scholarly journals Vertical Dynamic Analysis of Ballastless Tracks on Train-Track- Bridge System

2020 ◽  
Vol 306 ◽  
pp. 02003
Author(s):  
Haoran Xie ◽  
Bin Yan ◽  
Jie Huang
Keyword(s):  
Track Structure ◽  
Vertical Acceleration ◽  
Train Track ◽  
Steel Spring ◽  
Slab Track ◽  
Ballastless Track ◽  
Track System ◽  
Train Speed ◽  
Track Bridge ◽  
Bridge System

In order to investigate the vertical dynamic response characteristics of train-track-bridge system on CWR (Continunously Welded Rail) under dynamic load of train on HSR (High-Speed Railway) bridge. Based on the principle of vehicle train-track-bridge coupling dynamics, taking the 32m simply supported bridge of a section of Zhengzhou-Xuzhou Passenger Dedicated Line as an example, the finite element software ANSYS and the dynamic analysis software SIMPACK are used for co-simulation, and bridge model of the steel spring floating slab track and the CRTSIII ballastless track (China Railway Track System) considering the shock absorbing steel spring, the limit barricade and the contact characteristics of track structure layers are established. On this basis, in order to study the dynamic response laws of the design of ballastless track structure parameters to the system when the train crosses the bridge and provide the basis for the design and construction, by studying the influence of the speed of train on the bridge, the damage of fasteners and the parameters of track structure on the train-track-bridge system, the displacement of rail, vertical vibration acceleration and wheel-rail force response performance are analyzed. Studies have shown that: At the train speed of 40 km/h, the displacement and acceleration of the rail and track slab in the CRTSIII ballastless track are smaller than the floating slab track structure, but the floating slab track structure has better vibration reduction performance for bridges. The acceleration of rail, track slab and bridge increases obviously with the increase of train speed, the rail structure has the largest increasement. Reducing the stiffness of fasteners could decrease the vertical acceleration response of the steel spring floating slab track system, the ability to absorb shock can be enhanceed by reducing the stiffness of the fastener appropriately. Increasing the density of the floating slab can increase the vertical acceleration of the floating slab and the bridge, thereby decreasing the vibration amplitude of the system.

Analysis of structural stresses of tracks and vehicle dynamic responses in train–track–bridge system with pier settlement

2016 ◽  
Vol 232 (2) ◽  
pp. 421-434 ◽  
Author(s):  
Zhaowei Chen ◽  
Wanming Zhai ◽  
Qiang Yin
Keyword(s):  
High Speed ◽  
Dynamic Responses ◽  
Vertical Acceleration ◽  
Vehicle Dynamic ◽  
Train Track ◽  
Slab Track ◽  
Structural Stresses ◽  
Track Bridge ◽  
Bridge System ◽  
Dynamic Indicators

Pier settlement causes deformation of bridge structures, and further distorts the track structures placed on bridge decks, which may greatly affect the service life of the tracks and safe operation of trains. This study analyzes track stresses and vehicle dynamic responses in train–track–bridge system with pier settlement and determines the pier settlement safe value for high-speed railways with China Railway Track System (CRTS) II slab tracks. First, a detailed train–track–bridge dynamic model is established based on the train–track–bridge dynamic interaction theory. Verified with field experimental results, the model is utilized to calculate the dynamic responses of the vehicle–track–bridge system with different pier settlement values. Finally, the safe value of the pier settlement in the CRTS II slab track railway line is determined according to the limit of the vehicle dynamic indicators and the structural stresses of tracks. The results show that the vertical acceleration of the car body is more sensitive to pier settlement among all the vehicle dynamic indicators. Structural stresses of tracks caused by pier settlement appear at the positions of the pier with settlement and its two adjacent piers. The effect of train loads on the track stresses is much smaller than that of the pier settlement. It is important to adopt the structural stresses of tracks as the evaluation criteria of the pier settlement safe value than the vehicle dynamic indicators. Taking the effects of the bridge pier settlement, the vehicle load, the prestress effect, and the self-weight into consideration, the pier settlement safe value for the high-speed railway lines with the CRTS II slab track is 11.5 mm.

Influence of the track structure on the vertical dynamic interaction analysis of the low-to-medium-speed maglev train-bridge system

2019 ◽  
Vol 22 (14) ◽  
pp. 2937-2950 ◽  
Author(s):  
Dangxiong Wang ◽  
Xiaozhen Li ◽  
Lin Liang ◽  
Xiaowei Qiu
Keyword(s):  
High Frequency ◽  
Local Deformation ◽  
Dynamic Interaction ◽  
Track Structure ◽  
Train Track ◽  
Maglev Train ◽  
Influence Mechanism ◽  
Medium Speed ◽  
Track Bridge ◽  
Bridge System

