Experimental evaluation of accuracy of current practices in analysis and design of railway track sleepers

2008 ◽  
Vol 35 (9) ◽  
pp. 881-893 ◽  
Author(s):  
J. M. Sadeghi
Keyword(s):  
Current Method ◽  
Distribution Patterns ◽  
Field Investigation ◽  
Railway Track ◽  
Wheel Load ◽  
Analysis And Design ◽  
Load Factors ◽  
Track System ◽  
Static And Dynamic Loads ◽  
Made In

This research investigates the accuracy of the assumptions made in the current method of analysis and design of railway track sleepers. This study consists of a comprehensive field investigation into the response of sleepers in a railway track system to static and dynamic loads. In the experiments, several load cells (load gauges) are installed under a rail seat and beneath a B70 concrete sleeper for the purpose of monitoring the response of the sleeper to vertical loads. The dynamic coefficients factor, the ratio of the rail seat load to the wheel load and the pressures between the sleeper and the ballast are measured. The results are used to evaluate the current approaches for the analysis and design of concrete sleepers, in particular those proposed by the Americans (AREMA) and Europeans (UIC). New models are proposed for the calculation of dynamic load factors, correlations between wheel loads and rail seat loads, and load distribution patterns beneath sleepers.

IMPORTANCE OF NONLINEARITY OF TRACK SUPPORT SYSTEM IN MODELING OF RAILWAY TRACK DYNAMICS

2013 ◽  
Vol 13 (01) ◽  
pp. 1350008 ◽  
Author(s):  
J. SADEGHI ◽  
M. FESHARAKI
Keyword(s):  
Support System ◽  
Field Tests ◽  
Field Investigation ◽  
Dynamic Responses ◽  
Railway Track ◽  
Nonlinear Properties ◽  
Railway Tracks ◽  
Track Dynamics ◽  
Track System ◽  
Axle Loads

Attention is drawn to the fact that the recent increase in axle loads, speed and traffic volume in railway tracks, as well as concerns over passengers' riding comfort and safety have resulted in fresh challenges that are needed to be addressed. These challenges can only be successfully tackled with a more accurate modeling of the dynamic behavior of railway tracks. Although a significant amount of research involving mathematical modeling of railway track dynamics has been conducted in the last two decades, the nonlinearity of track support systems has not been given sufficient attention. This paper is concerned with the effect of nonlinearity of the support sub-layers on the dynamic responses of the railway track. To this end, a railway track model that considers the nonlinear properties of the track sub-layers is developed. Then, a field investigation into the dynamic responses of the railway track system under moving trains is conducted. The effect of the nonlinearity properties of the track support system on the track responses is investigated by comparing the results obtained by the numerical model, with or without consideration of track support nonlinearity, with those from the field tests. It is illustrated that consideration of the nonlinear properties of the track support system improves the accuracy of the calculated responses by a factor of three. It is also shown that the train axle loads and track accumulative loading have a significant effect on the nonlinearity of the track support system and, as a result, on the modeling of track responses.

Improvements of conventional methods in railway track analysis and design

2010 ◽  
Vol 37 (5) ◽  
pp. 675-683 ◽  
Author(s):  
J. Sadeghi ◽  
P. Barati
Keyword(s):  
Support System ◽  
Design Method ◽  
Nonlinear Behavior ◽  
Field Investigation ◽  
Railway Track ◽  
Design Parameters ◽  
Element Analysis ◽  
Analysis And Design ◽  
The Impact ◽  
Track Analysis

The aim of this research is to improve the accuracy of conventional railway design methods by addressing the main track substructure parameters omitted in the current track design approach. Nonlinear and discrete properties of the track support system were studied and their influence on the calculation of railway design parameters was measured by conducting a field investigation and using finite element analysis. It was demonstrated that wheel loads and accumulative track loading are the key factors influencing nonlinear behavior of the track support system. Mathematical expressions were developed for the impact of the nonlinearity of the track support system based on the track analysis results, and correction factors were established for rail bending moments and rail deflections calculated by current methods. It was shown that the incorporation of these factors improves the accuracy and reliability of the conventional track design method.

