scholarly journals Random Vibration Analysis of Train Moving over Slab Track on Bridge under Track Irregularities and Earthquakes by Pseudoexcitation Method

2015 ◽  
Vol 2015 ◽  
pp. 1-22 ◽  
Author(s):  
Zhiping Zeng ◽  
Kunteng Zhu ◽  
Xianfeng He ◽  
Wentao Xu ◽  
Lingkun Chen ◽  
...  
Keyword(s):  
High Speed ◽  
Random Vibration ◽  
Equations Of Motion ◽  
Element Model ◽  
Earthquake Intensity ◽  
Dynamic Reliability ◽  
Slab Track ◽  
First Passage Failure ◽  
Operation Stability ◽  
Track Irregularities

This paper investigates the random vibration and the dynamic reliability of operation stability of train moving over slab track on bridge under track irregularities and earthquakes by the pseudoexcitation method (PEM). Each vehicle is modeled by multibody dynamics. The track and bridge is simulated by a rail-slab-girder-pier interaction finite element model. The coupling equations of motion are established based on the wheel-rail interaction relationship. The random excitations of the track irregularities and seismic accelerations are transformed into a series of deterministic pseudoexcitations by PEM. The time-dependent power spectral densities (PSDs) of the random vibration of the system are obtained by step-by-step integration method, and the corresponding dynamic reliability is estimated based on the first-passage failure criterion. A case study is then presented in which a high-speed train moves over a slab track resting on a simply supported girder bridge. The PSD characteristics of the random vibration of the bridge and train are analyzed, the influence of the wheel-rail-bridge interaction models on the random vibration of the bridge and train is discussed, and furthermore the influence of train speed, earthquake intensity, and pier height on the dynamic reliability of train operation stability is studied.

scholarly journals Deformation Law and Control Limit of CRTSIII Slab Track under Subgrade Frost Heave

2021 ◽  
Vol 11 (8) ◽  
pp. 3520
Author(s):  
Xiaopei Cai ◽  
Qian Zhang ◽  
Yanrong Zhang ◽  
Qihao Wang ◽  
Bicheng Luo ◽  
...  
Keyword(s):  
High Speed ◽  
Base Plate ◽  
Element Model ◽  
Middle Part ◽  
Railway Track ◽  
Frost Heave ◽  
Track Structure ◽  
Slab Track ◽  
Plastic Damage ◽  
Track Irregularity

In order to find out the influence of subgrade frost heave on the deformation of track structure and track irregularity of high-speed railways, a nonlinear damage finite element model for China Railway Track System III (CRTSIII) slab track subgrade was established based on the constitutive theory of concrete plastic damage. The analysis of track structure deformation under different subgrade frost heave conditions was focused on, and amplitude the limit of subgrade frost heave was put forward according to the characteristics of interlayer seams. This work is expected to provide guidance for design and construction. Subgrade frost heave was found to cause cosine-type irregularities of rails and the interlayer seams in the track structure, and the displacement in lower foundation mapping to rail surfaces increased. When frost heave occured in the middle part of the track slab, it caused the greatest amount of track irregularity, resulting in a longer and higher seam. Along with the increase in frost heave amplitude, the length of the seam increased linearly whilst its height increased nonlinearly. When the frost heave amplitude reached 35 mm, cracks appeared along the transverse direction of the upper concrete surface on the base plate due to plastic damage; consequently, the base plate started to bend, which reduced interlayer seams. Based on the critical value of track structures’ interlayer seams under different frost heave conditions, four control limits of subgrade frost heave at different levels of frost heave amplitude/wavelength were obtained.

scholarly journals Moving Element Analysis of High-Speed Train-Slab Track System Considering Discrete Rail Pads

2020 ◽  
pp. 2150014
Author(s):  
Tuo Lei ◽  
Jian Dai ◽  
Kok Keng Ang ◽  
Kun Li ◽  
Yi Liu
Keyword(s):  
Coordinate System ◽  
High Speed ◽  
Harmonic Wave ◽  
Equations Of Motion ◽  
Moving Frame ◽  
Iteration Algorithm ◽  
Vehicle Speed ◽  
Element Analysis ◽  
Slab Track ◽  
Track System

