scholarly journals A discussion for the reduction in the length of a prestressed concrete railway tie in time

2021 ◽  
Author(s):  
Niyazi Özgür Bezgin
Keyword(s):  
Prestressed Concrete ◽  
High Strength ◽  
Railway Track ◽  
Structural Elements ◽  
Track Maintenance ◽  
Concrete Shrinkage ◽  
Prestressing Force ◽  
Steel Wires ◽  
Practical Evaluation ◽  
And Performance

Increasing train speeds, contemporary requirements for reduced track maintenance costs and extended track service lives required the development and use of reinforced concrete and prestressed concrete ties. Railway engineers began to use concrete for their bi-block and monoblock railway ties heavily, following the development of an understanding for design and performance of concrete structures, production of high strength steel wires and preferable economy of prefabricated mass production for reinforced and prestressed concrete structural elements following the first half of 20th Century. Structural elements of a railway track such as reinforced or prestressed concrete ties have strict production tolerances that are not common for ordinary structural elements. Production of concrete railway ties takes place under strict dimensional control that ensures a nominal design gauge width for the railway track. Design specifications for prestressed monoblock ties frequently specify the gauge width and the shoulder width to be within 1 mm of the design width. However, prestressed concrete ties experience shortenings in length due to transfer of the prestressing force known as instant elastic shortening and shortenings due to concrete shrinkage and concrete creep in time that also relate to ambient relavite humidity. The author conducted numerous studies on the matter, showed by calculation, and observed experimentally that if unaccounted for, such shortenings can surpass the allowed tolerances in time and result in the rejection of the produced tie for use in the railway track. This paper refers to previous studies by the author that brought international attention on the issue and presents a thorough and a practical evaluation of time related changes in tie lengths for a particular design for prestressed concrete monoblock ties under varying ambient humidity conditions.

scholarly journals Optimization of ER8 and 42CrMo4 Steel Rail Wheel for Road–Rail Vehicles

2020 ◽  
Vol 10 (14) ◽  
pp. 4717
Author(s):  
Filip Lisowski ◽  
Edward Lisowski
Keyword(s):  
Geometry Optimization ◽  
High Strength ◽  
Railway Track ◽  
Hydraulic Motor ◽  
Steel Rail ◽  
Element Analysis ◽  
Track Maintenance ◽  
Rail Vehicles ◽  
First Order Method ◽  
Failure Site

Railway track maintenance services aim to shorten the time of removing failures on the railways. One of the most important element that shorten the repair time is the quick access to the failure site with an appropriate equipment. The use of road-rail vehicles is becoming increasingly important in this field. In this type of constructions, it is possible to use proven road vehicles such as self-propelled machines or trucks running on wheels with tires. Equipping these vehicles with a parallel rail drive system allows for quick access to the failure site using both roads and railways. Steel rail wheels of road-rail vehicles are designed for specific applications. Since the total weight of vehicle is a crucial parameter for roadworthiness, the effort is made to minimize the mass of rail wheels. The wheel under consideration is mounted directly on the hydraulic motor. This method of assembly is structurally convenient, as no shafts or intermediate couplings are required. On the other hand, it results in strict requirements for the wheel geometry and can cause significant stress concentration. Therefore, the problem of wheel geometry optimization is discussed. Consideration is given to the use of ER8 steel for railway application and 42CrMo4 high-strength steel. Finite element analysis within Ansys software and various optimization tools and methods, such as random tool, subproblem approximation method and first-order method are applied. The obtained results allow to minimize the rail wheel mass with respect to the used material. Moreover, computational demands and methods leading to the best results are compared.

Experimental Study and Performance Analysis of Concrete Shrinkage-Reducing Agents

2011 ◽  
Vol 311-313 ◽  
pp. 1879-1883
Author(s):  
Yong Cun Zhang ◽  
Qing Ning Li
Keyword(s):  
Drying Shrinkage ◽  
High Strength ◽  
Butyl Alcohol ◽  
Reducing Agents ◽  
Chemical Components ◽  
Concrete Shrinkage ◽  
Mortar Strength ◽  
Tert Butyl Alcohol ◽  
Concrete Blocks ◽  
And Performance

This paper will focus on developing a sort of concrete shrinkage-reducing agents that are generally some surfactants on the basis of some tests. By reference to the main chemical components of some domestic and foreign agents, the following chemicals are initially selecting : tert-butyl alcohol, triethanolamine and polyvinyl alcohol, and then some experiments about these substances were made, including liquid surface tension test, high-strength cement mortar shrinkage test, mortar strength test. Finally, the medicals that can significantly reduce drying shrinkage deformation but have little effect on the strenth of concrete blocks,are selected out as available concrete shrinkage-reducing agents.

Weldable Aluminum Alloys in Aerospace and Transportation

2019 ◽  
Author(s):  
Alexey Sverdlin
Keyword(s):  
Composite Materials ◽  
Aluminum Alloys ◽  
Aerospace Industry ◽  
High Strength ◽  
Performance Characteristics ◽  
Structural Elements ◽  
Extensive Experience ◽  
And Performance ◽  
The Individual ◽  
High Strength Aluminum Alloys

Fabrication of high-strength aluminum alloys with the application of welding is one of the most important directions for increasing efficiency and performance characteristics of the aircraft. Today, the aerospace industry has accumulated extensive experience in the application of welded aluminum alloys. Of course, the individual structural elements are made of steel, titanium alloys, or composite materials, which increase the reliability and functionality of the designs in general.

