scholarly journals Dynamic Behavior of a Simple Rolling Seismic Isolator with a Position Restoring Device

2018 ◽  
Vol 8 (10) ◽  
pp. 1910 ◽  
Author(s):  
Sung Hong ◽  
Deog-Jae Hur
Keyword(s):  
Numerical Analysis ◽  
Seismic Isolation ◽  
Vibration Suppression ◽  
Equation Of Motion ◽  
Vibration Characteristics ◽  
Design Parameters ◽  
Isolation System ◽  
Runge Kutta Method ◽  
Design Variables ◽  
Fifth Order

Herein, the behavior of a rolling type seismic isolation system with a position restoring device (PRD) is investigated, for alleviating problems such as rapid convergence and position restoration. The equation of motion is derived by modeling the behavior of the seismic isolation system, and the seismic characteristics according to the design variables of the PRD are investigated through numerical analysis. The vibration characteristics of the equation of motion show nonlinearity and depend on different variables. Numerical analysis was performed by using the fourth and fifth order Runge–Kutta method, and the vibration characteristics were analyzed with respect to the design parameters in the rolling type seismic isolation system with PRD, and compared to a model without PRD. In the model with PRD, numerical results show that the vibration suppression capability of the earthquake and the position restoration after disturbance are improved compared to those of the model without PRD. In addition, the rolling type seismic isolation system had nonlinear characteristics at specific frequencies, where the response increases suddenly and harmonics occur. This phenomenon can be controlled by the ratio of mass to stiffness and the damping coefficient, showing that the mount system can be designed to avoid resonance through optimal design.

Study of Parameters Optimization on Seismic Isolated Railway Bridges

2011 ◽  
Vol 50-51 ◽  
pp. 135-139
Author(s):  
Tie Yi Zhong ◽  
Chao Yi Xia ◽  
Feng Li Yang
Keyword(s):  
Optimal Design ◽  
Optimization Design ◽  
Seismic Isolation ◽  
Optimization Method ◽  
Relative Displacement ◽  
Parameters Optimization ◽  
Design Parameters ◽  
Isolation System ◽  
Railway Bridges ◽  
Design Variables

Based on optimization theories, considering soil-structure interaction and running safety, the optimal design model of the seismic isolation system with lead-rubber bearings (LRB) for a simply supported railway beam bridge is established by using the first order optimization method in ANSYS, which the parameters of the isolation bearing are taken as design variables and the maximum moments at the bottom of bridge piers are taken as objective functions. The optimal calculations are carried out under the excitation of three practical earthquake waves respectively. The research results show that the ratio of the stiffness after yielding to the stiffness before yielding has important effect on the structural seismic responses. Through the optimal analysis of isolated bridge system, the optimal design parameters of isolation bearing can be determined properly, and the seismic forces can be reduced maximally as meeting with the limits of relative displacement between pier top and beam, which provides efficient paths and beneficial references for dynamic optimization design of seismic isolated bridges.

Vulnerability-Based Design of Sliding Concave Bearings for the Seismic Isolation of Steel Storage Tanks

2016 ◽  
Author(s):  
Hoang Nam Phan ◽  
Fabrizio Paolacci ◽  
Silvia Alessandri ◽  
Phuong Hoa Hoang
Keyword(s):  
Liquid Steel ◽  
Seismic Isolation ◽  
Failure Modes ◽  
Fragility Curves ◽  
Time History ◽  
Probability Of Failure ◽  
Design Parameters ◽  
Economic Losses ◽  
Storage Tanks ◽  
Isolation System

Liquid steel storage tanks are strategic structures for industrial facilities and have been widely used both in nuclear and non-nuclear power plants. Typical damage to tanks occurred during past earthquakes such as cracking at the bottom plate, elastic or elastoplastic buckling of the tank wall, failure of the ground anchorage system, and sloshing damage around the roof, etc. Due to their potential and substantial economic losses as well as environmental hazards, implementations of seismic isolation and energy dissipation systems have been recently extended to liquid storage tanks. Although the benefits of seismic isolation systems have been well known in reducing seismic demands of tanks; however, these benefits have been rarely investigated in literature in terms of reduction in the probability of failure. In this paper, A vulnerability-based design approach of a sliding concave bearing system for an existing elevated liquid steel storage tank is presented by evaluating the probability of exceeding specific limit states. Firstly, nonlinear time history analyses of a three-dimensional stick model for the examined case study are performed using a set of ground motion records. Fragility curves of different failure modes of the tank are then obtained by the well-known cloud method. In the following, a seismic isolation system based on concave sliding bearings is proposed. The effectiveness of the isolation system in mitigating the seismic response of the tank is investigated by means of fragility curves. Finally, an optimization of design parameters for sliding concave bearings is determined based on the reduction of the tank vulnerability or the probability of failure.

Numerical Analysis of the Shaft Motion in the Journal Bearing of a Gear Pump

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
R. Castilla ◽  
M. Gutes ◽  
P. J. Gamez-Montero ◽  
E. Codina
Keyword(s):  
Numerical Analysis ◽  
Journal Bearing ◽  
Equation Of Motion ◽  
Metal Contact ◽  
Gear Pump ◽  
Working Pressure ◽  
Stiffness Coefficients ◽  
Metal Metal ◽  
The Mean ◽  
Fifth Order

