scholarly journals Reduction of Vehicle-Induced Vibration of Railway Bridges due to Distribution of Axle Loads through Track

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Zhibin Jin ◽  
Bo Huang ◽  
Juanjuan Ren ◽  
Shiling Pei
Keyword(s):  
Moving Load ◽  
Point Load ◽  
Track Structure ◽  
Spreading Effect ◽  
Railway Bridges ◽  
Load Model ◽  
Numerical Studies ◽  
Reduction Coefficient ◽  
Axle Loads ◽  
Bridge Responses

Short span railway bridges are prone to resonate caused by dynamic train axle loads, which were usually modeled as moving point loads on the bridge in many numerical studies. In reality, the axle weight of the train is a spread load for the bridge deck because of the transfer of the track structure. Previous numerical studies indicated that the spread axle load distributed through the track structure significantly reduces bridge responses compared to the point load model. In this study, the reduction effect is investigated analytically by solving the moving load problem for both the point load and the spread load cases. The analytical solution reveals that bridge responses from the spread load model can be obtained by filtering bridge responses from the point load model. The filter function is exactly the Fourier transform (FT) of the load spreading function. Based on this relationship, a reduction coefficient reflecting the load spreading effect on bridge responses is derived. Through numerical examples, the accuracy of this proposed reduction coefficient is validated not only for the moving load models but also for vehicle-bridge interaction (VBI) problems.

The Calculation of the Supporting Stress of Track Plate in Ballastless High-Speed Rail Structure

2011 ◽  
Vol 97-98 ◽  
pp. 3-9
Author(s):  
Yang Wang ◽  
Quan Mei Gong ◽  
Mei Fang Li
Keyword(s):  
Stress Distribution ◽  
High Speed ◽  
Design Theory ◽  
Moving Load ◽  
Structure Design ◽  
Track Structure ◽  
Beam Model ◽  
High Speed Rail ◽  
Slab Track ◽  
Ballastless Track

The slab track is a new sort of track structure, which has been widely used in high-speed rail and special line for passenger. However, the ballastless track structure design theory is still not perfect and can not meet the requirements of current high-speed rail and passenger line ballastless track. In this paper, composite beam method is used to calculate the deflection of the track plate and in this way the vertical supporting stress distribution of the track plate can be gotten which set a basis for the follow-up study of the dynamic stress distribution in the subgrade. Slab track plate’s bearing stress under moving load is analyzed through Matlab program. By calculation and analysis, it is found that the deflection of track plate and the rail in the double-point-supported finite beam model refers to the rate of spring coefficient of the fastener and the mortar.The supporting stress of the rail plate is inversely proportional to the supporting stress of the rail. The two boundary conditions of that model ,namely, setting the end of the model in the seams of the track plate or not , have little effect on the results. We can use the supporting stress of the track plates on state 1to get the distribution of the supporting stress in the track plate when bogies pass. Also, when the dynamic load magnification factor is 1.2, the track plate supporting stress of CRST I & CRST II-plate non-ballasted structure is around 40kPa.

scholarly journals Structural Pounding Detection by Using Wavelet Scalogram

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Shutao Xing ◽  
Marvin W. Halling ◽  
Qingli Meng
Keyword(s):  
Experimental Studies ◽  
Shake Table Tests ◽  
Rigid Barrier ◽  
Single Degree Of Freedom ◽  
Structural Pounding ◽  
Numerical Studies ◽  
Bridge Model ◽  
On Line ◽  
Potential Damage ◽  
Bridge Responses

Structural pounding can cause considerable damage and even lead to collapse of structures. Most research focuses on modeling, parameter investigation, and mitigation approaches. With the development of structural health monitoring, the on-line detection of pounding becomes possible. The detection of pounding can provide useful information of potential damage of structures. This paper proposed using wavelet scalograms of dynamic response to detect pounding and examined the feasibility of this method. Numerical investigations were performed on a pounding system that consisted of a damped single-degree-of-freedom (SDOF) structure and a rigid barrier. Hertz contact model was used to simulate pounding behavior. The responses and pounding forces of the system under harmonic and earthquake excitations were numerically solved. The wavelet scalograms of acceleration responses were used to identify poundings. It was found that the scalograms can indicate the occurrence of pounding and occurrence time very well. The severity of the poundings was also approximately estimated. Experimental studies were carried out, in which shake table tests were conducted on a bridge model that underwent pounding between its different components during ground motion excitation. The wavelet scalograms of the bridge responses indicated pounding occurrence quite well. Hence the conclusions from the numerical studies were verified experimentally.