This paper presents a study of the dynamic behavior of a coupled train-slab track system considering discrete rail pads. The slab track is modeled as a three-layer Timoshenko beam. The study is carried out using the moving element method (MEM). By introducing a convected coordinate system moving at the same speed as the vehicle, the governing equations of motion of the slab track are formulated in a moving frame-of-reference. By adopting Galerkin’s method, the element stiffness, mass and damping matrices of a truncated slab track in the moving coordinate system are derived. The vehicle is modeled as a multi-body with 10 degrees of freedom. The nonlinear Hertz contact model is used to account for the wheel–rail interaction. The Newmark integration method, in conjunction with a global Newton–Raphson iteration algorithm, is employed to solve the nonlinear dynamic equations of motion of the vehicle–track coupled system. The proposed MEM model of the system is validated through comparison with available results in the literature. Further study is then made to investigate the vehicle–track system accounting for track irregularities modeled as short harmonic wave forms. Results showed that irregularities with short wavelengths have a significant effect on wheel–rail contact force and rail acceleration, and the dynamic response of the track structure does not increase monotonously with the increase of the vehicle speed.

scholarly journals Numerical Simulation of Vertical Random Vibration of Train-Slab Track-Bridge Interaction System by PEM

2014 ◽  
Vol 2014 ◽  
pp. 1-21 ◽  
Author(s):  
Zhi-ping Zeng ◽  
Zhi-wu Yu ◽  
Yan-gang Zhao ◽  
Wen-tao Xu ◽  
Ling-kun Chen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Random Vibration ◽  
Equations Of Motion ◽  
Gaussian Stochastic Process ◽  
Random Load ◽  
Energy Principle ◽  
Slab Track ◽  
Interaction System ◽  
Rail Irregularity ◽  
Track Bridge

The paper describes the numerical simulation of the vertical random vibration of train-slab track-bridge interaction system by means of finite element method and pseudoexcitation method. Each vehicle is modeled as four-wheelset mass-spring-damper system with two-layer suspension systems. The rail, slab, and bridge girder are modeled by three-layer elastic Bernoulli-Euler beams connected with each other by spring and damper elements. The equations of motion for the entire system are derived according to energy principle. By regarding rail irregularity as a series of multipoint, different-phase random excitations, the random load vectors of the equations of motion are obtained by pseudoexcitation method. Taking a nine-span simply supported beam bridge traveled by a train consisting of 8 vehicles as an example, the vertical random vibration responses of the system are investigated. Firstly, the suitable number of discrete frequencies of rail irregularity is obtained by numerical experimentations. Secondly, the reliability and efficiency of pseudoexcitation method are verified through comparison with Monte Carlo method. Thirdly, the random vibration characteristics of train-slab track-bridge interaction system are analyzed by pseudoexcitation method. Finally, applying the 3σrule for Gaussian stochastic process, the maximum responses of train-slab track-bridge interaction system with respect to various train speeds are studied.

scholarly journals Nonlinear Dynamic Behavior of Double-Disk Isotropic Rotor System with Axial Rub-Impact

2011 ◽  
Vol 2-3 ◽  
pp. 678-682
Author(s):  
Y. Zhang ◽  
W.M. Wang ◽  
J.F. Yao
Keyword(s):  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
High Speed ◽  
Element Model ◽  
Rotor System ◽  
Self Healing ◽  
Rotor Bearing ◽  
Nonlinear Dynamic Behavior ◽  
Operation Stability ◽  
Bearing System

In the case of considering the shear effect and gyroscopic effect, a finite element model is developed to study the nonlinear dynamic behavior of a double-disk isotropic rotor- bearing system with axial rub-impact in this paper. The influences of rotational speed and initial phase difference on the operation stability of the rotor-bearing system are discussed. It transpires that the response of the rotor system with axial rub- impact is mainly synchronous periodic motion. The vibration signals of axial rub-impact include such as the synchronous signal and the multiple frequencies, in which the synchronous signal is dominating signal. There is no weakening wave phenomenon in time wave plot. All the results are in reasonable good agreement with those observed in engineering. The results of this paper could provide certain reference for fault diagnosis and self-healing of large high-speed rotating machinery system, thus ensuring the safe operation of the system.

Seismic Response Analysis of High-Speed Railway Bridge Fabricated Round-Ended Piers

2011 ◽  
Vol 243-249 ◽  
pp. 3844-3847 ◽  
Author(s):  
Ling Kun Chen ◽  
Li Zhong Jiang ◽  
Zhi Ping Zeng ◽  
Bo Fu Luo
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Strong Motion ◽  
Element Model ◽  
Theory Of Elasticity ◽  
Response Analysis ◽  
Seismic Load ◽  
Railway Bridge ◽  
Earthquake Intensity ◽  
High Speed Railway

