scholarly journals Track Modulus Assessment of Engineered Interspersed Concrete Sleepers in Ballasted Track

2020 ◽  
Vol 11 (1) ◽  
pp. 261
Author(s):  
Arthur de Oliveira Lima ◽  
Marcus S. Dersch ◽  
Jaeik Lee ◽  
J. Riley Edwards
Keyword(s):  
Theoretical Calculations ◽  
Single Point ◽  
Point Load ◽  
Railway Track ◽  
Optimized Design ◽  
Wheel Load ◽  
Field Instrumentation ◽  
Stiffness Properties ◽  
Materials Used ◽  
Track Modulus

Ballasted railway track is typically constructed using sleepers that are manufactured from a common material type within a given length of track. Timber and concrete are the two most common sleeper materials used internationally. Evidence from historical installations of interspersed concrete sleepers in timber sleeper track in North America has indicated inadequate performance, due largely to the heterogeneity in stiffnesses among sleepers. Theoretical calculations reveal that interspersed installation, assuming rigid concrete sleepers and supports, can result in rail seat forces more than five times as large as the force supported by the adjacent timber sleepers. Recently, engineered interspersed concrete (EIC) sleepers were developed using an optimized design and additional layers of resiliency to replace timber sleepers that have reached the end of their service lives while maintaining sleeper-to-sleeper stiffness homogeneity. To confirm that the concrete sleepers can successfully replicate the stiffness properties of the timber sleepers installed in track, field instrumentation was installed under revenue-service train operations on a North American commuter rail transit agency to measure the wheel–rail vertical loads and track displacement. The results indicated that there are minimal differences in median track displacements between timber (2.26 mm, 0.089 in.) and EIC sleepers (2.21 mm, 0.087 in). Using wheel-load data and the corresponding track displacements associated with each wheel load, track modulus values were calculated using the single-point load method based on beam on elastic foundation (BOEF) fundamentals. The calculated values for the track modulus indicated similar performances between the two sleeper types, with median values of 12.95 N/mm/mm (1878 lbs./in./in.) and 12.79 N/mm/mm (1855 lbs./in./in.) for timber sleepers and EIC sleepers, respectively. The field results confirmed the suitability of the new EIC sleeper design in maintaining a consistent track modulus for the location studied, thus evenly sharing loads between and among sleepers manufactured from both concrete and timber.

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.

scholarly journals Influence of train wheel load and arising support imperfections of railway jointless track on its work during operating

2018 ◽  
Vol 2018 (10) ◽  
pp. 1-10
Author(s):  
Włodzimierz Bednarek
Keyword(s):  
Theoretical Calculations ◽  
Threshold Effect ◽  
Considerable Change ◽  
Railway Track ◽  
Negative Effects ◽  
Wheel Load ◽  
Structure Degradation ◽  
Wheel Flat ◽  
Railway Crossing ◽  
Track Bridge

In the paper an analyses of chosen problems of influence of train wheel load and arising imperfections in jointless track on its work during operating are presented. A typical classification of arising imperfections in railway track is shown (on the basis of publications analysis and author's personal researches and analyses). In the paper appearing changes of stiffness between varied constructions (e.g. track–bridge, track–railway crossing) which in literature is defined as threshold effect are presented. An example of analyses of induced and intended imperfection in railway track with field investigations results and author's theoretical calculations are given. It is stated, that special attention shall be paid to wheel flat place significance as the source of following track structure degradation „from the top” and additional force loading railway track. In the paper a negative effects of considerable change of contact and support with rail roadbed are described.

Evaluation of Abrasive Wear of Polymeric Materials Using Single-Pass Pendulum Scratching

2002 ◽  
Author(s):  
Marcelo Torres Piza Paes ◽  
Antonio Marcos Rego Motta ◽  
Lauro Lemos Lontra Filho ◽  
Juliano Ose´ias de Morais ◽  
Sine´sio Domingues Franco
Keyword(s):  
Deep Water ◽  
Wear Mechanisms ◽  
Degradation Mechanism ◽  
Single Point ◽  
Polymeric Materials ◽  
Scratch Resistance ◽  
Wear Behaviour ◽  
Sediment Layer ◽  
Materials Used ◽  
Energy Dissipated

Scratching abrasion due to rubbing against the sediment layer is an important degradation mechanism of flexible cable in deep water oil and natural gas exploitation. The present study was initiated to gain relevant data on the wear behaviour of some commercial materials used to externally protect these cables. So, Comparison tests were carried out using the single-point scratching technique, which consists of a sharp point mounted at the extremity of a pendulum. The energy dissipated during the scratching is used to evaluate the relative scratch resistance. The results showed, that the contact geometry strongly affects the specific scratching energy. Using SEM imaging, it was found, that these changes were related to the operating wear mechanisms. The observed wear mechanisms are also compared with those observed on some cables in deep water operations.

