Investigating coupled train-bridge-bearing system under earthquake and train-induced excitations

2020 ◽  
pp. 1-33
Author(s):  
Hongwei Li ◽  
Daniel Gomez ◽  
Shirley J. Dyke ◽  
Zhao-Dong Xu ◽  
Jun Dai
Keyword(s):  
Fractional Derivatives ◽  
Coupled Model ◽  
Dynamic Interaction ◽  
Dynamic Effects ◽  
Simply Supported ◽  
Dynamic Substructuring ◽  
Bridge Bearing ◽  
Moving Oscillator ◽  
Moving Train ◽  
Bearing System

Abstract The dynamic interaction between a bridge and a moving train has been widely studied. However, there is a significant gap in our understanding of how the presence of isolation bearings influences the dynamic response, especially when an earthquake occurs. Here we formulate a coupled model of a train-bridge-bearing system to examine the bearings' dynamic effects on the system responses. In the analysis, the train is modeled as a moving oscillator, the bridge is a one span simply-supported beam and one isolation bearing is installed under each support of the bridge. A mathematical model using fractional derivatives is used to capture the viscoelastic properties of the bearings. Vertical response is the focus of this investigation. Dynamic substructuring is used in the modeling to efficiently capture the coupled dynamics of the entire system. Illustrative numerical simulations are carried out to examine the effects of the bearings. The results demonstrate that although the presence of bearings typically decreases the bridge seismic responses, there is potential to increase the bridge response induced by the moving train.

Vibration Resonance and Cancellation of Simply Supported Bridges under Moving Train Loads

2014 ◽  
Vol 140 (5) ◽  
pp. 04014015 ◽  
Author(s):  
H. Xia ◽  
H. L. Li ◽  
W. W. Guo ◽  
G. De Roeck
Keyword(s):  
Simply Supported ◽  
Moving Train

On Equivalence of the Moving Mass and Moving Oscillator Problems

2001 ◽  
Author(s):  
Alexander V. Pesterev ◽  
Lawrence A. Bergman ◽  
Chin An Tan ◽  
T.-C. Tsao ◽  
Bingen Yang
Keyword(s):  
High Frequency ◽  
Initial Conditions ◽  
High Frequency Component ◽  
Strict Sense ◽  
Moving Mass ◽  
Spring Stiffness ◽  
Mass Model ◽  
Simply Supported Beam ◽  
Simply Supported ◽  
Moving Oscillator

Abstract Asymptotic behavior of the solution of the moving oscillator problem is examined for large values of the spring stiffness for the general case of nonzero beam initial conditions. In the limit of infinite spring stiffness, the moving oscillator problem for a simply supported beam is shown to be not equivalent in a strict sense to the moving mass problem; i.e., beam displacements obtained by solving the two problems are the same, but the higher-order derivatives of the two solutions are different. In the general case, the force acting on the beam from the oscillator is shown to contain a high-frequency component, which does not vanish, or even grows, when the spring coefficient tends to infinity. The magnitude of this force and its dependence on the oscillator parameters can be estimated by considering the asymptotics of the solution for the initial stage of the oscillator motion. For the case of a simply supported beam, the magnitude of the high-frequency force linearly depends on the oscillator eigenfrequency and velocity. The deficiency of the moving mass model is noted in that it fails to predict stresses in the bridge structure. Results of numerical experiments are presented.

Experimental Study of Dynamic Interaction Between a Steam Generator Tube and an Anti-Vibration Bar

2010 ◽  
Author(s):  
V. Lalonde ◽  
A. Ross ◽  
M. J. Pettigrew ◽  
I. Nowlan
Keyword(s):  
Experimental Study ◽  
Dynamic Behavior ◽  
Steam Generator ◽  
Contact Force ◽  
Dynamic Interaction ◽  
Work Rate ◽  
Fretting Wear ◽  
Steam Generators ◽  
Simply Supported ◽  
Excitation Force

