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Full-Text Articles in Engineering Science and Materials

Rail Squats: Understand Its Causes, Severity, And Non-Destructive Evaluation Techniques, Sakdirat Kaewunruen, Makoto Ishida Jul 2015

Rail Squats: Understand Its Causes, Severity, And Non-Destructive Evaluation Techniques, Sakdirat Kaewunruen, Makoto Ishida

Sakdirat Kaewunruen

Generally, rail squats are defined by the growth of any cracks that have grown longitudinally through the rail subsurface and some of the cracks propagating to the bottom of rails transversely have branched from initial longitudinal cracks with a depression of rail surface. The rail defects are commonly referred to as ‘squats’ when they were initiated from damage caused by rolling contact fatigue, and as ‘studs’ when they were associated with white etching layer caused by the transform from pearlitic steel due to friction heat generated by wheel sliding or excessive traction. Such rail surface defect induces wheel/rail impact and …


Achieving Carbon Efficiency In Construction And Maintenance Of Railway Turnouts, Crossovers And Diamonds, Sakdirat Kaewunruen, Steve Krezo, Olivia Mirza, Yapping He, Joseph M. Sussman Jul 2015

Achieving Carbon Efficiency In Construction And Maintenance Of Railway Turnouts, Crossovers And Diamonds, Sakdirat Kaewunruen, Steve Krezo, Olivia Mirza, Yapping He, Joseph M. Sussman

Sakdirat Kaewunruen

Railway turnouts, crossovers, and diamonds are special track systems used to divert a train from a particular direction or a particular track onto other directions or other tracks. It is a structural grillage system that consists of steel rails, points, crossings, steel plates, rubber pads, insulators, fasteners, screw spikes, beam bearers (either timber, polymer, steel or concrete), ballast and formation. Usually under dynamic and high-intensity impact loading conditions, structural components of the turnout tend to have relatively short lives compared with those of ordinary open railway tracks, resulting in frequent turnout re- construction and maintenance (ranging from every 10 to …


Severity And Growth Evaluation Of Rail Corrugations On Sharp Curves Using Wheel/Rail Interaction, Sakdirat Kaewunruen, Steve Marich Jul 2015

Severity And Growth Evaluation Of Rail Corrugations On Sharp Curves Using Wheel/Rail Interaction, Sakdirat Kaewunruen, Steve Marich

Sakdirat Kaewunruen

A railway network generally spans over a large distance so the structural health monitoring of such a rail infrastructure system is one of the critical challenges in rail industry practice. Especially in an underground/subway or elevated system, the facilities, resources and time period permitted for critical infrastructure inspection and maintenance is considerably limited. As a result, the automated inspection system of railway is in very high demand. Rail corrugation defect is the periodic, undulated or wave-like vertical alignment of rail surface. The wavelength and severity of rail corrugations is dependant to track structure, track geometry, traction system, rail vehicle behaviours, …


Under Sleeper Pads: Field Investigation Of Their Role In Detrimental Impact Mitigation, Sakdirat Kaewunruen, Alex M. Remennikov Jun 2015

Under Sleeper Pads: Field Investigation Of Their Role In Detrimental Impact Mitigation, Sakdirat Kaewunruen, Alex M. Remennikov

Sakdirat Kaewunruen

Under sleeper pads (USPs) are the component installed under the concrete sleepers generally to improve railway track resilience. Initial development in Europe, particularly in Austria, has encouraged the adoption of the component around the world. In practice, the component has commonly been used in certain applications, mainly to moderate track stiffness in special locations such as turnouts, crossings, and level crossing. In heavy haul operation, the heavier wagons result in sturdier bogie structures, higher unsprung mass, and then higher level of wheel-rail interaction forces. Accordingly, the application of USPs to mitigate detrimental impact load consequence on track structure is presented …


Design Of Holes And Web Openings In Railway Prestressed Concrete Sleepers, Erosha Kahawatta Gamage, Sakdirat Kaewunruen, Alex M. Remennikov Jun 2015

Design Of Holes And Web Openings In Railway Prestressed Concrete Sleepers, Erosha Kahawatta Gamage, Sakdirat Kaewunruen, Alex M. Remennikov

Sakdirat Kaewunruen

As the crosstie beam in railway track systems, the prestressed concrete sleepers (or railroad ties) are principally designed in order to carry wheel loads from the rails to the ground. Their design takes into account static and dynamic loading conditions. It is evident that prestressed concrete has played a significant role as to maintain the high endurance of the sleepers under low to moderate repeated impact loads. In spite of the most common use of the prestressed concrete sleepers in railway tracks, there have always been many demands from rail engineers to improve serviceability and functionality of concrete sleepers. For …


Impact Responses Of Prestressing Tendons In Railway Concrete Sleepers In High Speed Rail Environments, Sakdirat Kaewunruen, Alex M. Remennikov May 2015

Impact Responses Of Prestressing Tendons In Railway Concrete Sleepers In High Speed Rail Environments, Sakdirat Kaewunruen, Alex M. Remennikov

Sakdirat Kaewunruen

Prestressed concrete sleepers (or railroad ties) are designed in order to carry and transfer the wheel loads from the rails to the ground and are installed as the crosstie beam support in railway track systems. They are subjected to impact loading conditions that are resulted from train operations over wheel or rail abnormalities, such as flat wheels, dipped rails, crossing transfers, rail squats, corrugation, etc. The magnitude of the shock load relies on various factors such as axle load, types of wheel/rail imperfections, speeds of vehicle, track stiffness, etc. This paper demonstrates the development of finite element modelling to evaluate …


