The dynamic amplification factors for continuous beam bridges along high-speed railways

In this paper, the dynamic amplification factors (DAFs) of high-speed railway continuous girder bridges are studied. The vehicle-bridge interactions (VBIs) of 13 concrete continuous girder bridges with spans ranging from 48 to 130 m are analyzed, the influences of the train speed, the train marshalling and the bridge fundamental frequency on the DAF are investigated, and the DAF design standard for high-speed railway bridges is discussed. The results indicate that for the continuous beam bridge whose fundamental frequency is less than 3.0 Hz, the maximum DAF is no more than 1.15; while for the bridge examples with a fundamental frequency larger than 3.0 Hz, the maximum DAF reaches 1.25 because the resonance occurs at high train speed. The empirical formulas of the DAFs in the Japan Railway Technical Research Institute (JRTRI) code could provide a conservative estimation of the DAFs of high-speed railway continuous bridges.

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Defect investigation and replacement implementation of bearings for long-span continuous box girder bridges under operating high-speed railway networks: a case study

Structure and Infrastructure Engineering ◽

10.1080/15732479.2020.1867589 ◽

2021 ◽

pp. 1-16

Author(s):

Fengbo Ma ◽

Huile Li ◽

Shitong Hou ◽

Xuecheng Kang ◽

Gang Wu

Keyword(s):

High Speed ◽

Box Girder Bridges ◽

Box Girder ◽

High Speed Railway ◽

Girder Bridges ◽

Long Span ◽

Railway Networks ◽

Defect Investigation

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Notch-based speed trajectory optimisation for high-speed railway automatic train operation

Proceedings of the Institution of Mechanical Engineers Part F Journal of Rail and Rapid Transit ◽

10.1177/09544097211042184 ◽

2021 ◽

pp. 095440972110421

Author(s):

Minling Feng ◽

Chaoxian Wu ◽

Shaofeng Lu ◽

Yihui Wang

Keyword(s):

High Speed ◽

Applied Force ◽

Mixed Integer ◽

High Speed Railway ◽

Train Operation ◽

Train Speed ◽

Automatic Train Operation ◽

The Impact ◽

Trajectory Optimisation

Automatic train operation (ATO) systems are fast becoming one of the key components of the intelligent high-speed railway (HSR). Designing an effective optimal speed trajectory for ATO is critical to guide the high-speed train (HST) to operate with high service quality in a more energy-efficient way. In many advanced HSR systems, the traction/braking systems would provide multiple notches to satisfy the traction/braking demands. This paper modelled the applied force as a controlled variable based on the selection of notch to realise a notch-based train speed trajectory optimisation model to be solved by mixed integer linear programming (MILP). A notch selection model with flexible vertical relaxation was proposed to allow the traction/braking efforts to change dynamically along with the selected notch by introducing a series of binary variables. Two case studies were proposed in this paper where Case study 1 was conducted to investigate the impact of the dynamic notch selection on train operations, and the optimal result indicates that the applied force can be flexibly adjusted corresponding to different notches following a similar operation sequence determined by optimal train control theory. Moreover, in addition to the maximum traction/braking notches and coasting, medium notches with appropriate vertical relaxation would be applied in accordance with the specific traction/braking demands to make the model feasible. In Case study 2, a comprehensive numerical example with the parameters of CRH380AL HST demonstrates the robustness of the model to deal with the varying speed limit and gradient in a real-world scenario. The notch-based model is able to obtain a more realistic optimal strategy containing dynamic notch selection and speed trajectory with an increase (1.622%) in energy consumption by comparing the results of the proposed model and the non-notch model.