A first experimental work was previously carried out to study the dynamic behavior of a tube simply supported at both ends in interaction with an anti-vibration bar at mid-span. This paper presents modifications to the previous setup with the aim of improving the accuracy of the results. A comparison of the dynamic behavior of the tube is made between both setups. The objective of this experimental study is to characterize the vibration behavior of U-tubes found in steam generators of nuclear power plants. Indeed, two-phase cross-flow in the U-tubes section of steam generators can cause many problems related to vibration. In fact, flow-induced vibration of the U-tubes can cause impacts or rubbing of the tubes against their flat bar supports. Variation of the clearance between the AVB and the U-tubes may lead to ineffective supports. The resulting in-plane and out-of-plane motions of the tubes are causing fretting-wear and impact abrasion. In this study, the clearance between the tube and the AVB, as well as the amplitude, form and frequency of the excitation force are controlled parameters. The first two modes of the tube are studied. The modifications made to the setup lead to significant improvements in the results. The natural frequencies of both setups are compared to theoretical values. The difference between experimental and theoretical frequencies confirms that the new setup better represents the theoretical model of a simply supported tube. The damping of both setups is also compared to values found in literature. The results show that the new setup is more representative of realistic steam generator situations. Compared to the first setup, the displacements of the new setup clearly indicate that the movement of the tube is mostly parallel to the flat bar and in the same direction as the excitation force. The whirling motion of the tube is prevented in the new setup. The accuracy of the contact force as a function of clearance was also improved. The use of more sensitive force sensors helped to reduce the noise level of the contact force. Finally, the dynamic interaction between the tube and the AVB, defined by the fretting wear work-rate, presents a more consistent behavior. The maximum work-rate occurs when the tube is excited around the second mode for clearance between −0.10 and 0.00 mm. Such clearance between the tube and the AVB should then be avoided to minimize fretting damage.

Effects of Boundary Flexibility on the Vibration of a Continuum With a Moving Oscillator

2002 ◽  
Vol 124 (4) ◽  
pp. 552-560 ◽  
Author(s):  
Yonghong Chen ◽  
C. A. Tan ◽  
L. A. Bergman
Keyword(s):  
Shear Force ◽  
Equations Of Motion ◽  
Interaction Force ◽  
Dynamic Interaction ◽  
Spatial And Temporal Distributions ◽  
Expansion Series ◽  
Frequency Components ◽  
Elastically Supported ◽  
Moving Oscillator ◽  
The Continuum

In this paper, the problem of an oscillator traversing an elastically supported continuum is studied. The flexibility in the boundaries of the continuum is modeled by linear, transverse springs. The response of the continuum and the dynamic interaction force between the moving oscillator and the continuum are evaluated by an eigenfunction expansion series. To circumvent convergence difficulties associated with the jump in the shear force due to the moving interaction force, an improved series expansion employing the static Green’s function is derived. The coupled governing equations of motion are solved numerically and results are obtained to examine the effects of the boundary flexibility on the response, the dynamic interaction force, the shear force spatial and temporal distributions, as well as the convergence properties of the expansion series. It is found that high order modal terms contribute significantly to the shear force expansion series in the elastically supported model. The presence of large amplitude and high frequency components in the shear force is critical in understanding the cumulative fatigue failure of the structure. A useful and compact formula estimating the value of the support stiffness above which a boundary may be modeled as simply supported is also derived.

Experimental Study on Moving Train Loads Identification from Bridge Responses

2010 ◽  
Vol 143-144 ◽  
pp. 32-37
Author(s):  
Yi Wang ◽  
Wei Lian Qu
Keyword(s):  
Genetic Algorithm ◽  
Experimental Studies ◽  
Steel Beam ◽  
Beam Model ◽  
Moving Loads ◽  
Simply Supported ◽  
Simulated Annealing Genetic Algorithm ◽  
Bridge Responses ◽  
Moving Train ◽  
Moving Speed

This paper describes a method for multi-axle moving train loads identification based on simulated annealing genetic algorithm by minimizing the errors between the measured displacements and the reconstructed displacements from the identified moving loads. Experimental studies were carried out to investigate the effect of the proposed method on moving loads identification. A simply supported steel beam model and a model train with three carriages were constructed in laboratory. A series of comparative researches for moving loads identification have been conducted. Effects of moving speed and measurement station numbers on the accuracy of the proposed method are investigated. The results show that the proposed method is accurate and feasible for multi-axle moving train loads identification.