Investigation of free vibrations of voided concrete sleepers in railway track system

2007 ◽  
Vol 221 (4) ◽  
pp. 495-507 ◽  
Author(s):  
S Kaewunruen ◽  
A M Remennikov
Keyword(s):  
Free Vibration ◽  
Free Vibrations ◽  
Vertical Vibration ◽  
Railway Track ◽  
Analysis And Design ◽  
Response Characteristics ◽  
Full Contact ◽  
Track System ◽  
Full Interaction

Concrete railway sleepers in ballasted track are laid on ballast and subgrade supporting systems. Full contact between sleepers and ballast is typically assumed for analysis and design purposes. Often, voids and pockets in the sleeper/ballast contact interface form between sleepers and the ballast underneath that could cause problems to both the sleepers and the track system as a whole. The current paper investigates the effects of ballast voids and pockets on free vibration response characteristics of in situ railway concrete sleepers. Finite-element modelling was employed to develop a dynamic model of the railway track incorporating concrete sleepers. This model includes the dynamic interaction of sleepers and ballast as part of the free vibration analyses of the in situ railway concrete sleepers. Several patterns of voids and pockets underneath railway sleepers were studied. The emphasis was placed on partial and full interaction between sleepers and ballast. The information on the vertical vibration modes provides an important insight into the dynamic response of concrete railway sleepers in different void-and-pocket configurations.

Vision for Mechanistic-Empirical Railway Track System and Component Analysis and Design

2021 ◽  
pp. 036119812110098
Author(s):  
J. Riley Edwards ◽  
Ricardo J. Quirós-Orozco ◽  
Josué César Bastos ◽  
Marcus S. Dersch ◽  
Erol Tutumluer
Keyword(s):  
Structural Reliability ◽  
Failure Modes ◽  
Mechanical Load ◽  
Component Analysis ◽  
Railway Track ◽  
Future Research ◽  
Analysis And Design ◽  
Future Design ◽  
Load Response ◽  
Track System

Many analytical methods and other processes have been developed for the evaluation of railway track and its components, but these have largely been used for analysis. Design is often driven by development projects that do not engage research, resulting in designs that may not be optimized in the context of the broader track structure. This paper proposes a mechanistic-empirical (M-E) analysis and design framework that encourages an understanding of mechanical load-response behavior and comparison of loading demands, and the capacity of the track infrastructure component under study. The approach builds on similar advancements in the field of highway pavement research, including the development and use of the Mechanistic-Empirical Pavement Design Guide (MEPDG). Rail applications present unique economies to a focused M-E design approach, given that loads are concentrated in localized regions and beneath the rails. This paper first reviews prior design and analysis approaches, then presents the essential features of an M-E railway track system and component analysis and design, and, in the end, notes gaps that will require future research before proper implementation of M-E design within rail engineering. The authors also discuss the role of probabilistic design and structural reliability analysis in future design practices. Finally, governing mechanistic failure modes for the track system as well as components and associated life cycle data to achieve full implementation of such an M-E design process are identified and a path forward for implementation is proposed.

scholarly journals AN EX-ANTE ASSESSMENT OF CITY DISTRIBUTION ALTERNATIVES BASED ON MULTI ACTOR MULTI CRITERIA FRAMEWORK

2020 ◽  
Vol 8 (5) ◽  
pp. 4241-4272
Author(s):  
Türkan Müge ÖZBEKLER ◽  
Arzu KARAMAN AKGÜL
Keyword(s):  
Urban Areas ◽  
Noise Pollution ◽  
Distribution Patterns ◽  
Distribution Networks ◽  
Future Research ◽  
Negative Externalities ◽  
Novel Approach ◽  
Load Factors ◽  
Ex Ante ◽  
Urban Consolidation

Recently, urban areas face challenges that result from negative externalities of traditional distribution networks. Especially, city actors increasingly suffer from issues as inefficient load factors in operations, traffic volume on roads, and noise pollution. To overcome these problems, modern city distribution patterns integrated with the consolidation strategy have the potential to provide satisfying solutions. Align with city actors’ expectations, alternatives of consolidation-distribution schemes can offer improvements in both economic, social, and environmental issues. In particular, this study aims at an ex-ante evaluation of city distribution alternatives on the typology of consolidation-distribution schemes ensuring win-win solutions to each city actor. This paper adopts Multi Actor Multi-Criteria Analysis (MAMCA) as a novel approach to evaluating different city actors’ objectives and a set of city distribution alternatives comprehensively. The paper results highlight that micro consolidation centre facilities can be more suitable in response to city actors’ expectations among distribution alternatives to urban consolidation centre and mobile depot. Finally, future research in this topic can focus on evaluating distribution alternatives on a sector basis and marketing types such as B2B and B2C.  

