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R S Jangid - One of the best experts on this subject based on the ideXlab platform.

  • optimum viscous damper for connecting adjacent sdof structures for harmonic and stationary white noise random excitations
    Earthquake Engineering & Structural Dynamics, 2007
    Co-Authors: A V Bhaskararao, R S Jangid
    Abstract:

    The dynamic behaviour of two adjacent single-degree-of-freedom (SDOF) structures connected with a viscous damper is studied under base Acceleration. The base Acceleration is modelled as harmonic excitation as well as stationary white-noise random process. The governing equations of motion of the connected system are derived and'solved for relative displacement and Absolute Acceleration responses of connected structures. The response of structures is found to be reduced by connecting with a viscous damper having appropriate damping. For undamped SDOF structures, the closed-form expressions for optimum damping of viscous damper for minimum steady state as well as minimum mean square relative displacement and Absolute Acceleration of either of the connected SDOF structures are derived. The optimum damper damping is found to be functions of mass and frequency ratio of two connected structures. Further, numerical results had indicated that the damping of the connected structures does not have noticeable effects on the optimum damper damping and the corresponding optimized response. This implies that the derived closed-form expressions for optimum damper damping of undamped structures can also be used in practical applications for damped structures.

  • Optimum viscous damper for connecting adjacent SDOF structures for harmonic and stationary white‐noise random excitations
    Earthquake Engineering & Structural Dynamics, 2007
    Co-Authors: A V Bhaskararao, R S Jangid
    Abstract:

    The dynamic behaviour of two adjacent single-degree-of-freedom (SDOF) structures connected with a viscous damper is studied under base Acceleration. The base Acceleration is modelled as harmonic excitation as well as stationary white-noise random process. The governing equations of motion of the connected system are derived and'solved for relative displacement and Absolute Acceleration responses of connected structures. The response of structures is found to be reduced by connecting with a viscous damper having appropriate damping. For undamped SDOF structures, the closed-form expressions for optimum damping of viscous damper for minimum steady state as well as minimum mean square relative displacement and Absolute Acceleration of either of the connected SDOF structures are derived. The optimum damper damping is found to be functions of mass and frequency ratio of two connected structures. Further, numerical results had indicated that the damping of the connected structures does not have noticeable effects on the optimum damper damping and the corresponding optimized response. This implies that the derived closed-form expressions for optimum damper damping of undamped structures can also be used in practical applications for damped structures.

  • Optimum friction pendulum system for near-fault motions
    Engineering Structures, 2005
    Co-Authors: R S Jangid
    Abstract:

    The analytical seismic response of multi-story buildings isolated by the friction pendulum system (FPS) is investigated under near-fault motions. The superstructure is idealized as a linear shear type flexible building. The governing equations of motion of the isolated structural system are derived and the response of the system to the normal component of six recorded near-fault motions is evaluated by the step-by-step method. The variation of top floor Absolute Acceleration and sliding displacement of the isolated building is plotted under different system parameters such as superstructure flexibility, isolation period and friction coefficient of the FPS. The comparison of results indicated that for low values of friction coefficient there is significant sliding displacement in the FPS under near-fault motions. In addition, there also exists a particular value of the friction coefficient of FPS for which the top floor Absolute Acceleration of the building attains the minimum value. Further, the optimum friction coefficient of the FPS is derived for different system parameters under near-fault motions. The criterion selected for optimality is the minimization of both the top floor Acceleration and the sliding displacement. The optimum friction coefficient of the FPS is found to be in the range of 0.05 to 0.15 under near-fault motions. In addition, the response of a bridge seismically isolated by the FPS is also investigated and it is found that there exists a particular value of the friction coefficient for which the pier base shear and deck Acceleration attain the minimum value under near-fault motions.

A V Bhaskararao - One of the best experts on this subject based on the ideXlab platform.