The low-to-medium-speed maglev train is stably suspended near the rated suspension gap. The suspension force acts directly on the track and is transmitted to the bridge. The maglev track structure is novel, and the influence mechanism of the track structure on the coupled vibration of the maglev train-bridge system is unknown. Therefore, in this study, we propose vertical dynamic interaction models of the low-to-medium-speed maglev train-bridge system and the low-to-medium-speed maglev train-track-bridge system to analyse the influence mechanism of the maglev track structure on the vertical dynamic interaction of the low-to-medium-speed maglev train-bridge system. The vibration characteristics of the F-rail and the influence mechanism of the track structure on the dynamic responses of the bridge are discussed in detail. The study verifies that the local deformation of the F-rail is self-evident and cannot be ignored. In addition, the influence of the F-rail on the dynamic interaction of the maglev train-bridge system is mainly reflected in two aspects: first, the vibration of the bridge in the high-frequency band increases due to the high frequency and intensive local vibration of the F-rail itself. Second, the vibrations of the bridge and the F-rail in the low-frequency band increase due to the periodic irregularities caused by the local deformation of the F-rail. In this study, we consider the vertical dynamic interaction model of the low-to-medium-speed maglev train-track-bridge system.

scholarly journals Mechanical Performance of a Ballastless Track System for the Railway Bridges of High-Speed Lines: Experimental and Numerical Study under Thermal Loading

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2876
Author(s):  
Yingying Zhang ◽  
Lingyu Zhou ◽  
Akim D. Mahunon ◽  
Guangchao Zhang ◽  
Xiusheng Peng ◽  
...  
Keyword(s):  
High Speed ◽  
Thermal Loading ◽  
Mechanical Performance ◽  
Track Structure ◽  
Box Girder ◽  
High Speed Railway ◽  
Ballastless Track ◽  
Track System ◽  
Girder Bridge ◽  
Track Slab

The mechanical performance of China Railway Track System type II (CRTS II) ballastless track suitable for High-Speed Railway (HSR) bridges is investigated in this project by testing a one-quarter-scaled three-span specimen under thermal loading. Stress analysis was performed both experimentally and numerically, via finite-element modeling in the latter case. The results showed that strains in the track slab, in the cement-emulsified asphalt (CA) mortar and in the track bed, increased nonlinearly with the temperature increase. In the longitudinal direction, the zero-displacement section between the track slab and the track bed was close to the 1/8L section of the beam, while the zero-displacement section between the track slab and the box girder bridge was close to the 3/8L section. The maximum values of the relative vertical displacement between the track bed and the bridge structure occurred in the section at three-quarters of the span. Numerical analysis showed that the lower the temperature, the larger the tensile stresses occurring in the different layers of the track structure, whereas the higher the temperature, the higher the relative displacement between the track system and the box girder bridge. Consequently, quantifying the stresses in the various components of the track structure resulting from sudden temperature drops and evaluating the relative displacements between the rails and the track bed resulting from high-temperature are helpful in the design of ballastless track structures for high-speed railway lines.

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.

Influences of Wind Barriers on the Train Running Safety on a Highway-Railway One-Story Bridge

2021 ◽  
pp. 2140009
Author(s):  
Ye Liu ◽  
Yan Han ◽  
Peng Hu ◽  
C. S. Cai ◽  
Xuhui He
Keyword(s):  
Dynamic Responses ◽  
Response Analysis ◽  
Train Track ◽  
Wheel Load ◽  
Wind Barrier ◽  
The Mean ◽  
Wind Pressures ◽  
Track Bridge ◽  
Fluctuating Wind ◽  
Bridge System

In this study, the influences of wind barriers on the aerodynamic characteristics of trains (e.g. a CRH2 train) on a highway-railway one-story bridge were investigated by using wind pressure measurement tests, and a reduction factor of overturning moment coefficients was analyzed for trains under wind barriers. Subsequently, based on a joint simulation employing SIMPACK and ANSYS, a wind–train–track–bridge system coupled vibration model was established, and the safety and comfort indexes of trains on the bridge were studied under different wind barrier parameters. The results show that the mean wind pressures and fluctuating wind pressures on the trains’ surface decrease generally if wind barriers are used. As a result, the dynamic responses of the trains also decrease in the whole process of crossing the bridge. Of particular note, the rate of the wheel load reductions and lateral wheel-axle forces can change from unsafe states to relative safe states due to the wind barriers. The influence of the porosity of the wind barriers on the mean wind pressures and fluctuating wind pressures on the windward sides and near the top corner surfaces of the trains are significantly greater than the influence from the height of the wind barriers. Within a certain range, decreasing the wind barrier porosities and increasing the wind barrier heights will significantly reduce the safety and comfort index values of trains on the bridge. It is found that when the porosity of the wind barrier is 40%, the optimal height of the wind barrier is determined as approximately 3.5[Formula: see text]m. At this height, the trains on the bridges are safer and run more smoothly and comfortably. Besides, through the dynamic response analysis of the wind–train–track–bridge system, it is found that the installation of wind barriers in cases with high wind speeds (30[Formula: see text]m/s) may have an adverse effect on the vertical vibration of the train–track–bridge system.

