scholarly journals Field Tests on Eco-Friendly Railway Precast Concrete Slab

2020 ◽  
Vol 10 (12) ◽  
pp. 4140 ◽  
Author(s):  
Taehoon Koh ◽  
Moochul Shin
Keyword(s):  
Reinforced Concrete ◽  
South Korea ◽  
Concrete Slab ◽  
Precast Concrete ◽  
Field Tests ◽  
Field Performance ◽  
Railway Track ◽  
Track Structure ◽  
Structure System ◽  
Slab Track

This study focuses on evaluating the field performance of a newly developed eco-friendly precast concrete slab track structure for railway/subway systems in Seoul, South Korea. Although Ballasted railway track structures are one of the most common track structures in the railway industry, they have some drawbacks including higher maintenance cost, un-uniform supports, and a high level of noise and vibration. However, a ballastless (slab-based) track structure system requires less maintenance and uniform support conditions, as well as several ballastless structure systems developed for high-speed trains. The Seoul Metro subway in South Korea has developed a ballastless reinforced concrete (RC) slab railway system using a type of conventional concrete. This study presents a ballastless precast concrete slab using a newly developed eco-friendly concrete, which can significantly improve structural performances and the manufacturability of a railway track structure system. This study evaluates the field performance of the eco-friendly concrete slab system deployed in one of the existing tunnel sections of the Seoul Metro subway system. A total of 10 m long slab sections including a 5 m long eco-friendly “ballasted track to slab track (B2S)” panels section and a 5 m long conventional B2S panels section are installed and monitored side by side. Field tests are performed to measure the level of noise, vibration, dynamic wheel load, rail displacement, and rail stress. The field measurements from the eco-friendly B2S section are compared to those of the conventional reinforced concrete slab track systems. The results show that the performance of the new B2S system using the eco-friendly concrete is comparable and/or superior to the conventional system.

scholarly journals Deformation Law and Control Limit of CRTSIII Slab Track under Subgrade Frost Heave

2021 ◽  
Vol 11 (8) ◽  
pp. 3520
Author(s):  
Xiaopei Cai ◽  
Qian Zhang ◽  
Yanrong Zhang ◽  
Qihao Wang ◽  
Bicheng Luo ◽  
...  
Keyword(s):  
High Speed ◽  
Base Plate ◽  
Element Model ◽  
Middle Part ◽  
Railway Track ◽  
Frost Heave ◽  
Track Structure ◽  
Slab Track ◽  
Plastic Damage ◽  
Track Irregularity

In order to find out the influence of subgrade frost heave on the deformation of track structure and track irregularity of high-speed railways, a nonlinear damage finite element model for China Railway Track System III (CRTSIII) slab track subgrade was established based on the constitutive theory of concrete plastic damage. The analysis of track structure deformation under different subgrade frost heave conditions was focused on, and amplitude the limit of subgrade frost heave was put forward according to the characteristics of interlayer seams. This work is expected to provide guidance for design and construction. Subgrade frost heave was found to cause cosine-type irregularities of rails and the interlayer seams in the track structure, and the displacement in lower foundation mapping to rail surfaces increased. When frost heave occured in the middle part of the track slab, it caused the greatest amount of track irregularity, resulting in a longer and higher seam. Along with the increase in frost heave amplitude, the length of the seam increased linearly whilst its height increased nonlinearly. When the frost heave amplitude reached 35 mm, cracks appeared along the transverse direction of the upper concrete surface on the base plate due to plastic damage; consequently, the base plate started to bend, which reduced interlayer seams. Based on the critical value of track structures’ interlayer seams under different frost heave conditions, four control limits of subgrade frost heave at different levels of frost heave amplitude/wavelength were obtained.

scholarly journals Experimental Study of the Influence of Extremely Repeated Thermal Loading on a Ballastless Slab Track-Bridge Structure

2020 ◽  
Vol 10 (2) ◽  
pp. 461 ◽  
Author(s):  
Lingyu Zhou ◽  
Tianyu Wei ◽  
Guangchao Zhang ◽  
Yingying Zhang ◽  
Mahunon Akim Djibril Gildas ◽  
...  
Keyword(s):  
Thermal Loading ◽  
Reduction Rate ◽  
Railway Track ◽  
Track Structure ◽  
Structural System ◽  
Loading Test ◽  
Slab Track ◽  
Loading Tests ◽  
Three Stages ◽  
Track Bridge