  • optimum viscous damper for connecting adjacent sdof structures for harmonic and stationary white noise random excitations
    Earthquake Engineering & Structural Dynamics, 2007
    Co-Authors: A V Bhaskararao, R S Jangid
    Abstract:

    The dynamic behaviour of two adjacent single-degree-of-freedom (SDOF) structures connected with a viscous damper is studied under base Acceleration. The base Acceleration is modelled as harmonic excitation as well as stationary white-noise random process. The governing equations of motion of the connected system are derived and'solved for relative displacement and Absolute Acceleration responses of connected structures. The response of structures is found to be reduced by connecting with a viscous damper having appropriate damping. For undamped SDOF structures, the closed-form expressions for optimum damping of viscous damper for minimum steady state as well as minimum mean square relative displacement and Absolute Acceleration of either of the connected SDOF structures are derived. The optimum damper damping is found to be functions of mass and frequency ratio of two connected structures. Further, numerical results had indicated that the damping of the connected structures does not have noticeable effects on the optimum damper damping and the corresponding optimized response. This implies that the derived closed-form expressions for optimum damper damping of undamped structures can also be used in practical applications for damped structures.

  • Optimum viscous damper for connecting adjacent SDOF structures for harmonic and stationary white‐noise random excitations
    Earthquake Engineering & Structural Dynamics, 2007
    Co-Authors: A V Bhaskararao, R S Jangid
    Abstract:

    The dynamic behaviour of two adjacent single-degree-of-freedom (SDOF) structures connected with a viscous damper is studied under base Acceleration. The base Acceleration is modelled as harmonic excitation as well as stationary white-noise random process. The governing equations of motion of the connected system are derived and'solved for relative displacement and Absolute Acceleration responses of connected structures. The response of structures is found to be reduced by connecting with a viscous damper having appropriate damping. For undamped SDOF structures, the closed-form expressions for optimum damping of viscous damper for minimum steady state as well as minimum mean square relative displacement and Absolute Acceleration of either of the connected SDOF structures are derived. The optimum damper damping is found to be functions of mass and frequency ratio of two connected structures. Further, numerical results had indicated that the damping of the connected structures does not have noticeable effects on the optimum damper damping and the corresponding optimized response. This implies that the derived closed-form expressions for optimum damper damping of undamped structures can also be used in practical applications for damped structures.

Tao Peng - One of the best experts on this subject based on the ideXlab platform.

  • primary resonance analysis and vibration suppression for the harmonically excited nonlinear suspension system using a pair of symmetric viscoelastic buffers
    Nonlinear Dynamics, 2018
    Co-Authors: Hong Zhang, Wenjun Meng, Ronghui Zhang, Kening Li, Tao Peng
    Abstract:

    To reduce the severity of high-magnitude vibrations and shock, end-stop buffers was used for the most suspension cabs or seats of work vehicles. This paper employs a pair of symmetric linear viscoelastic end-stops to improve the performance of a single-degree-of-freedom nonlinear suspension system under primary resonance conditions, which has cubic nonlinearity. Firstly, a piecewise symmetry tri-nonlinear model is introduced. The frequency response of relative displacement corresponding to the steady-state motion is obtained by applying the multiple-scale method, which is found to be the same with the averaging method solution. And it is further verified by numerical simulation. Its stability is then studied. Subsequently, a design criterion is proposed for jump avoidance, which is caused by the saddle-node bifurcation. Also, parametric studies are carried out to illustrate effects of design parameters for the end-stop on the isolation performance at primary resonance, including responses of the relative displacement and the Absolute Acceleration. The results show that with dynamic parameters properly designed by using viscoelastic end-stops, the relative displacement response can be effectively suppressed and the jump can be eliminated for both hardening and softening primary isolators. Besides, the end-stop can effectively attenuate the Absolute Acceleration response for a hardening primary isolator, while more damping is needed to attenuate that for a softening primary isolator, although the degree of the softening nonlinearity is mitigated. It is suggested that a moderate stiffness compared to that of the primary isolator and also a high damping of the end-stop be beneficial to both vibration isolation and jump avoidance under primary resonance conditions.

Hong Zhang - One of the best experts on this subject based on the ideXlab platform.