Dynamic interaction of the low-to-medium speed maglev train and bridges with different deflection ratios: Experimental and numerical analyses

2020 ◽  
Vol 23 (11) ◽  
pp. 2399-2413 ◽  
Author(s):  
Dangxiong Wang ◽  
Xiaozhen Li ◽  
Yuwen Wang ◽  
Qikai Hu
Keyword(s):  
Interaction Model ◽  
Field Tests ◽  
Dynamic Interaction ◽  
Dynamic Responses ◽  
Vertical Deflection ◽  
Maglev Train ◽  
Simply Supported ◽  
Medium Speed ◽  
The Stability ◽  
Important Design

The deflection ratio of the bridge is an important design parameter influencing the stability of the low-to-medium speed maglev train by affecting the levitation gap. This study focuses on the dynamic interaction of the low-to-medium speed maglev train and bridges with different vertical deflection ratios and investigates the required bridge vertical deflection ratio for the stability of the maglev train. The experimental investigation is carried out first. Then, a numerical dynamic interaction model is established and verified based on the field tests. And then, the influence of the vertical deflection ratio of a 25 m simply supported girder on the dynamic responses is discussed, as well as the bridges with the same deflection ratio but different span lengths. Finally, the maximum deflection ratios for the bridges with different span lengths are proposed and also compared with that of the existing maglev lines around the world. The study shows that when the deflection ratio reaches a certain level, the dynamic responses increase dramatically. The proposed allowable deflection ratios of bridges with different span lengths can not only ensure the smooth running of the train but also reduce the costs.

Nonlinear Dynamic Analysis of an Unsymmetrical Generator-Bearing System

2007 ◽  
Vol 129 (4) ◽  
pp. 448-457 ◽  
Author(s):  
Zhansheng Liu ◽  
Senlin Huang ◽  
Jiexian Su
Keyword(s):  
Dynamic Behavior ◽  
Degrees Of Freedom ◽  
Synthesis Method ◽  
Nonlinear Dynamic Analysis ◽  
Three Dimension ◽  
Dynamic Effects ◽  
Order Model ◽  
Rotor Stiffness ◽  
Rotating Coordinates ◽  
Bearing System

Considering both nonlinear oil film force and unsymmetrical stiffness, this paper presents a mechanical model of a generator-bearing system. The complex mode synthesis method is used to reduce the linear degrees of freedom of the high order model in the rotating coordinates, and one-order modal differential equations are obtained which may not be solved directly by Newmark-β method. To solve this problem, a modified Newmark-β method is presented to investigate dynamic effects of the asymmetry of rotor stiffness, the viscosity of oil, the rotor unbalance and the ratio of length to diameter of bearings. Three-dimension diagrams and unfiltered vibration curves are used as tools to examine the dynamic behavior of the system, and some insights into the dynamic behavior are given. Numerical results show that instability of the system may be improved by modifying these parameters.

Incremental Analysis for Seismic Assessment of Bridge with Functional Bearing System Subjected to Near-Fault Earthquake

2018 ◽  
Vol 19 (01) ◽  
pp. 1940003
Author(s):  
Li-Wei Liu ◽  
Kuang-Yen Liu ◽  
Deng-Gang Huang
Keyword(s):  
Mathematical Formulation ◽  
Design Parameters ◽  
Phase System ◽  
Force Transmission ◽  
Incremental Analysis ◽  
Two Phase ◽  
Near Fault ◽  
Sliding Mechanism ◽  
Bridge Bearing ◽  
Bearing System

A bridge with the functional bearing system, where sticking-sliding mechanism of rubber bearing reduces the force transmission between the substructure and the superstructure, shows viscoelastoplastic behavior. In the present paper, we show a simplified two-degree-of-freedom (2DOF) model for a bridge with the bearing system containing Coulomb’s friction element that displays mechanical behavior including the sticking (viscoelastic) and the sliding (viscoplastic) modes and we arrange its mathematical formulation into a two-phase framework which is a well-implemented form for incremental analysis. Solutions of the two-phase system are explored thoroughly and the exact solution of on-phase under piecewise constant input is obtained. Furthermore, we discuss on–off switching criteria of the bridge bearing system and propose an algorithm, including off-phase (viscoelastic) module, on-phase (viscoplastic) module, pull-back module, admissible condition, and straining condition, to simulate responses of the bridge bearing system. Based on the proposed algorithm, the assessment of the bridge with the functional bearing system which undergoes the near-fault earthquakes was made by investigation of the influence of five kinds of design parameters.

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