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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 25 for “"crosstie"”.
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The mechanics of abrasion on concrete crosstie rail seats
… as one of the primary factors limiting concrete crosstie service life, particularly in heavy-haul freight operations. RSD refers to the degradation of the material at the contact interface between the concrete crosstie rail seat and the rail pad assembly that protects the bearing area of the …
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Field test program of the concrete crosstie and fastening system
… program, the design and performance of concrete crossties and elastic fastening systems must be upgraded. As a part of a study aimed at improving concrete crossties and fastening systems, field experimentation was performed at the Transportation Technology Center (TTC) in Pueblo, CO by …
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Quantification of prestressed concrete railway crosstie flexural response: Implications for mechanistic design
Concrete is the dominant crosstie material choice for demanding locations on heavy axle load (HAL) freight railroads with steep grades, sharp curves, and high annual gross tonnage. Concrete crossties are also used in rail transit applications where safety and reliability of infrastructure is at a …
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Prestressed concrete railway crosstie support variability and its effect on flexural demand
… the current structural models used for concrete crosstie flexural analysis and design assume that the ballast bearing support is static and consistently located in a specific region under the crosstie. This assumption implies a linear behavior of the wheel-load bending moment relationship. …
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Mechanistic analysis of concrete crosstie and fastening system using field-validated finite element model
… further investigate the performance of concrete crosstie and fastening system under vertical and lateral wheel load using finite element analysis, and explore possible improvement for current track design standard. The damage of fastening system is one of the most prevalent failure causes for …
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Determination of load path through concrete crosstie and fastening system: a laboratory and field investigation
… load path from rail-wheel to precast concrete crossties. In this research, the behavior of crosstie and fastening system is investigated through material-level, component-level and system-level laboratory and field experiments. The system-level experiments use three primary test setups. One of …
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Understanding the vertical load path under static and dynamic loads in concrete crosstie and fastening systems
… developing a mechanistic design approach for the crossties and fastening systems. It is important to follow the flow of forces through the system to understand the demands on each individual component. In spite of extensive research focusing on the vertical load path a lack of clear understanding …
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Quantification of rail seat load distributions on concrete crossties
… and distribution of load imparted to concrete crosstie rail seats. The rail seat load distribution is critical to the analysis of failure mechanisms associated with rail seat deterioration (RSD), the degradation of the concrete surface at the crosstie rail seat. RSD can lead to wide gauge, cant …
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Flexural behavior of prestressed concrete monoblock crossties
As the use of concrete crossties increases for heavy-haul freight railroad lines in North America, it is becoming more critical to improve the understanding of their flexural behavior. This improved understanding can help to optimize current design and maintenance practices for concrete crossties, …
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Analysis of the performance and failure of railroad concrete crossties with various track support conditions
In North America, the use of concrete crossties has increased steadily over the past decade as they have emerged as an economic alternative to timber crossties to accommodate heavy axle freight train loads. As the number of concrete crossties has grown, the importance of understanding the …
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Freeze-thaw environment of precast concrete crossties and effect of vibration on fresh materials
… lines where timber ties (alternatively known as crossties or sleepers) are being replaced with high performance concrete crossties. Additionally, concrete crossties are being installed in burgeoning high speed rail networks across the United States of America. It has been observed, however, that …
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Multifaceted approach for the analysis of rail pad assembly response
… construction worldwide, advancements in concrete crosstie fastening systems are required. A mechanistic design approach based on scientific principles, derived from extensive laboratory and field investigation and combined with computational analyses, has the potential to improve the current …
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Polypropylene fiber reinforced concrete in railway crossties
Cracking of concrete crossties is a performance problem that reduces service life and increases maintenance costs. While strong in compression, plain concrete is relatively weak and brittle under tensile stresses. Inclusion of synthetic polypropylene macro fibers in concrete is known to improve …
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Air-coupled non-destructive evaluation technology for condition assessment of railroad ties
… parameters indicative of the extent of damage in crossties. A robust “wave front fitting algorithm” is developed to estimate surface wave speed from a B-scan image generated using multiple time domain signals. Five signal parameters, namely surface wave speed from t-x domain, energy of the wave …
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Track model for predicting dynamic responses of railroad bridge approaches
… bridge approaches, also known as the “hanging crosstie” problem, which is caused by several sequential crossties near the bridge abutment experiencing lack-of-support. These crossties with gaps formed underneath undergo oscillatory motion as the dynamic loading from moving wheels push and pull …
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Finite element analysis of railway track under vehicle dynamic impact and longitudinal loads
… element (FE) method. An FE model with multiple crossties and their accompanying fastening systems is developed and utilized in this study after being validated using field data. The results of the impact load study indicate that impact loading consists of direct wheel impact loads and track …
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Development of ice-bonded ballast in sub-freezing temperatures and its effect on maintenance operations during a winter rail break
… restrain the track system has been quantified by crosstie-type and ballast condition (e.g., consolidated or disturbed). Sub-freezing temperatures produce the largest differentials between the rail temperature and RNT (rail neutral temperature) [i.e., differential temperatures (dTs) exceeding 30⁰C …
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Flexural distress and degradation mechanisms in pretensioned concrete beams and railroad crossties
Crossties (sleepers) are an essential component of ballasted railroad track and concrete is a commonly used material for crossties in demanding locations such as heavy axle load (HAL) freight railroads, high-speed rail lines, and rail transit systems. Concrete crossties are often designed as …
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Analysis of the design of railroad track superstructure components for rail transit applications
… performance of prestressed monoblock concrete crossties and premium elastic fastening systems, this project aimed to quantify the behavior of the aforementioned track superstructure elements under different rail transit loading conditions. Instrumentation was deployed at three different North …
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Increasing residual structural capacity of cracked concrete railroad crossties with polypropylene fibers
… polypropylene fibers into concrete railroad crossties to increase its residual structural capacity once the concrete has cracked. The center negative flexural cracking is considered as a serious failure mode in concrete railroad crossties, which decreases structural capacity and results in …
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