To study the initiation and expansion of the interlayer gap of the China Railway Track System Type II (CRTS-II) ballastless slab track structure under the action of repeated thermal loading as well as the influence of the interlayer gap on the displacement, strain and stiffness of the track structure, a 1/4 scale three-span ballastless slab track simply supported bridge structural system specimen was developed and 18 cycles of extremely thermal loading tests were carried out. Static loading tests were carried out before and after the repeated thermal loading test and the effects of the repeated temperature loading on the mechanical properties of the structural system were analyzed. The test results show that under repeated temperature loading, there is a gap between the track slab and cement emulsified asphalt (CA) mortar near the fixed end section of the beam (close to the shear slots). The interlayer gap gradually expands to the mid-span section in a “stepped” shape in three stages: initiation, expansion and stabilization. Under the same temperature load, the camber of the concrete box beam decreases gradually while that of the track structure increases gradually with the increase of the interlayer gap length. During the three stages of interlayer gap development, the track structure stiffness degrades gradually, and the fastest reduction rate during the expansion stage. At the end of the 18th cycle of thermal loading, a degradation of 14.96% and 2.52% is observed in the stiffness of the track structure and that of the ballastless track-bridge structural system, respectively.

Floating Slab Railway Track for Isolation of Vibration: Models of Infinite Length

1997 ◽  
Author(s):  
James A. Forrest
Keyword(s):  
Vibration Isolation ◽  
Concrete Slab ◽  
Dynamic Stiffness ◽  
Railway Track ◽  
Total Force ◽  
Infinite Length ◽  
Length Unit ◽  
Slab Track ◽  
Transmitted Force ◽  
Rubber Bearings

Abstract Vibration transmitted from underground railways into nearby buildings is an increasingly significant problem affecting high-value residential and commercial developments. Various forms of vibration isolation are used in underground railways, one of which is the ‘floating slab track’. Rails are fixed directly to a massive concrete slab which in turn rests on a resilient mounting (usually rubber bearings or steel springs) so isolating the track from the tunnel invert. The effectiveness of vibration attenuation does not compare well with the simple mass-spring models typically used in the design of floating slab track. This paper develops a model for floating slab track by conceptualising the track as two infinite beams (representing the rail and the concrete slab) separated by elastic layers representing the resilient elements used in floating slab track construction. A dynamic model for a finite-length unit of track is obtained from this physical model by the dynamic-stiffness-matrix method. A repeating unit method is utilised to create track models of infinite length from the finite track unit, an approach which much reduces the computation required. A concept of total force transmitted to the ground for a given set of inputs on the rail is developed, and the effect of various track parameters on the transmitted force is examined.

scholarly journals Study on the Applicability of Short Fiber Reinforced Concrete to Precast Concrete Slabs for Slab Track

2008 ◽  
Vol 49 (1) ◽  
pp. 40-46 ◽  
Author(s):  
Takatada TAKAHASHI ◽  
Etuo SEKINE ◽  
Takahiro HORIIKE ◽  
Shigeru MATSUOKA ◽  
Hideki HOSHIRO
Keyword(s):  
Reinforced Concrete ◽  
Precast Concrete ◽  
Short Fiber ◽  
Fiber Reinforced Concrete ◽  
Concrete Slabs ◽  
Fiber Reinforced ◽  
Slab Track

Experimental and numerical assessment of the flexural behaviour of semi-precast-reinforced concrete slabs

2020 ◽  
Vol 23 (9) ◽  
pp. 1865-1879
Author(s):  
MI Sifan Mohamed ◽  
Julian Ajith Thamboo ◽  
Thuraisingam Jeyakaran
Keyword(s):  
Reinforced Concrete ◽  
Bond Strength ◽  
Surface Treatment ◽  
Concrete Slab ◽  
Precast Concrete ◽  
Small Scale ◽  
Flexural Behaviour ◽  
Interface Shear ◽  
Reinforced Concrete Slab ◽  
Reinforced Concrete Slabs

Semi-precast-reinforced concrete slab system offers more economic method of construction as it minimises the need of formwork at site. The assembly of semi-precast slab system involves two steps: (1) casting of semi-precast slab at the yard and (2) overtopping of concrete at the site. One of the main factors that influence the performance of such slab system is the interface bonding between precast and overtopping concrete. Therefore, in order to better understand the performance of this slab system, a research was carried out to investigate the influence of surface treatment methodologies to the overall flexural behaviour through experimental and numerical studies. In total, five representative semi-precast slabs were constructed and tested to assess the flexural performance with different surface preparation methods and concrete overtopping. Further small-scale precast with overtopped concrete couplets and triplets were casted and tested as the representative semi-precast concrete slab types to examine the interface shear and tensile bond strength characteristics with those different surface treatments. The experimental results revealed that the surface treatment methods have influenced the flexural behaviour of the slabs, where the interface shear bond strength exceeds more than 1.0 MPa and the slab system behaves monolithically under flexural action. Moreover, numerical modelling technique for this slab system was developed based on the finite element framework to further analyse the overall flexural behaviour. Subsequently, good agreements between experimental and developed numerical model results were found. Finally, parametric analyses were performed to further assess the influences of concrete strengths, spans and reinforcement ratios on the safe imposed pressure applicable for this slab system.