scholarly journals Track Dynamic Response At Low Frequencies – Dominant Frequencies

2015 ◽  
Vol 15 (2) ◽  
Author(s):  
Milan Moravčík ◽  
Martin Moravčík
Keyword(s):  
Dynamic Response ◽  
Moving Load ◽  
Low Frequency ◽  
Track Structure ◽  
Dynamic Effects ◽  
Low Frequencies ◽  
Frequency Area ◽  
Dominant Frequencies ◽  
40 Hz

Abstract The paper is devoted dynamic effects in the track structure - the quasi-static excitation due to moving load, as the important source for the response of track components in the low frequency area (0 Hz < f < 40 Hz). The low-frequency track (the rail) response is associated with periodicity of wheel sets, bogies, and carriages of passage trains, The periodicity of track loading is determined by so called dominant frequencies f(d) at a position x of the track.

scholarly journals The Effects of Moving Load on the Hydroelastic Response of a Very Large Floating Structure

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Le Zhu ◽  
Fei Shao ◽  
Qian Xu ◽  
Yonggang Sun ◽  
Qingna Ma
Keyword(s):  
Moving Load ◽  
Fluid Motion ◽  
Elastic Beam ◽  
Point Load ◽  
Floating Structure ◽  
Very Large Floating Structure ◽  
External Point ◽  
The Fourier Transform ◽  
The Time Domain ◽  
Hydroelastic Response

The hydroelastic response of a very large floating structure in regular waves suffering an external moving point load is considered. The linearized velocity potential theory is adopted to describe the fluid flow. To take into account the coupled effects of the structure deformation and fluid motion, the structure is divided into multiple segments and connected by an elastic beam. Then through adding a stiffness matrix arising from the elastic beam into the multiple bodies coupled motion equations, the hydroelastic response is considered. By applying the Fourier transform to the obtained frequency domain coefficients, the motion equation is transformed into the time domain and the external point load is further considered. The accuracy and effectiveness of the proposed method are verified through the comparison with experimental results. Finally, extensive results are provided, and the effects of the moving point load on the hydroelastic response of the very large floating structure are investigated in detail.

scholarly journals Dynamic Behavior of a Bidirectional Functionally Graded Sandwich Beam under Nonuniform Motion of a Moving Load

2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Dinh Kien Nguyen ◽  
An Ninh Thi Vu ◽  
Ngoc Anh Thi Le ◽  
Vu Nam Pham
Keyword(s):  
Dynamic Response ◽  
Dynamic Behavior ◽  
Moving Load ◽  
Sandwich Beam ◽  
Point Load ◽  
Functionally Graded ◽  
Beam Model ◽  
Material Distribution ◽  
Aspect Ratios ◽  
Nonuniform Motion

A bidirectional functionally graded Sandwich (BFGSW) beam model made from three distinct materials is proposed and its dynamic behavior due to nonuniform motion of a moving point load is investigated for the first time. The beam consists of three layers, a homogeneous core, and two functionally graded face sheets with material properties varying in both the thickness and longitudinal directions by power gradation laws. Based on the first-order shear deformation beam theory, a finite beam element is derived and employed in computing dynamic response of the beam. The element which used the shear correction factor is simple with the stiffness and mass matrices evaluated analytically. The numerical result reveals that the material distribution plays an important role in the dynamic response of the beam, and the beam can be designed to meet the desired dynamic magnification factor by appropriately choosing the material grading indexes. A parametric study is carried out to highlight the effects of the material distribution, the beam layer thickness and aspect ratios, and the moving load speed on the dynamic characteristics. The influence of acceleration and deceleration of the moving load on the dynamic behavior of the beam is also examined and highlighted.

