelli, Luca
    • Earthquakes and Structures
    • /
    • v.3 no.2
    • /
    • pp.181-201
    • /
    • 2012
  • The benchmark on the ASCE cable-stayed bridge has gathered since its proposal the interest of many specialists in the field of the structural control and the dynamic response of long span bridges. Starting from the original benchmark statement in the MATLAB framework, a refined version of the bridge model is developed in the ANSYS commercial finite element environment. A passive structural control system is studied through non linear numerical analyses carried out in time domain for several seismic realizations in a multiple support framework. An innovative electro-inductive device is considered. Its positive performance is compared with an alternative version considering traditional metallic dampers.

Equivalent damping of a structure with vibration control devices subjected to wind loads

  • Hwang, Jae-Seung;Kim, Jinkoo;Lee, Sang-Hyun;Min, Kyung-Won
    • Wind and Structures
    • /
    • v.6 no.4
    • /
    • pp.249-262
    • /
    • 2003
  • The purpose of this study is to propose a procedure for evaluating quantitatively the increase of the equivalent damping ratio of a structure with passive/active vibration control systems subjected to a stationary wind load. A Lyapunov function governing the response of a structure and its differential equation are formulated first. Then the state-space equation of the structure coupled with the secondary damping system is solved. The results are substituted into the differential equation of the Lyapunov function and its derivative. The equivalent damping ratios are obtained from the Lyapunov function of the combined system and its derivative, and are used to assess the control effect of various damping devices quantitatively. The accuracy of the proposed procedure is confirmed by applying it to a structure with nonlinear as well as linear passive/active control systems.

Implementation of Uniform Deformation Theory in semi-active control of structures using fuzzy controller

  • Mohammadi, Reza Karami;Haghighipour, Fariba
    • Smart Structures and Systems
    • /
    • v.19 no.4
    • /
    • pp.351-360
    • /
    • 2017
  • Protection of structures against natural hazards such as earthquakes has always been a major concern. Semi-active control combines the reliability of passive control and versatility and adaptability of active control. So it has recently become a preferred control method. This paper proposes an algorithm based on Uniform Deformation Theory to mitigate vulnerable buildings using magneto-rheological (MR) damper. Due to the successful performance of fuzzy logic in control of systems and its simplicity and intrinsically robustness, it is used here to regulate MR dampers. The particle swarm optimization (PSO) algorithm is also used as an adaptive method to develop a fuzzy control algorithm that is able to create uniform inter-story drifts. Results show that the proposed algorithm exhibited a desirable performance in reducing both linear and nonlinear seismic responses of structures. Performance of the presented method is indicated in compare with passive-on and passive-off control algorithms.

Hybrid Structural Control System Design Using Preference-Based Optimization (선호도 기반 최적화 방법을 사용한 복합 구조 제어 시스템 설계)

  • Park, Won-Suk;Park, Kwan-Soon;Koh, Hyun-Moo
    • Proceedings of the Earthquake Engineering Society of Korea Conference
    • /
    • 2006.03a
    • /
    • pp.401-408
    • /
    • 2006
  • An optimum design method for hybrid control systems is proposed in this study. By considering both active and passive control systems as a combined or a hybrid system, the optimization of the hybrid system can be achieved simultaneously. In the proposed approach, we consider design parameters of active control devices and the elements of the feedback gain matrix as design variables for the active control system. Required quantity of the added dampers are also treated as design variables for the passive control system. In the proposed method, the cost of both active and passive control devices, the required control efforts and dynamic responses of a target structure are selected as objective functions to be minimized. To effectively address the multi-objective optimization problem, we adopt a preference-based optimization model and apply a genetic algorithm as a numerical searching technique. As an example to verify the validity of the proposed optimization technique, a wind-excited 20-storey building with hybrid control systems is used and the results are presented.

  • PDF

Optimal design of wind-induced vibration control of tall buildings and high-rise structures

  • Li, Qiusheng;Cao, Hong;Li, Guiqing;Li, Shujing;Liu, Dikai
    • Wind and Structures
    • /
    • v.2 no.1
    • /
    • pp.69-83
    • /
    • 1999
  • The most common used control device on tall buildings and high-rise structures is active and passive tuned mass damper (ATMD and TMD). The major advantages of ATMD and TMD are discussed. The existing installations of various passive/active control devices on real structures are listed. A set of parameter optimization methods is proposed to determine optimal parameters of passive tuned mass dampers under wind excitation. Simplified formulas for determining the optimal parameters are proposed so that the design of a TMD can be carried out easily. Optimal design of wind-induced vibration control of frame structures is investigated. A thirty-story tall building is used as an example to demonstrate the procedure and to verify the efficiency of ATMD and TMD with the optimal parameters.

Evaluation of genetic algorithms for the optimum distribution of viscous dampers in steel frames under strong earthquakes

  • Huang, Xiameng
    • Earthquakes and Structures
    • /
    • v.14 no.3
    • /
    • pp.215-227
    • /
    • 2018
  • Supplemental passive control devices are widely considered as an important tool to mitigate the dynamic response of a building under seismic excitation. Nevertheless, a systematic method for strategically placing dampers in the buildings is not prescribed in building codes and guidelines. Many deterministic and stochastic methods have been proposed by previous researchers to investigate the optimum distribution of the viscous dampers in the steel frames. However, the seismic performances of the retrofitted buildings that are under large earthquake intensity levels or near collapse state have not been evaluated by any seismic research. Recent years, an increasing number of studies utilize genetic algorithms (GA) to explore the complex engineering optimization problems. GA interfaced with nonlinear response history (NRH) analysis is considered as one of the most powerful and popular stochastic methods to deal with the nonlinear optimization problem of damper distribution. In this paper, the effectiveness and the efficiency of GA on optimizing damper distribution are first evaluated by strong ground motions associated with the collapse failure. A practical optimization framework using GA and NRH analysis is proposed for optimizing the distribution of the fluid viscous dampers within the moment resisting frames (MRF) regarding the improvements of large drifts under intensive seismic context. Both a 10-storey and a 20-storey building are involved to explore higher mode effect. A far-fault and a near-fault earthquake environment are also considered for the frames under different seismic intensity levels. To evaluate the improvements obtained from the GA optimization regarding the collapse performance of the buildings, Incremental Dynamic Analysis (IDA) is conducted and comparisons are made between the GA damper distribution and stiffness proportional damping distribution on the collapse probability of the retrofitted frames.