The responses of high-speed railway bridge subjected to seismic load were investigated by numerical simulation, the whole finite element model of the multi-span bridge simply supported bridge was set up, and natural vibration properties of structure were analyzed. According to theory of elasticity and elastic-plasticity, parametric study was conducted to assess the influences of different speeds, strong motion record, pier height and earthquake acceleration on the seismic capability of high-speed bridge subjected to different strength of the earthquake, the finite element soft ware and moment-curvature program were employed to calculate the earthquake responses of bridge. The calculation results show that, with the increase of train speed, pier height and earthquake intensity, the earthquake responses of bridge are increase in general, and the bottom of piers step into states of elastic-plasticity under high-level earthquake, elastic-plastic deformation is larger, the stirrup encryption measures should be carried out.

scholarly journals Seismic Reliability Analysis of Long-Span Cable-stayed Bridges

2015 ◽  
Vol 9 (1) ◽  
pp. 592-597
Author(s):  
Wu Fangwen ◽  
Yang Caofang ◽  
Xue Chengfeng ◽  
Ji Zhengdi
Keyword(s):  
Reliability Analysis ◽  
Cross Sections ◽  
Random Vibration ◽  
Earthquake Resistance ◽  
Seismic Reliability ◽  
Dynamic Reliability ◽  
Vibration Theory ◽  
First Passage Failure ◽  
First Order Second Moment ◽  
Cable Stayed Bridges

Earthquake motion is a random process, and thus, analyzing the seismic responses and dynamic reliability of cable-stayed bridges based on the random vibration theory is important. In this paper, dynamic reliability is investigated under earthquake loads by applying the stochastic vibration theory to the Sutong Yangtze River Highway Bridge. The response statistics are obtained from random vibration analyses, and the dynamic reliability of the normal stress of several key cross sections in the bridge is analyzed using the first-order second-moment method and the first-passage failure theory. The dynamic reliability analysis shows that the reliability index changes with girder section location and meets the design requirements. The analysis shows that the Sutong Bridge has adequate earthquake resistance ability. The structure’s earthquake resistance is appraised to provide an important theoretical reference for improving the seismic resistance design methods.

scholarly journals Probability Density Evolution Algorithm for Stochastic Dynamical Systems Based on Fractional Calculus

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yang Yan ◽  
Xiaohong Yu
Keyword(s):  
Dynamical Systems ◽  
Probability Density ◽  
Random Vibration ◽  
Equations Of Motion ◽  
Coupled System ◽  
Accurate Method ◽  
Computational Accuracy ◽  
Stochastic Dynamical Systems ◽  
Dynamic Reliability ◽  
Representative Points

With the increasing load and speed of trains, the problems caused by various random excitations (such as safety and passenger comfort) have become more prominent and thus arises the necessity to analyze stochastic dynamical systems, which is important in both academic and engineering circles. The existing analysis methods are inadequate in terms of computational accuracy, computational efficiency, and applicability in solving complex problems. For that, a new efficient and accurate method is used in this paper, suitable for linear and nonlinear random vibration analysis of large structures as well as static and dynamic reliability assessment. It is the direct probability integration method, which is extended and applied to the random vibration reliability analysis of dynamical systems. Dynamical models of the dynamic system and coupled system “three-car vehicle-rail-bridge” are established, the time-varying differential equations of motion are derived in detail, and the dynamic response of the system is calculated using the explicit Newmark algorithm. The simulation results show the influence of the number of representative points on the smoothness of the image of the probability density function and the accuracy of the calculation results.

Multibody Systems With Distributed Piezoelectric Actors and Sensors in Flexible Bodies

2001 ◽  
Author(s):  
Michael Rose ◽  
Delf Sachau
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Equations Of Motion ◽  
Element Model ◽  
The Body ◽  
Moving Frame ◽  
Simulation Tools ◽  
Multibody Model ◽  
Multi Body ◽  
The Impact

Abstract Efficiency in high speed mechanism can be further increased by use of lightweight construction. But quite often these structures have the drawback of being susceptible to vibrations. This can be overcome by applying the technology of smart structures. Here distributed actuators and sensors made from piezoceramic (PZT) material are capable to actively reduce the unwelcome vibrations if implemented within a control loop. For the optimal design of such kind of mechanism up-to-date simulation tools have to be developed further. To simulate the dynamic behavior of lightweight structures undergoing large motions the multi-body approach is a suitable tool. The necessary parameters in the equations of motion for the flexible body can be calculated from the output of a finite element code. The large number of variables from the finite element model have to be reduced to only a few generalized coordinates. Therefore a modal reduction is applied in combination with the introduction of a moving frame of reference. Beyond this technique so called active modes are introduced to represent the impact of the active strain by the PZT patches. These active modes combined with natural modes represent the body deformation within the multibody model. As an example the slider/crank mechanism with actively controlled PZT patches on the crank is simulated.

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