scholarly journals Comparison of Carbon Dioxide Emissions of the Ordinary Reinforced Concrete Slab and the Voided Slab System During the Construction Phase: A Case Study of a Residential Building in South Korea

2019 ◽  
Vol 11 (13) ◽  
pp. 3571 ◽  
Author(s):  
Inkwan Paik ◽  
Seunguk Na
Keyword(s):  
Carbon Dioxide ◽  
Life Cycle ◽  
Reinforced Concrete ◽  
South Korea ◽  
Construction Industry ◽  
Carbon Dioxide Emissions ◽  
Building Materials ◽  
Concrete Slab ◽  
Reinforced Concrete Slab

The construction industry not only consumes a lot of energy but also emits large volumes of carbon dioxide. Most countries have established target reduction values of the carbon dioxide emissions to alleviate environmental burdens and promote sustainable development. The reduction in carbon dioxide emissions in the construction industry has been taking place in various ways as buildings produce large quantities of the carbon dioxide over their construction life cycle. The aim of this study is to assess and compare the carbon dioxide emissions of an ordinary reinforced concrete slab and the voided slab system applied to a case study involving a commercial-residential complex building in South Korea. Process-based life-cycle assessment (LCA) is adopted to compute the carbon dioxide emissions during the construction phase, which includes all processes from material production to the end of construction. The results indicate that the total CO2 emissions are 257,230 and 218,800 kg CO2 for the ordinary reinforced concrete slab and the voided slab system, respectively. The highest contributor to CO2 reduction is the embodied carbon dioxide emissions of the building materials, which accounts for 34,966 kg CO2. The second highest contributor is the transportation of the building materials, accounting for 3417 kg CO2.

scholarly journals Analysis of Dynamic Characteristics of Deformed Concrete Slab Track on Transition Zone in High-Speed Train Line According to Train Speeds

2020 ◽  
Vol 10 (20) ◽  
pp. 7174
Author(s):  
Sungbum Park ◽  
Ja Yeon Kim ◽  
Jongwon Kim ◽  
Sehee Lee ◽  
Kook-Hwan Cho
Keyword(s):  
Numerical Analysis ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Concrete Slab ◽  
Field Tests ◽  
Analysis Model ◽  
Transition Zones ◽  
Slab Track ◽  
Speed Range ◽  
Train Speed

A concrete track, such as Rheda 2000 is commonly used in high-speed railways in Korea, Germany, China, etc., to enhance the operational safety of trains and to reduce the maintenance costs. However, when settlement of embankment or a crack in the concrete slab track occurs, the durability of the concrete track deteriorates significantly. Transition zones are considered to be vulnerable and are often deformed in railway embankments. The characteristics of track support stiffness and stresses on the rail in a deformed section are different from those in an undeformed section. In this study, a field measurement and numerical analysis were carried out to identify the dynamic response on transition zones where the track is deformed. A numerical analysis model was built to simulate the deformed concrete slab track, and it was compared with measured data from field tests for verification. The field tests to measure the stresses on the rail were performed in a train speed range from 280 to 300 km/h. According to the numerical analysis, the dynamic characteristics of the track varied with train speeds, which were then compared with the allowable stresses of the concrete slab track.

Reconstruction of the Reinforced-Concrete Railway Bridge in km 3,668 – Argentinská of the Track Bubeneč – Holešovice in Prague

2015 ◽  
Vol 1106 ◽  
pp. 191-194
Author(s):  
Jan Sýkora ◽  
Michal Hacaperka ◽  
Jiří Lukeš ◽  
Stanislav Rosenthal
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Railway Track ◽  
Railway Bridge ◽  
Technical Documentation ◽  
Reinforced Concrete Slab ◽  
Expansion Joints ◽  
In Situ Conditions ◽  
Pile Caps ◽  
Bridge Reconstruction

This article provides a brief review of a reconstruction of the railway bridge in kilometer 3,668 of the railway-track Prague Bubeneč – Prague Holešovice. Specifically, the object is a 10-span reinforced-concrete slab bridge of spans app. 10x 20m carrying two railway-tracks. The reconstruction comprised of a superstructure waterproofing replacement, reconstruction or replacement of cornices and bridge seat at abutment O2 and replacement of all bearings and expansion joints.The bridge’s operation had to be maintained during reconstruction so replacement of bearings and expansion joints was carried out on an uplifted superstructure. Reconstruction of upper part (cornices, waterproofing and expansion joints) was conducted transversally by halves of bridge so operation was maintained at least on one of the railway-tracks.During the process, after consulted with SŽDC, some technical aspects of the original technical documentation from 2008 were changed according to an actual in-situ conditions and contractor demands. These changes involved a design of new cornices and a significant reduction in a number of temporary supports so the structures had to be analyzed for the temporary construction states again. After completing all works on bridge deck and enabling operation of both tracks, the bridge reconstruction continued with reconstruction of the superstructure’s bottom face and existing parts of substructure including building-up of new pile caps.

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