Employing Surface Roughness for Bridge-Vehicle Interaction Based Damage Detection

2011 ◽  
Author(s):  
Vesna Jaksic ◽  
Vikram Pakrashi ◽  
Alan O’Connor
Keyword(s):  
Surface Roughness ◽  
Damage Detection ◽  
Flexural Rigidity ◽  
Single Point ◽  
Point Load ◽  
Ride Quality ◽  
Breathing Crack ◽  
Bernoulli Beam ◽  
Statistical Parameters ◽  
Euler Bernoulli Beam

Damage detection and Structural Health Monitoring (SHM) for bridges employing bridge-vehicle interaction has created considerable interest in recent times. In this regard, a significant amount of work is present on the bridge-vehicle interaction models and on damage models. Surface roughness on bridges is typically used for detailing models and analyses are present relating surface roughness to the dynamic amplification of response of the bridge, the vehicle or to the ride quality. This paper presents the potential of using surface roughness for damage detection of bridge structures through bridge-vehicle interaction. The concept is introduced by considering a single point observation of the interaction of an Euler-Bernoulli beam with a breathing crack traversed by a point load. The breathing crack is treated as a nonlinear system with bilinear stiffness characteristics related to the opening and closing of crack. A uniform degradation of flexural rigidity of an Euler-Bernoulli beam traversed by a point load is also considered in this regard. The surface roughness of the beam is essentially a spatial representation of some spectral definition and is treated as a broadband white noise in this paper. The mean removed residuals of beam response are analyzed to estimate damage extent. Uniform velocity and acceleration conditions of the traversing load are investigated for the appropriateness of use. The detection and calibration of damage is investigated through cumulant based statistical parameters computed on stochastic, normalized responses of the damaged beam due to passages of the load. Possibilities of damage detection and calibration under benchmarked and non-benchmarked cases are discussed. Practicalities behind implementing this concept are also considered.

scholarly journals Analysis of static forces generated in-track on a railway sleeper resting on an elastic foundation due to structural imperfections using the PONTOS system

2019 ◽  
Vol 262 ◽  
pp. 11001
Author(s):  
Włodzimierz Andrzej Bednarek
Keyword(s):  
Theoretical Calculations ◽  
Railway Track ◽  
Bernoulli Beam ◽  
Main Concept ◽  
Field Investigations ◽  
Railway Sleeper ◽  
Foundation Parameters ◽  
Euler Bernoulli Beam ◽  
Structural Imperfections ◽  
Two Parameter

In the paper a considered railway sleeper was analysed as an Euler-Bernoulli beam and a Timoshenko beam of finite length resting on a oneand two-parameter foundation. The foundation parameters were determined based on a modified and analogue Vlasov soil model and field investigations. The main concept for the executed investigations was to induce an intentional imperfection in an actual railway track, propose a way of appropriate measurement (e.g. the PONTOS system by GOM mbh), and utilize author’s field investigations results to calibrate necessary parameters for theoretical calculations. An experimental formula describing the value of the force transferred from the rail to the railway sleeper on the grounds of the survey site caused by a locomotive was given. Furthermore, the deflection of the chosen railway sleeper due to the generated imperfection was analysed. Finally the objective of the present analysis was to resolve the calculations into the beam element such that the results can be utilised in computational railway practice. In the presented paper also the computational examples, diagrams and tables reflecting influence of analyzed parameters on obtained a CWR track’s displacements are enclosed.

scholarly journals A Planar Parallel Device for Neurorehabilitation

Robotics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 104
Author(s):  
Jawad Yamine ◽  
Alessio Prini ◽  
Matteo Lavit Nicora ◽  
Tito Dinon ◽  
Hermes Giberti ◽  
...  
Keyword(s):  
Single Point ◽  
Point Load ◽  
Experimental Procedure ◽  
Rehabilitation Robots ◽  
Parallel Kinematic Mechanism ◽  
Kinematic Behaviour ◽  
3D Printed ◽  
Parallel Kinematic ◽  
Robotic Devices ◽  
Kinematic Optimization