Observations on the Performance of Vibration-Isolated Railway Track

1997 ◽  
Author(s):  
Hugh E. M. Hunt
Keyword(s):  
Travelling Waves ◽  
Surrounding Medium ◽  
Railway Track ◽  
Relative Speed ◽  
Tunnel Wall ◽  
Infinite Beam ◽  
Slab Track ◽  
Torsional Response ◽  
Made In

Abstract Vibration generated by underground railways is difficult to control because of the very limited space available in a tunnel. A popular approach is to use ‘floating slab track’ whereby the rails are fixed to a large concrete foundation separated from the tunnel wall by a resilient material. This paper investigates some of the vibration characteristics of floating slab track from measurements made in situ. These measurements are compared with the theoretical response of an infinite beam on an elastic foundation taking into account the torsional response of the beam. The transmission of vibration through the tunnel wall and into the surrounding medium is discussed with reference to the relative speed of travelling waves and the coincidence frequencies.

Fatigue Analysis of Rail-Head-to-Web Fillet at Bolted Rail Joint Under Various Impact Wheel Load Factors and Support Configurations

2016 ◽  
Author(s):  
Kaijun Zhu ◽  
J. Riley Edwards ◽  
Yu Qian ◽  
Bassem O. Andrawes
Keyword(s):  
Fatigue Life ◽  
Fe Model ◽  
Wheel Load ◽  
Transit Systems ◽  
University Of Illinois ◽  
Rail Head ◽  
Load Factors ◽  
Continuous Welded Rail ◽  
The University ◽  
Better Than

As one of the weakest locations in the track superstructure, the rail joint encounters different types of defects and failures, including rail bolt-hole cracking, rail head-web cracking or separation, broken or missing bolts, and joint bar cracking. The defects and failures are mainly initiated by the discontinuities of both geometric and mechanical properties due to the rail joint, and the high impact loads induced by the discontinuities. Continuous welded rail (CWR) overcomes most disadvantages of the rail joints. However, a large number of rail joints still exist in North American Railroads for a variety of reasons, and bolted joints are especially prevalent in early-built rail transit systems. Cracks are often found to initiate in the area of the first bolt-hole and rail-head-to-web fillet (upper fillet) at the rail end among bolted rail joints, which might cause further defects, such as rail breaks or loss of rail running surface. Previous research conducted at the University of Illinois at Urbana-Champaign (UIUC) has established an elastic static Finite Element (FE) model to study the stress distribution of the bolted rail joint with particular emphasis on rail end bolt-hole and upper fillet areas. Based on the stress calculated from the FE models, this paper focuses on the fatigue performance of upper fillet under different impact wheel load factors and crosstie support configurations. Preliminary results show that the estimated fatigue life of rail end upper fillet decreases as impact factor increases, and that a supported joint performs better than a suspended joint on upper fillet fatigue life.

scholarly journals Study on the Applicability of Dynamic Stability Evaluation Criteria by Comparison of Trackside Measurement Results of Different Track Structures

2020 ◽  
Vol 10 (22) ◽  
pp. 8245
Author(s):  
Kyuhwan Oh ◽  
Jaeik Lee ◽  
Junhyeok Choi ◽  
Yonggul Park
Keyword(s):  
Dynamic Stability ◽  
Evaluation Method ◽  
Evaluation Criteria ◽  
Railway Track ◽  
Stability Evaluation ◽  
Design Specification ◽  
Wheel Load ◽  
Field Instrumentation ◽  
Load Fluctuation ◽  
Concrete Type

Countries such as Korea adopt design codes, evaluation criteria and specifications from standards originating abroad; this leads to a lack of distinction of the separate applications of dynamic stability evaluation parameters between various track structures of different track moduli. This paper discusses the applicability of the dynamic stability evaluation method of railway track structures by assessing 10 different types of railway track sections of a newly constructed railway operation line (5 ballasted and 5 concrete type track structures) by field instrumentation testing. Parameters of track support stiffness (TSS), wheel load fluctuation, derailment coefficient, and rail displacement are measured. The respective results are first compared to the standard criteria (design specification) and comparisons between the different track types are presented as ratios. Findings show that while all of the tracks satisfy the design specification requirements, each track type measurement result varies by a noticeable degree, particularly when comparing between concrete and ballast type track structures. Results of the study demonstrate that using the same dynamic stability evaluation criteria can lead to an incorrect assessment of the track performance evaluation of track structure, and a separate evaluation parameter for ballasted and concrete track structures is required.

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