Finite Element Modelling Of Modular Precast Composites For Railway Track Support Structure – A Battle To Save Sydney Harbour Bridge, Dane Griffin, Olivia Mirza, Kenny Kwok, Sakdirat Kaewunruen Apr 2015

Finite Element Modelling Of Modular Precast Composites For Railway Track Support Structure – A Battle To Save Sydney Harbour Bridge, Dane Griffin, Olivia Mirza, Kenny Kwok, Sakdirat Kaewunruen

Sakdirat Kaewunruen

Railway networks in Australian alone require replacing a large amount of aging timber components in excess of 280,000 m3 per year. The replacement of timber track components is responsible for producing greenhouse gas emissions 6 times greater than equivalent reinforced concrete counterparts. Sydney Harbour Bridge presently experiences similar problem. A feasibility study to develop an innovative solution for the replacement of aging timber transoms installed on the Sydney Harbour Bridge was conducted to evaluate environmental, safety and financial benefits. The development of alternative composite structure to replace the timber components overcomes some potential compatibility issues with track stiffness as well …


Field Monitoring Of Rail Squats Using 3d Ultrasonic Mapping Technique, Sakdirat Kaewunruen, Makoto Ishida Nov 2014

Field Monitoring Of Rail Squats Using 3d Ultrasonic Mapping Technique, Sakdirat Kaewunruen, Makoto Ishida

Sakdirat Kaewunruen

Rail squats and studs are typically classified as the propagation of any cracks that have grown longitudinally through the subsurface. Some of the cracks could propagate to the bottom of rails transversely, which have branched from the initial longitudinal cracks with a depression of rail surface. The rail defects are commonly referred to as ‘squats’ when they were initiated from damage layer caused by rolling contact fatigue, and as ‘studs’ when they were associated with white etching layer caused by the transform from pearlitic steel due to friction heat generated by wheel sliding or excessive traction. Such above-mentioned rail defects …


Think Outside The Box: New Materials, Design Application, And Performance Of Railway Turnout Bearers, Sakdirat Kaewunruen May 2014

Think Outside The Box: New Materials, Design Application, And Performance Of Railway Turnout Bearers, Sakdirat Kaewunruen

Sakdirat Kaewunruen

Railway turnout systems are a main feature in railway tracks. There are two types of turnout support structures, which can be designed to be either a slab or a cluster of discrete bearers. The choice of turnout support system depends on asset management strategy of the rail operators or maintainers. This paper will focus on the discrete turnout bearer system where turnout alignments, settlement and deformation are comparatively more flexible and retrievable by routine ballast tamping. It embraces the consideration of new materials for use as a turnout bearer. Traditional bearer materials are timber, steel, and concrete. Recent developments have …


Dynamic Responses Of Railway Bridge Ends: A Systems Performance Improvement By Application Of Ballast Glue/Bond, Sakdirat Kaewunruen Apr 2014

Dynamic Responses Of Railway Bridge Ends: A Systems Performance Improvement By Application Of Ballast Glue/Bond, Sakdirat Kaewunruen

Sakdirat Kaewunruen

Accelerated deterioration of railway bridge approaches often induces downtime or restricted railway operation; and importantly causes more frequent maintenance, which is costly and time-consuming. Such deterioration is believed to occur because of high dynamic impact loading from: the difference of stiffness between the railway track and the bridge; and the poor condition of the track support at the bridge ends. The abrupt change in track stiffness often causes accelerated degradation of the track geometry and components and poor ride quality, demanding higher maintenance. There are a number of improvement programs that have been implemented in order to provide a smooth …


Monitoring In-Service Performance Of Fibre-Reinforced Foamed Urethane Sleepers/Bearers In Railway Urban Turnout Systems, Sakdirat Kaewunruen Mar 2014

Monitoring In-Service Performance Of Fibre-Reinforced Foamed Urethane Sleepers/Bearers In Railway Urban Turnout Systems, Sakdirat Kaewunruen

Sakdirat Kaewunruen

Special track systems used to divert a train to other directions or other tracks are generally called \'railway turnout\'. A traditional turnout system consists of steel rails, switches, crossings, steel plates, fasteners, screw spikes, timber bearers, ballast and formation. The wheel rail contact over the crossing transfer zone has a dip-like shape and can often cause detrimental impact loads on the railway track and its components. The large impact also emits disturbing noises (either impact or ground-borne noise) to railway neighbors. In a brown-field railway track where an existing aged infrastructure requires renewal or maintenance, some physical constraints and construction …


Influence Of Ballast Conditions On Flexural Responses Of Railway Concrete Sleepers, Sakdirat Kaewunruen, Alex M. Remennikov Jan 2009

Influence Of Ballast Conditions On Flexural Responses Of Railway Concrete Sleepers, Sakdirat Kaewunruen, Alex M. Remennikov

Sakdirat Kaewunruen

Railway sleepers in track systems are usually modeled using the beam on elastic foundation theory. In reality, the sleeper-supported ballast is of highly frictional granular media but does not provide any tensile resistance. This paper presents a finite element model of a railway sleeper in a track system, taking into account the tensionless nature of the elastic support. The highlight of this paper is the effect of ballast distributions on the flexural responses of railway sleepers in track systems. Using a finite element package STRAND7, the finite element model updating of the concrete sleeper was earlier developed and validated against …