The patient population needing physical rehabilitation in the upper extremity is constantly increasing. Robotic devices have the potential to address this problem, however most of the rehabilitation robots are technically advanced and mainly designed for clinical use. This paper presents the development of an affordable device for upper-limb neurorehabilitation designed for home use. The device is based on a 2-DOF five-bar parallel kinematic mechanism. The prototype has been designed so that it can be bound on one side of a table with a clamp. A kinematic optimization was performed on the length of the links of the manipulator in order to provide the optimum kinematic behaviour within the desired workspace. The mechanical structure was developed, and a 3D-printed prototype was assembled. The prototype embeds two single-point load cells to measure the force exchanged with the patient. Rehabilitation-specific control algorithms are described and tested. Finally, an experimental procedure is performed in order to validate the accuracy of the position measurements. The assessment confirms an acceptable level of performance with respect to the requirements of the application under analysis.

Limit Analysis and Yield-Line Theory

1968 ◽  
Vol 35 (2) ◽  
pp. 357-362 ◽  
Author(s):  
Antoni Sawczuk ◽  
P. G. Hodge
Keyword(s):  
Limit Analysis ◽  
Single Point ◽  
Point Load ◽  
Simply Supported ◽  
Yield Line ◽  
Yield Line Theory ◽  
Line Theory ◽  
The Relationship ◽  
Line Analysis ◽  
General Method

The relationship between limit analysis and yield-line analysis is investigated. Attention is restricted to simply supported, isotropic slabs subjected to single-point loadings. It is found that conventional yield-line analyses quite often give substantial overestimates of the carrying capacity. A general method is formulated for finding the yield-point load, and various examples are considered.

scholarly journals Comparative study on stiffness properties of WOODCAST and conventional casting materials

2012 ◽  
Vol 37 (4) ◽  
pp. 336-339 ◽  
Author(s):  
Eija Pirhonen ◽  
Antti Pärssinen ◽  
Mika Pelto
Keyword(s):  
Mechanical Properties ◽  
Comparative Study ◽  
Clinical Relevance ◽  
Variable Stiffness ◽  
Clinical Use ◽  
Plaster Of Paris ◽  
Synthetic Materials ◽  
Stiffness Properties ◽  
Materials Used ◽  
Cylindrical Samples

Background and Aim: Plaster-of-Paris and synthetic materials (e.g. fibreglass) have been in clinical use as casting materials for decades. An innovative casting material, WOODCAST, brings interesting alternatives to the traditional materials. The aim of this study was to compare the stiffness properties of the WOODCAST material to traditional casting materials. Technique: In immobilization by casting, materials with variable stiffness properties are required. Ring stiffness of cylindrical samples correlates well with cast rigidity. Discussion: For load-bearing structures, the use of the WOODCAST Splint is recommended as equally high stiffness was obtained with the WOODCAST Splint as was with fibreglass. The WOODCAST 2 mm product is optimal for structures where some elasticity is required, and WOODCAST Ribbon can be used in any WOODCAST structure where further reinforcement is needed. The results show that WOODCAST material can be used in replacing traditional casting materials used in extremity immobilization. Clinical relevance The mechanical properties of casting material play an important role in safe and effective fracture immobilization. Stiffness properties of the WOODCAST casting material and conventional materials – fibreglass and plaster-of-Paris – were analysed in this study. The WOODCAST Splint appears to compare favorably with traditional materials such as Scotchcast.

scholarly journals Unified approach for bridge deck design

2021 ◽  
Author(s):  
Karim Meleka
Keyword(s):  
Bridge Deck ◽  
Flexural Rigidity ◽  
Single Point ◽  
Point Load ◽  
Live Load ◽  
Design Code ◽  
Design Alternatives ◽  
Wheel Loading ◽  
Torsionally Stiff ◽  
Concrete Deck

Current Canadian Highway Bridge Design Code includes design provisions to establish live load demands in (i) reinforced concrete decks over longitudinal girders, (ii) orthotropic deck over longitudinal girders, and (iii) orthotropic deck over transverse beams. However, it only provides an equation for factored applied moment on concrete deck under single point load. Similar equations for orthotropic decks are as yet unavailable. As such, parametric study was conducted to lead to new empirical expressions for moment in bridge decks subjected to truck wheel loading considering each of the three cases of orthotropy: (i) relatively torsionally stiff, flexurally soft decks; (ii) relatively uniformly thick decks; and (iii) relatively torsionally soft, flexurally stiff decks. Using the proposed formulations, bridge deck design can be treated in a unified way across different deck types, accounting for longitudinal-transverse flexural rigidity of decks. Application of these methods can significantly simplify the analysis of decks and allow bridge engineers to make comparisons across different deck design alternatives.

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