Combining Track Quality and Performance Measures to Assess Track Maintenance Requirements

2015 ◽  
Author(s):  
Alireza Roghani ◽  
Renato Macciotta ◽  
Michael Hendry
Keyword(s):  
Railway Track ◽  
Threshold Values ◽  
Track Geometry ◽  
Track Maintenance ◽  
Different Types ◽  
Track Stiffness ◽  
And Performance ◽  
Maintenance Requirements ◽  
The Relationship ◽  
Track Quality

The serviceability of a section of railway highly depends on track stiffness and roughness. Railway operators regularly measure parameters associated with track stiffness and roughness to evaluate the track conditions. These measures are used in combination with performance observations to assess maintenance requirements. Although these assessments are mostly qualitative, railway operations have benefited from them. Railway operators keep comprehensive records of different types of track defects along their lines. These records are a measure of track performance and present an opportunity to quantify the relationship between track quality and performance. This brings the possibility of developing a performance-based approach for assessing the maintenance requirement along a railway track. In this paper, a database of track geometry defects along Canadian National Railway’s Lac la Biche subdivision (Alberta) has been compared against measured parameters associated with track roughness and stiffness. The analyses confirm the relationship between track stiffness and roughness, and the occurrence of track defects. This relationship is further used to define threshold values of track roughness and stiffness, and a hazard chart for maintenance requirements along the Lac la Biche subdivision is proposed.

Application of Prestressed CFRP Textiles for the Development of Thin- Walled Concrete Structural Elements

2019 ◽  
Author(s):  
Juan Pablo Osman Letelier ◽  
Alex Hückler ◽  
Mike Schlaich
Keyword(s):  
Prestressed Concrete ◽  
High Strength ◽  
Experimental Tests ◽  
Sustainable Construction ◽  
Structural Elements ◽  
Prestressing Steel ◽  
Thin Walled Structures ◽  
Reinforced Polymer ◽  
Thin Walled ◽  
Doubly Curved

<p>The success story of prestressed concrete is based on the utilization of high‐strength prestressing steel which enables large compressive forces to be introduced into the concrete. However, thin‐walled concrete structures often require considerable thicknesses for the sole purpose of preventing corrosion of the steel elements. In this paper the use of prestressed Carbon Fiber Reinforced Polymer (CFRP) for the development of thin‐walled concrete structural elements is briefly presented. The transition of material to stronger, lighter and corrosion‐resistant CFRP represents a significant improvement in concrete construction. Prestressing with CFRP elements leads to more slender and thereby more economical and durable structural elements. Through the additional prestressing of a reinforcement mesh, very light and highly rigid surface structures can be constructed. Prestressing technologies have been developed and adapted for specific applications i.e. slabs and doubly curved structural elements and validated by experimental tests. This paper shows that prestressed carbon reinforced concrete can be used for more durable and efficient thin‐walled structures, allowing for more sustainable construction.</p>

High-Strength Reduced-Modulus High Performance Concrete (HSRM-HPC) for Prestressed Concrete Tie Applications

2016 ◽  
Author(s):  
Dimitrios C. Rizos
Keyword(s):  
Performance Assessment ◽  
Prestressed Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Experimental Testing ◽  
High Strength ◽  
Highway Bridges ◽  
Material Development ◽  
Reduced Modulus ◽  
And Performance

A High-Strength Reduced-Modulus High Performance Concrete (HSRM-HPC) for use in prestressed concrete rail ties has been developed by the authors. The HSRM-HPC material was originally considered for highway bridges but was rejected because of the accidental finding of the low modulus of elasticity. It is shown that the elastic modulus of the HSRM-HPC is reduced as much as 50% compared to the conventional HPC of the same strength while preserving all other properties of the conventional HPC. The use of the more flexible HSRM-HPC in concrete ties leads to reduced stress amplitudes and regularized stress fields at the rail seat area and the middle segment of the tie, which are the two most critical areas of tie failure. This work discusses the development and characterization of the HSRM HPC material, as well as current work on the performance assessment of such ties. The material development, material characterization, and performance assessment is conducted through experimental testing and computer simulations. The benefits of HSRM-HPC ties are quantified and discussed.

scholarly journals A Taxonomy of Railway Track Maintenance Planning and Scheduling: A Review and Research Trends

2021 ◽  
pp. 107827
Author(s):  
Mahdieh Sedghi ◽  
Osmo Kauppila ◽  
Bjarne Bergquist ◽  
Erik Vanhatalo ◽  
Murat Kulahci
Keyword(s):  
Research Trends ◽  
Railway Track ◽  
Maintenance Planning ◽  
Planning And Scheduling ◽  
Track Maintenance

scholarly journals Smart Sensing of PSC Girders Using a PC Strand with a Built-in Optical Fiber Sensor

2021 ◽  
Vol 11 (1) ◽  
pp. 359
Author(s):  
Sung Tae Kim ◽  
Hyejin Yoon ◽  
Young-Hwan Park ◽  
Seung-Seop Jin ◽  
Soobong Shin ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Prestressed Concrete ◽  
Steel Wire ◽  
Optical Fiber Sensor ◽  
Fiber Reinforced Polymer ◽  
Bridge Structure ◽  
Fbg Sensor ◽  
Prestressing Force ◽  
Reinforced Polymer ◽  
Loading Tests

This paper presents a multi-functional strand capable of introducing prestressing force in prestressed concrete (PSC) girders and sensing their static and dynamic behavior as well. This innovative strand is developed by replacing the core steel wire of the strand used in PSC structures with a carbon fiber-reinforced polymer (CFRP) wire with a built-in optical Fiber Bragg Grating (FBG) sensor. A full-scale girder specimen was fabricated by applying this multi-function strand to check the possibility of tracking the change of prestressing force at each construction stage. Moreover, dynamic data could be secured during dynamic loading tests without installing accelerometers and made it possible to obtain the natural frequencies of the structure. The results verified the capability to effectively manage the prestressing force in the PSC bridge structure by applying the PC strand with a built-in optical sensor known for its outstanding practicability and durability.

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