scholarly journals Sequential Track–Bridge Interaction Analysis of Quick-Hardening Track on Bridge Considering Interlayer Friction

2020 ◽  
Vol 10 (15) ◽  
pp. 5066
Author(s):  
Sanghyeon Cho ◽  
Kyoung-Chan Lee ◽  
Seung Yup Jang ◽  
Ilwha Lee ◽  
Wonseok Chung
Keyword(s):  
Sequential Analysis ◽  
Interaction Analysis ◽  
Frictional Coefficient ◽  
Additional Stress ◽  
Low Friction ◽  
Running Safety ◽  
Ballast Track ◽  
Longitudinal Resistance ◽  
Longitudinal Slip ◽  
Track Bridge

A quick-hardening track (QHT) was developed by injecting quick-hardening mortar into an existing ballast track to rapidly substitute the ballast track with a slab track, thereby improving maintainability and running safety. QHT tracks on a bridge undergo track–bridge interactions similar to other track systems. This paper presents a model to analyze the interaction between the QHT and the bridge. This model considers the longitudinal resistances of rail fasteners and anchors, as well as the interlayer friction between the track and the bridge. A sequential analysis method was applied to systematically consider such effects, revealing that rail additional stress will be high if the track slips over the bridge for a very low frictional coefficient of 0.1. Furthermore, a track segment without an anchor can slip under train traction load when the frictional coefficient is 0.3 or lower. For low friction cases, low-speed operation is advised to prevent the accumulation of the resulting longitudinal slip displacements of the track. An anchor should be installed immediately after the quick-hardening mortar provides sufficient bearing strength to the anchors. The proposed sequential analysis is useful for determining the critical friction coefficient and appropriate longitudinal resistance of a rail fastener, as well as for verifying track safety.

Analysis of Longitudinal Resistance Characteristics according to the Vertical Loads of Ballast Track on a Bridge

2019 ◽  
Vol 7 (2) ◽  
pp. 239-244
Author(s):  
Geon Soo Shin ◽  
Jong Chan Park ◽  
Jyung Hwan Min ◽  
Kyung Min Yun ◽  
Nam Hyoung Lim ◽  
...  
Keyword(s):  
Ballast Track ◽  
Longitudinal Resistance

Numerical Analysis of Bridge Expansion-Induced Rail Deformation of Ballast Truck

2014 ◽  
Vol 580-583 ◽  
pp. 3208-3214 ◽  
Author(s):  
Zhen Wei Xiong ◽  
Xin Ling Liang ◽  
Xian Xing Dai ◽  
Ping Wang
Keyword(s):  
Granular Flow ◽  
Element Model ◽  
Discrete Element Model ◽  
Board Structure ◽  
Vertical Deformation ◽  
Two Dimensional ◽  
Running Safety ◽  
Bridge Plate ◽  
Ballast Track ◽  
The Relationship

when the ballast track stretch with the bridge, ballast which is near expansion joint will move confusedly. As a result, rail produced vertical deformation. The deformation will affect the running safety and comfortability of train. At present, there are two kinds of treatments which are cover board structure and baffle structure to deal ballast’s movement. Aiming at the different modes of stretching when the two kinds of structures and different arrangement condition of bridge plate are applied, the rail-sleeper-ballast discrete element model is developed by the method of two-dimensional granular flow. The relationship between rail deformation and bridge expansion is analyzed on the foundation of the model. Results show as flows: when bridge extends or shortens, rail always produced upwarp deformation. Bridge plate should arrange asymmetrically. Like this, the rail deformation decrease by 40%. And adopting the baffle structure can effectively reduce the influence of bridge expansion in ballast truck.

Suggestion for allowable additional compressive stress based on track conditions

2017 ◽  
Vol 232 (5) ◽  
pp. 1309-1325 ◽  
Author(s):  
Kyung-Min Yun ◽  
Beom-Ho Park ◽  
Hyun-Ung Bae ◽  
Nam-Hyoung Lim
Keyword(s):  
Compressive Stress ◽  
Structural Characteristics ◽  
Three Dimensional ◽  
Additional Stress ◽  
Analysis Model ◽  
Temperature Changes ◽  
Lateral Resistance ◽  
Ballasted Track ◽  
Continuous Welded Rail ◽  
Track Bridge

A continuous welded rail has immovable zones due to its structural characteristics. In an immovable zone, thermal expansion and contraction of rails are restricted when the temperature changes, thereby causing excessive axial force on the rail. When the immovable zone of the continuous welded rail is located on a bridge, additional stress and displacement occur through track–bridge interactions. Additional stress and displacement of the rail compared to the embankment area are restricted when constructing the bridge under the continuous welded rail track to prevent problems with the track–bridge interaction according to UIC 774-3R and Euro codes. According to the various codes, the maximum allowable additional compressive stress is 72 MPa, with the conditions of a curve with a radius (R) ≥ 1500 m, UIC 60 continuous welded rail (tensile strength of at least 900 MPa), ballasted track with concrete sleepers and 30 cm of deep for a well-consolidated ballast. However, the lateral resistance that has the greatest effect on track stability can depend on the conditions mentioned above. Therefore, an additional review of various track conditions is required. In this paper, an evaluation of the current criteria was performed using the minimum buckling strength calculation formula, and the allowable additional stress on the rail suggested by codes could only be used on tracks with a large lateral resistance above 18 kN/m/track. Thus, a three-dimensional nonlinear analysis model was developed and analyzed to calculate the allowable additional compressive stress considering various track conditions. According to the results of the analysis, the allowable additional compressive stress was reduced with a comparatively small lateral resistance. The freedom of design can be enhanced with respect to the parameters of various track and bridge conditions using this model.