Assessment of Corrosion Effects on Railway Bridges in the Middle Area of Vietnam Using Multibody Dynamics Approach

2020 ◽  
Vol 897 ◽  
pp. 3-11
Author(s):  
My Pham ◽  
Cong Thuat Dang ◽  
Chinh Van Nguyen
Keyword(s):  
Numerical Model ◽  
Multibody Dynamics ◽  
Dynamic Testing ◽  
Load Capacity ◽  
Moving Load ◽  
Localized Corrosion ◽  
Steel Bridge ◽  
Actual Measurement ◽  
Railway Bridges ◽  
Bridge Model

A railway bridge over several decades will be degraded due to localized corrosion. As a result, the load capacity of the bridge decreases, especially under the live load caused by trains. This paper examines the residual load capacity of a bridge deteriorated by localized corrosion by using the multibody dynamics approach. This approach allows an accurate description of the interaction between trains and bridges. At the same time, it allows the formation of corrosion marks on each structural member of the bridge in a numerical model precisely based on actual measured data. In order to describe accurately the remaining load of the bridge under the moving load of the train, a dynamic testing and finite element modeling of a steel bridge are conducted and compared. At the same time, the results are also compared with the simulation results of the bridge model before being corroded. In addition, the paper also tests the reliability of the numerical model for assessments of similar bridges without actual measurement results that are costly and time-consuming.

Field Verification of Moving Load Model for Pavement Response

1996 ◽  
Vol 1540 (1) ◽  
pp. 125-131 ◽  
Author(s):  
Raj Siddharthan ◽  
Jian Yao ◽  
Peter E. Sebaaly
Keyword(s):  
Moving Load ◽  
Field Tests ◽  
Field Testing ◽  
Material Behavior ◽  
Vehicle Speed ◽  
Strain Response ◽  
State University ◽  
Load Model ◽  
Pavement Response ◽  
The Difference

A validation study undertaken to verify the predictive capability of a recently developed moving load model to predict pavement response is described. The full-scale field-measured responses of longitudinal strain at the bottom of the asphalt concrete (AC) layer were used in the verification. The field testing program, in which the strain responses induced by a semitrailer truck were measured as a function of vehicle speed, was carried out at the Pennsylvania State University test track. The material behavior of the AC layer, which was assumed to be viscoelastic, was deduced from the laboratory behavior of the AC and from the backcalculated AC modulus from falling-weight deflectometer data. The unbound material layer properties were assumed to be elastic. The moving load model reproduced many important general observations made from the field tests, such as the existence of a complex interaction in the case of a tandem axle configuration and the strong influence of vehicle speed on the strain response. Good agreement exists between the predictions made by the model for the strain response for single and tandem axle configurations under different loading and vehicle speeds and those measured in the field. The difference is less than 14 percent, thus verifying the applicability of the moving load model to predict pavement response.

Viscoelastic response of a floating ice plate to a steadily moving load

1988 ◽  
Vol 196 ◽  
pp. 409-430 ◽  
Author(s):  
R. J. Hosking ◽  
A. D. Sneyd ◽  
D. W. Waugh
Keyword(s):  
Asymptotic Theory ◽  
Moving Load ◽  
Memory Function ◽  
Point Load ◽  
Flexural Waves ◽  
Moving Vehicle ◽  
Viscoelastic Theory ◽  
Subcritical Speed ◽  
Moving Line ◽  
Two Parameter

Viscoelastic theory is used to describe the response of a floating ice sheet to a moving vehicle. We adopt a two-parameter memory function to describe the behaviour of the ice, subjected to a steadily moving line or point load. The viscoelastic dissipation produces an asymmetric quasi-static response at subcritical speed, renders a finite response at the critical speed, and damps the shorter leading waves rather more severely than the longer trailing waves at supercritical speed. We extend earlier asymptotic theory to consider the anisotropic damping of the flexural waves. There is enhanced agreement between theory and experiment.

Moving Load on a Fluid-Solid Interface: Subsonic and Intersonic Regimes

1973 ◽  
Vol 40 (4) ◽  
pp. 885-890 ◽  
Author(s):  
T. C. Kennedy ◽  
G. Herrmann
Keyword(s):  
Steady State ◽  
Moving Load ◽  
Point Load ◽  
Numerical Results ◽  
Plane Interface ◽  
Steady State Response ◽  
State Response ◽  
Solid Interface

The steady-state response of a semi-infinite solid, with an overlying semi-infinite fluid, subjected at the plane interface to a moving point load is determined for subsonic and intersonic load velocities. Some numerical results for the displacements at the interface are presented and compared to the results obtained in the absence of the fluid.

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