  • primary resonance analysis and vibration suppression for the harmonically excited nonlinear suspension system using a pair of symmetric viscoelastic buffers
    Nonlinear Dynamics, 2018
    Co-Authors: Hong Zhang, Wenjun Meng, Ronghui Zhang, Kening Li, Tao Peng
    Abstract:

    To reduce the severity of high-magnitude vibrations and shock, end-stop buffers was used for the most suspension cabs or seats of work vehicles. This paper employs a pair of symmetric linear viscoelastic end-stops to improve the performance of a single-degree-of-freedom nonlinear suspension system under primary resonance conditions, which has cubic nonlinearity. Firstly, a piecewise symmetry tri-nonlinear model is introduced. The frequency response of relative displacement corresponding to the steady-state motion is obtained by applying the multiple-scale method, which is found to be the same with the averaging method solution. And it is further verified by numerical simulation. Its stability is then studied. Subsequently, a design criterion is proposed for jump avoidance, which is caused by the saddle-node bifurcation. Also, parametric studies are carried out to illustrate effects of design parameters for the end-stop on the isolation performance at primary resonance, including responses of the relative displacement and the Absolute Acceleration. The results show that with dynamic parameters properly designed by using viscoelastic end-stops, the relative displacement response can be effectively suppressed and the jump can be eliminated for both hardening and softening primary isolators. Besides, the end-stop can effectively attenuate the Absolute Acceleration response for a hardening primary isolator, while more damping is needed to attenuate that for a softening primary isolator, although the degree of the softening nonlinearity is mitigated. It is suggested that a moderate stiffness compared to that of the primary isolator and also a high damping of the end-stop be beneficial to both vibration isolation and jump avoidance under primary resonance conditions.

Daiki Sato - One of the best experts on this subject based on the ideXlab platform.

  • Automatic determination of LQR weighting matrices for active structural control
    Engineering Structures, 2018
    Co-Authors: Kou Miyamoto, Jinhua She, Daiki Sato, Nobuaki Yasuo
    Abstract:

    Abstract This paper presents a method for the automatic selection of weighting matrices for a linear-quadratic regulator (LQR) in order to design an optimal active structural control system. The weighting matrices of a control performance index, which are used to design optimal state-feedback gains, are usually determined by rule of thumb or exhaustive search approaches. To explore an easy way to select optimal parameters, this paper presents a method based on Bayesian optimization (BO). A 10-degree-of-freedom (DOF) shear building model that has passive-base isolation (PBI) under the building is used as an example to explain the method. A control performance index that contains the Absolute Acceleration, along with the inter-story drift and velocity of each story, is chosen for the design of the controller. An objective function that contains the maximum Absolute Acceleration of the building is chosen for BO to produce optimal weighting matrices. In the numerical example, a restriction on the displacement of the PBI is used as a constraint for the selection of weighting matrices. First, the BO method is compared to the exhaustive search method using two parameters in the weighting matrices to illustrate the validity of the BO method. Then, thirty-three parameters (which are automatically optimized by the BO method) in the weighting matrices are used to elaborately tune the controller. The control results are compared to those for the exhaustive search method and conventional optimal control, in terms of the control performance of the relative displacement, Absolute Acceleration, inter-story-drift angle, and the story-shear coefficient of each story. The damping ratio for each mode, and the control energy and power are also compared. The comparison demonstrates the validity of the method.

  • active structural control with suppression of Absolute Acceleration using equivalent input disturbance approach
    International Symposium on Industrial Electronics, 2018
    Co-Authors: Kou Miyamoto, Jinhua She, Daiki Sato
    Abstract:

    This paper presents a new control system that suppresses not only the relative displacement, but also the Absolute Acceleration of a structure. It uses the modified-equivalent-input-disturbance (MEID) approach to design a control system. The control of the Absolute Acceleration is very important to protect properties and people from a large earthquake, and has been considered to be a difficult problem. To deal with this problem, this study constructed a modified EID control system to achieve satisfactory control performance.

  • ISIE - Active Structural Control with Suppression of Absolute Acceleration Using Equivalent-Input-Disturbance Approach
    2018 IEEE 27th International Symposium on Industrial Electronics (ISIE), 2018
    Co-Authors: Kou Miyamoto, Jinhua She, Daiki Sato
    Abstract:

    This paper presents a new control system that suppresses not only the relative displacement, but also the Absolute Acceleration of a structure. It uses the modified-equivalent-input-disturbance (MEID) approach to design a control system. The control of the Absolute Acceleration is very important to protect properties and people from a large earthquake, and has been considered to be a difficult problem. To deal with this problem, this study constructed a modified EID control system to achieve satisfactory control performance.