Dynamic analysis of coupled train–track–bridge system subjected to debris flow impact

2018 ◽  
Vol 22 (4) ◽  
pp. 919-934 ◽  
Author(s):  
Xun Zhang ◽  
Zhipeng Wen ◽  
Wensu Chen ◽  
Xiyang Wang ◽  
Yan Zhu
Keyword(s):  
Debris Flow ◽  
Dynamic Analysis ◽  
High Speed ◽  
Impact Load ◽  
Dynamic Responses ◽  
Train Track ◽  
Running Safety ◽  
Track Bridge ◽  
Safety Indices ◽  
Bridge System

With the increasing popularity of high-speed railway, more and more bridges are being constructed in Western China where debris flows are very common. A debris flow with moderate intensity may endanger a high-speed train traveling on a bridge, since its direct impact leads to adverse dynamic responses of the bridge and the track structure. In order to address this issue, a dynamic analysis model is established for studying vibrations of coupled train–track–bridge system subjected to debris flow impact, in which a model of debris flow impact load in time domain is proposed and applied on bridge piers as external excitation. In addition, a six-span simply supported box girder bridge is considered as a case study. The dynamic responses of the bridge and the running safety indices such as derailment factor, offload factor, and lateral wheel–rail force of the train are investigated. Some influencing factors are then discussed based on parametric studies. The results show that both bridge responses and running safety indices are greatly amplified due to debris flow impact loads as compared with that without debris flow impact. With respect to the debris flow impact load, the boulder collision has a more negative impact on the dynamic responses of the bridge and train than the dynamic slurry pressure. Both the debris flow impact intensity and train speed determine the running safety indices, and the debris flow occurrence time should be also carefully considered to investigate the worst scenario.

Mapping relationship between dynamic responses of high-speed trains and additional bridge deformations

2020 ◽  
pp. 107754632093689
Author(s):  
Hongye Gou ◽  
Chang Liu ◽  
Hui Hua ◽  
Yi Bao ◽  
Qianhui Pu
Keyword(s):  
High Speed ◽  
Coupled Model ◽  
Dynamic Responses ◽  
High Speed Railway ◽  
Railway Bridges ◽  
Running Safety ◽  
High Speed Trains ◽  
Track Bridge ◽  
The Relationship ◽  
Track Deformation

Deformations of high-speed railways accumulate over time and affect the geometry of the track, thus affecting the running safety of trains. This article proposes a new method to map the relationship between dynamic responses of high-speed trains and additional bridge deformations. A train–track–bridge coupled model is established to determine relationship between the dynamic responses (e.g. accelerations and wheel–rail forces) of the high-speed trains and the track deformations caused by bridge pier settlement, girder end rotation, and girder camber. The dynamic responses are correlated with the track deformation. The mapping relationship between bridge deformations and running safety of trains is determined. To satisfy the requirements of safety and riding comfort, the suggested upper thresholds of pier settlement, girder end rotation, and girder camber are 22.6 mm, 0.92‰ rad, and 17.2 mm, respectively. This study provides a method that is convenient for engineers in evaluation and maintenance of high-speed railway bridges.

Rail-Structure Interaction Analysis of Sliding Slab Track on Bridge

2015 ◽  
Author(s):  
Kyoung-Chan Lee ◽  
Seung Yup Jang ◽  
Dong-Ki Jung ◽  
Hyung-Kyoon Byun ◽  
Hyo-Ki Park ◽  
...  
Keyword(s):  
Interaction Analysis ◽  
Span Length ◽  
Bridge Structure ◽  
Structure Interaction ◽  
Slab Track ◽  
Axial Forces ◽  
Continuous Welded Rail ◽  
Rail Structure ◽  
Track Bridge ◽  
Sliding Slab

Continuous welded rail (CWR) on a bridge structure typically experiences a large amount of additional longitudinal axial forces due to longitudinal rail-structure (or track-bridge) interaction under temperature change and train vertical and traction/braking load effect. In order to reduce the additional axial forces, a special type of fastener, such as zero longitudinal restraint (ZLR) and reduced longitudinal restraint (RLR) or rail expansion joint (REJ) should be applied. Sliding slab track system is developed to reduce the effect of rail-structure interaction through the application of a low-frictional sliding layer between slab track and bridge structure. This study presents a track-bridge interaction analysis of the sliding slab track and compares them with conventional fixed slab track on bridges. Various types of span length and longitudinal profiles of bridges are considered in the analysis, which also include multiple continuous spans and extra-dosed bridges. The analysis found that the sliding slab track can reduce the additional axial forces of the continuous welded rail from 80% to 90%, and the difference is more significant for long and continuous span bridge. By the application of the sliding slab track, the use of any other special type of rail fasteners or REJ can be avoided. In addition, span length will not be restricted by the rail-structure interaction effect in planning the railway bridge layout. Continuous span bridge has been usually avoided for railway bridges, but it is preferred for the application of the sliding slab track because the interaction effect can mostly be removed. A continuous span bridge usually has an economical cross-section for the bridge girder, pier and foundation and better dynamic characteristics compared to simple span bridge, and its application eventually will reduce the construction cost of the railway infrastructure.