This paper describes a numerical analysis of the dynamics of the shaft in the journal bearing of a gear pump. The modulus and direction of the load is a function of the relative position of the gears, causing a precession motion around an equilibrium position. The mean load is the function of the working pressure of the gear pump. The numerical analysis presented in this paper combines the equation of motion of the journal-gear set, based on the linearization of the fluid film load, with calculation of the load due to the pressure distribution on the gears. The damping and stiffness coefficients for the motion equation are calculated with the distributions around the shaft of the pressure and its derivatives. These distributions are calculated from the Reynolds equations using an in-house 2D finite element code with quadrangular elements; the equation of motion is solved with a fifth-order Runge–Kutta scheme. The results provide the stabilized position of the shaft for certain conditions, and allow limitation of the working pressure and the angular velocity of the pump in order to minimize, or to avoid, metal-metal contact and consequent wear of material. The results are compared with experiments and previously reported numerical results.

scholarly journals Analysis of an Isolation System with Vertical Spring-viscous Dampers in Horizontal and Vertical Ground Motion

2020 ◽  
Vol 10 (4) ◽  
pp. 1411
Author(s):  
Deog-Jae Hur ◽  
Sung-Chul Hong
Keyword(s):  
Vibration Isolation ◽  
Design Parameters ◽  
Vertical Acceleration ◽  
Isolation System ◽  
Transfer Ratio ◽  
Design Variables ◽  
Conditional Expression ◽  
Vertical Ground ◽  
Reduction Effect ◽  
Isolation Device

This paper proposes a new vibration isolation mounting system, with spherical balls and vertical spring dampers, that provides seismic protection from horizontal and vertical ground excitation. To characterize the system, nonlinear governing equations are derived by considering the kinematics and interaction forces of the structures, and the dynamic characteristics of the design parameters are investigated by numerical analysis. The condition of contact stability for sustaining continuous friction of the isolation device is discussed, along with the design parameters. The vibration transfer characteristics are analyzed for the displacement transfer ratio obtained for the design parameters satisfying the sustainable contact condition, when the base is harmonically excited. The results confirm that the relative motion occurrence satisfies the conditional expression, and a jump in which the transfer ratio suddenly increases at a specific frequency is identified. Finally, design variables that are suitable for the horizontal and vertical acceleration of the El Centro earthquake are set, and a simulation confirms the vibration reduction effect in both the horizontal and vertical motions.

A Study on Semi-Active Control Using Maxwell-Model Variable Damper

2005 ◽  
Author(s):  
Akira Sone ◽  
Arata Masuda ◽  
Daisuke Iba ◽  
Kenichiro Ito
Keyword(s):  
Numerical Analysis ◽  
Active Control ◽  
Seismic Isolation ◽  
Controller Design ◽  
Maxwell Model ◽  
Passive System ◽  
Active System ◽  
Isolation System ◽  
Control Rule ◽  
Model Variable

In recent years, semi-active control has been studied more often in vibration control fields. Semi-active system belongs to a nonlinear system and controller design is not easy. Therefore, the definitive control rule is still not established. This study proposes easy control rule which has only changing the damping coefficient of the seismic isolation system to the maximum and the minimum using the Maxwell-model variable damper and clarifies the influence in numerical analysis which design parameter affect the system further compares the effect with the case of passive system.

On the Harmonic Oscillations for the Motion of a Dynamical System

2017 ◽  
Vol 13 (2) ◽  
pp. 4657-4670
Author(s):  
W. S. Amer
Keyword(s):  
Dynamical System ◽  
Numerical Solutions ◽  
Equation Of Motion ◽  
Parameter Method ◽  
Kutta Method ◽  
Small Parameter Method ◽  
Harmonic Oscillations ◽  
Pivot Point ◽  
Runge Kutta Method ◽  
High Consistency

This work touches two important cases for the motion of a pendulum called Sub and Ultra-harmonic cases. The small parameter method is used to obtain the approximate analytic periodic solutions of the equation of motion when the pivot point of the pendulum moves in an elliptic path. Moreover, the fourth order Runge-Kutta method is used to investigate the numerical solutions of the considered model. The comparison between both the analytical solution and the numerical ones shows high consistency between them.

Isolation Performance of Intelligent Seismic Isolation System Using Air Bearing

2009 ◽  
Author(s):  
Satoshi Fujita ◽  
Keisuke Minagawa ◽  
Mitsuru Miyazaki ◽  
Go Tanaka ◽  
Toshio Omi ◽  
...  
Keyword(s):  
Seismic Isolation ◽  
Seismic Waves ◽  
Three Dimensional ◽  
Vertical Motion ◽  
Air Bearings ◽  
Natural Period ◽  
Isolation System ◽  
Vertical Excitation ◽  
Long Period ◽  
Isolation Performance

This paper describes three-dimensional isolation performance of seismic isolation system using air bearings. Long period seismic waves having predominant period of from a few seconds to a few ten seconds have recently been observed in various earthquakes. Also resonances of high-rise buildings and sloshing of petroleum tanks in consequence of long period seismic waves have been reported. Therefore the isolation systems having very long natural period or no natural period are required. In a previous paper [1], we proposed an isolation system having no natural period by using air bearings. Additionally we have already reported an introduction of the system, and have investigated horizontal motion during earthquake in the previous paper. It was confirmed by horizontal vibration experiment and simulation in the previous paper that the proposed system had good performance of isolation. However vertical motion should be investigated, because vertical motion varies horizontal frictional force. Therefore this paper describes investigation regarding vertical motion of the proposed system by experiment. At first, a vertical excitation test of the system is carried out so as to investigate vertical dynamic property. Then a three-dimensional vibration test using seismic waves is carried out so as to investigate performance of isolation against three-dimensional seismic waves.

Numerical analysis of hip bone replacement design parameters

2021 ◽  
Author(s):  
N. Premkumar ◽  
K. Subhashini ◽  
G. Valarmathi ◽  
Jagadeesh Kumar ◽  
S Meganathan
Keyword(s):  
Numerical Analysis ◽  
Design Parameters ◽  
Bone Replacement ◽  
Replacement Design
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