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Improvement and Lock Calculation of Electric Switch Machine of Railway Turnout

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.409-410.1496 ◽

2013 ◽

Vol 409-410 ◽

pp. 1496-1501 ◽

Cited By ~ 1

Author(s):

Jing Mang Xu ◽

Ping Wang ◽

Hao Xu

Keyword(s):

Dynamic Model ◽

High Speed ◽

Lateral Stiffness ◽

High Speed Railway ◽

Train Speed ◽

Working Status ◽

Stress And Deformation ◽

Railway Turnout

Electric switch machine locks the crossing rail in the working direction and checks the working status of the crossing. With the increase of train speed, the ZD(J)9 electric switch machine cant satisfy the equipment of high speed railway, This paper studied the optimization; in order to study the lock calculation of nose rail after conversion, a dynamic model is established to research the influence of working status of the crossing. It indicates that for the first traction point, the stress and deformation are mainly affected by scant displacement between nose rail and wing rail; for the second traction point, they are affected by the gap between nose rail and spacer; fastener lateral stiffness doesnt influence the stress status, but the lateral fastener stiffness should not be too small.

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The Minimum Longitudinal Horizontal Linear-Stiffness of Piers of Typical High-Speed Railway’s Layout of Turnout and Bridge

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.255-260.3979 ◽

2011 ◽

Vol 255-260 ◽

pp. 3979-3983

Author(s):

Zhe Liu ◽

Wang Ping

Keyword(s):

Finite Element ◽

High Speed ◽

Element Model ◽

Comprehensive Analysis ◽

Track Structure ◽

Continuous Beam ◽

High Speed Railway ◽

Railway Bridges ◽

Ballast Track ◽

Typical Layout

The values of longitudinal horizontal linear-stiffness of piers are very important parameters in the design of welded turnout on bridge and they can have a great impact on the force and displacement of the turnout. The layout form of turnout and bridge of welded turnout structure system on high-speed railway bridges are various, so the values of longitudinal horizontal linear-stiffness of piers have to be limited in order to insure the strength and stability of track structure on bridges and at the same time meet the requirement of comparative displacement of beam and rail, turnout proper and frog. To make the value-taking easy in the design process, a finite element model for welded turnout-bridge-platform is established in this paper, which is based on the principle of longitudinal interaction of welded turnout on bridges. Directing at three typical layout forms (No.18 single turnout+4×32m continuous beam, single crossover+6×32m continuous beam and typical throat point+4×32m continuous beam) of welded turnout and bridge on ballast track, a research of the relation between the force and displacement of turnout, and the values of longitudinal horizontal linear-stiffness of piers has been carried out. Based on the comprehensive analysis, minimal values of longitudinal horizontal linear-stiffness of piers which are suitable for these three kinds of layout forms, and the values are 1000,800 and 1600 kN/cm·double-line respectively.

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Effects of friction-based fixed bearings on seismic performance of high-speed railway simply supported girder bridges and experimental validation

Advances in Structural Engineering ◽

10.1177/1369433218798120 ◽

2018 ◽

Vol 22 (3) ◽

pp. 687-701 ◽

Cited By ~ 2

Author(s):

Lizhong Jiang ◽

Shanshan Cao ◽

Biao Wei

Keyword(s):

Friction Coefficient ◽

Seismic Performance ◽

High Speed ◽

Dynamic Test ◽

Seismic Damage ◽

Damage State ◽

High Speed Railway ◽

Simply Supported ◽

Girder Bridges ◽

Seismic Force

This study investigated the seismic performance of simply supported girder bridges with a span length of 32 m. Those bridges were a common part in China’s high-speed railway system and used spherical bearings to connect girders and piers. First, a finite element model of the scaled bridge with a geometrical similarity ratio of 1:8 was established by OpenSees. Second, five seismic damage states of fixed bearings and piers were defined based on the deformation failure criterion. Finally, an incremental dynamic analysis and a pseudo-dynamic test were performed to evaluate the effects of friction-based fixed bearings on the seismic response and damage state of bearings and piers. Results show that the sliding of friction-based fixed bearings effectively restricts the force transmitting between piers and girders, and reduces the seismic damage of piers. Those bearings with a small friction coefficient lead to a large relative displacement between piers and girders, while those bearings with a large friction coefficient cause a large seismic force exceeding the yield load of piers. Therefore, an appropriate friction coefficient of friction-based fixed bearing should be determined to achieve an optimal seismic performance of bridge according to the specific conditions of bridge and ground motion inputs.

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