Effects of the highway live load on the additional forces of the continuously welded rails of a long-span suspension bridge

2021 ◽  
pp. 095440972110619
Author(s):  
Xiangdong Yu ◽  
Nengyu Cheng ◽  
Haiquan Jing
Keyword(s):  
High Speed ◽  
Suspension Bridge ◽  
Additional Stress ◽  
Live Load ◽  
Analysis Model ◽  
Maximum Displacement ◽  
Obvious Effect ◽  
Long Span Bridges ◽  
Long Span ◽  
Track Bridge

High-speed running trains have higher regularity requirements for rail tracks. The track-bridge interaction of long-span bridges for high-speed railways has become a key factor for engineers and researchers in the last decade. However, studies on the track-bridge interaction of long-span bridges are rare because the bridges constructed for high-speed railways are mainly short- or moderate-span bridges, and the effects of the highway live load on the additional forces of continuously welded rails (CWRs) have not been reported. In the present study, the effects of the highway live load on the additional forces of a CWR of a long-span suspension bridge are investigated through numerical simulations. A track-bridge spatial analysis model was established using the principle of the double-layer spring model and the bilinear resistance model. The additional stress and displacement of the rail are calculated, and the effects of the highway live load are analyzed and compared with those without a highway live load. The results show that the highway live load has an obvious effect on the additional forces of a CWR. Under a temperature force, the highway live load increases the maximum tensile stress and compressive stress by 10 and 13%, respectively. Under a bending force, the highway live load increases the maximum compressive rail stress and maximum displacement by 50 and 54%, respectively. Under a rail breaking force, when the highway live load is taken into consideration, the rail displacement at both sides of the broken rail varies by 50 and 42%, respectively. The highway live load must be taken into consideration when calculating the additional forces of rails on highway-railway long-span bridges.

Modification of the Conventional Method for the Track-Bridge Interaction

2012 ◽  
Vol 204-208 ◽  
pp. 1988-1991 ◽  
Author(s):  
Kyung Min Yun ◽  
Jin Yu Choi ◽  
Chin Ok Lee ◽  
Nam Hyoung Lim
Keyword(s):  
Conventional Method ◽  
Bridge Deck ◽  
Separate Analysis ◽  
Design Codes ◽  
Loading History ◽  
Longitudinal Stress ◽  
Modified Method ◽  
Highly Nonlinear ◽  
Longitudinal Resistance ◽  
Track Bridge

In order to obtain the interaction behavior between the track and the bridge, the various design codes adopted generally the recommendations of the UIC leaflet. The maximum longitudinal stress (force) in the rail can be calculated by the linear combination of the results obtained by the separate analysis of three elementary important loads. This conventional method completely neglects the influence of the loading history, and may have some error because of the behavior of the longitudinal resistance connecting the rail and the bridge-deck is under the highly nonlinear. In this study, the algorithm for the modified method considering the sequential nonlinear loading combination and the effect of the loading history is proposed. The results from the application of the modified method are compared with the results obtained from the conventional method.

scholarly journals Evolution of Longitudinal Resistance Performance of Granular Ballast Track with Durable Dynamic Reciprocated Changes

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Jieling Xiao ◽  
Hao Liu ◽  
Ping Wang ◽  
Ganzhong Liu ◽  
Jingmang Xu ◽  
...  
Keyword(s):  
Dynamic Change ◽  
Cyclic Softening ◽  
Service Performance ◽  
Cyclic Process ◽  
Test Model ◽  
Test Analysis ◽  
Dynamic Disturbance ◽  
Loading System ◽  
Ballast Track ◽  
Longitudinal Resistance

A full-scale test model with a distinct loading system is developed to analyze the dynamic change process of ballast beds under cyclic longitudinal reciprocated loading. The test analysis methodology accounts for the service performance, longitudinal resistances, and evolution trend of ballast beds under long-term loading. The analysis shows that the ballast resistance-displacement curves under cyclic loading are a set of closed hysteretic curves, indicating obvious energy consumption. In particular, a granular ballast bed is subject to cyclic softening during the cyclic process and the ballast longitudinal resistances degenerate obviously. More particularly, the cyclic softening of a granular ballast bed is dependent on the dynamic disturbance amplitude—the higher the dynamic disturbance amplitude, the more severe the cyclic softening will become. Moreover, this methodology contributes to forming a foundation for an in-depth understanding of the dynamic service performance of ballast CWR tracks and of the stress deformation mechanism of continuously welded rail tracks.

Sign in / Sign up

Export Citation Format

Share Document