Non-Stationary Random Vibration Analysis of Railway Bridges Under Moving Heavy-Haul Trains

2018 ◽  
Vol 18 (03) ◽  
pp. 1850035 ◽  
Author(s):  
Zhihui Zhu ◽  
Lidong Wang ◽  
Zhiwu Yu ◽  
Wei Gong ◽  
Yu Bai
Keyword(s):  
Random Vibration ◽  
Vertical Acceleration ◽  
Railway Bridges ◽  
Coupling System ◽  
Ballasted Track ◽  
Heavy Haul ◽  
Train Speed ◽  
Track Irregularity ◽  
Heavy Haul Trains ◽  
Track Bridge

This paper presents a non-stationary random vibration analysis of railway bridges under moving heavy-haul trains by the pseudo-excitation method (PEM) considering the train-track-bridge coupling dynamics. The train and the ballasted track-bridge are modeled by the multibody dynamics and finite element (FE) method, respectively. Based on the linearized wheel-rail interaction model, the equations of motion of the train-ballasted track-bridge coupling system are then derived. Meanwhile, the excitations between the rails and wheels caused by the random track irregularity are transformed into a series of deterministic pseudo-harmonic excitation vectors by the PEM. Then, the random vibration responses of the coupling system are obtained using a step-by-step integration method and the maximum responses are estimated using the 3[Formula: see text] rule for the Gaussian stochastic process. The proposed method is validated by the field measurement data collected from a simply-supported girder bridge (SSB) for heavy-haul trains in China. Finally, the effects of train speed, grade of track irregularity, and train type on the random dynamic behavior of six girder bridges for heavy-haul railways are investigated. The results show that the vertical acceleration and dynamic amplification factor (DAF) of the midspan of the SSB girders are influenced significantly by the train speed and track irregularity. With the increase in the vehicle axle-load, the vertical deflection-to-span ratio ([Formula: see text]) of the girders increases approximately linearly, but the DAF and vertical acceleration fail to show clear trend.

scholarly journals Overview of vibroacoustic isolators used in railway tracks

2018 ◽  
Vol 219 ◽  
pp. 05001
Author(s):  
Cezary Kraśkiewicz ◽  
Wojciech Oleksiewicz ◽  
Monika Płudowska-Zagrajek ◽  
Cezary Lipko
Keyword(s):  
Structure Type ◽  
Basic Material ◽  
Track Structure ◽  
Negative Effects ◽  
Railway Traffic ◽  
Railway Tracks ◽  
Ballastless Track ◽  
Rail Vehicles ◽  
Material Characteristics ◽  
Track System

The paper presents an overview of vibroacoustic isolators used in railway tracks to reduce negative effects from railway traffic. These include single components or their assemblies, with different material characteristics and location in the track structure due to track structure type (ballasted or ballastless track system). The reduction of negative effects relates mainly to the reduction of vibration and structure-borne noise. The practical solutions for railway structures include various components that perform different functions at the same time: vibroacoustic isolation and mechanical function to ensure safe and durable use of rail track (i.e. rail fastening systems, rail supporting structures). The main goals of this paper are systematization and description of basic material characteristics of vibroacoustic isolators applied sufficiently close to the place of vibration generation during the movement of rail vehicles.

scholarly journals Effect of Bridge-Pier Differential Settlement on the Dynamic Response of a High-Speed Railway Train-Track-Bridge System

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Xiaohui Zhang ◽  
Yao Shan ◽  
Xinwen Yang
Keyword(s):  
Dynamic Response ◽  
High Speed ◽  
Tensile Force ◽  
Differential Settlement ◽  
Bridge Pier ◽  
Vertical Acceleration ◽  
Train Track ◽  
Allowable Limit ◽  
High Speed Railway ◽  
Track Bridge

A model based on the theory of train-track-bridge coupling dynamics is built in the article to investigate how high-speed railway bridge pier differential settlement can affect various railway performance-related criteria. The performance of the model compares favorably with that of a 3D finite element model and train-track-bridge numerical model. The analysis of the study demonstrates that all the dynamic response for a span of 24 m is slightly larger than that for a span of 32 m. The wheel unloading rate increases with pier differential settlement for all of the calculation conditions considered, and its maximum value of 0.695 is well below the allowable limit. Meanwhile, the vertical acceleration increases with pier differential settlement and train speed, respectively, and the values for a pier differential settlement of 10 mm and speed of 350 km/h exceed the maximum allowable limit stipulated in the Chinese standards. On this basis, a speed limit for the exceeding pier differential settlement is determined for comfort consideration. Fasteners that had an initial tensile force due to pier differential settlement experience both compressive and tensile forces as the train passes through and are likely to have a lower service life than those which solely experience compressive forces.

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