scholarly journals Possibility of application of concrete sleeper with under sleepers pads

Author(s):  
Zvonko Perčin

One of the most sensitive segments of the railway infrastructure are certainly bridges. All steel grid bridges have wooden sleeper attached to the bridge structure and cannot change the height when maintaining the upper structure rails. It has become a practice to reconstruct or replace damaged bridges in the past by taking care that the track construction is separated from the bridge constructions. One way is that steel grid structures are replaced with reinforced concrete structures in the form of a trough or if the spans are larger with steel structures in the form of a trough. The standard classical track construction today is a gangway with concrete sleepers and a ballast of crushed stone material. Such tracks have reduced elasticity, which is particularly important at contact between the sleepers and the stone material. In order to reduce the negative impacts of vibration and thus extend the durability of railway track today, railways increasingly apply concrete sleepers with under sleepers pads. Tests have shown that with the installation of the under sleeper pads it is possible to achieve a quieter passage of the train over the substrates of different stiffness, thus reducing the possibility of damage to the track construction and the vehicle itself.

2018 ◽  
Vol 193 ◽  
pp. 02005
Author(s):  
Myhammet Fachratov

The methods of waste recycled usage, especially, usage of secondary crushed stone made of crushed concrete scrap are becoming ever more relevant with every passing year. Imported concrete aggregate volumes can be reduced by 15-30% due to usage of secondary crushed stone. Consideration of industrial waste problem and methods of solving this problem by using waste in construction industry including secondary crushed stone made of crushed concrete scrap. Annually, about 11.5 million tons of construction waste is generated in Moscow, in the near future concrete scrap volumes are expected to rise to 13-15 million tons per year because of building demolition, reconstruction, overhaul and piling of reject structures.


The problems considered within the frame of scientific and technical support are shown on the example of design and construction of a unique high-rise building of "Lakhta Center" in St. Petersburg. The main results of design support and construction of steel, steel-reinforced concrete structures, as well as structures made of laminated glass are presented. The main reason for atypical design and technological solutions for steel structures are thickness of rolled steel and the material of structures non-standard for domestic practice. In addition, there was no normative approach to the design of steel-reinforced concrete structures and structures made of laminated glass at the time of design of the complex. The tests carried out within the scientific and technical support provided the necessary information for the design of unique structures. It is required to develop the set of rules defining the requirements for scientific research when constructing unique objects for a more orderly scientific and technical support and justification of the amount of work performed.


Author(s):  
V.I. Golovanov ◽  
◽  
A.V. Pekhotikov ◽  
V.V. Pavlov ◽  
◽  
...  

Variants of progressive solutions for the use of efficient fire protection means for steel and reinforced concrete structures of the industrial buildings and structures are considered for the purpose of increasing the actual fire resistance and ensuring the requirements of fire safety norms. Distinctive features of the temperature regimes in the initial phase of a real fire from a standard fire were established when assessing the fire resistance of building structures. It is proposed to use such standardized temperature regimes of fire for assessing the fire resistance of building structures, as standard — in the industrial buildings; temperature regime of hydrocarbons combustion — for oil and gas, petrochemical enterprises, offshore stationary platforms; tunnel temperature regime — in the road and railway tunnels. Considering the operating conditions and performance of work on fire protection, the degree of aggressiveness of the environment, the structural and methodological scheme was developed for selecting passive fire protection for steel structures. Recommendations are given on limiting the use of intumescent paints for load-bearing steel structures involved in the overall stability of buildings, with the required fire resistance limit of no more than 30 minutes. To calculate the temperature over the section of the structure during its heating, the dependences of the change in the coefficients of thermal conductivity and heat capacity of fire-retardant linings under fire were obtained. Experimental studies were conducted related to the fire resistance of reinforced concrete floor slabs and slabs with an external reinforcement system based on the carbon composite material with various types of fire-retardant materials. The issue of protecting the lining blocks of road and railway tunnels from brittle (explosive) destruction of concrete in a fire is considered. It is experimentally confirmed that the addition of polypropylene fibers to the concrete mixture replaces the use of fire protection for the tunnels enclosing structures.


Author(s):  
Alexander M. Belostotsky ◽  
Pavel A. Akimov ◽  
Andrey A. Aul ◽  
Dmitry S. Dmitriev ◽  
Yulia N. Dyadchenko ◽  
...  

It is obvious that contemporary design and construction of unique buildings and structures is unthinkable without mathematical (numerical) and computer modelling and advanced analysis ofload-bearing structures under various kinds ofloads and impacts. One of the most ambitious and important construction projects is the uniquelarge-span structures. These are, in particular, stadiums, sports palaces and water parks, shopping malls, pedestrian, road and railway bridges of various design solutions. The distinctive paper is devoted to theoretical foundations and results of mathematical (numerical) modeling of the state (in terms of the analysis of stress-strain state, strength and stability) of football stadiums built for the 2018 FIFA World Cup in Russia. Finite element method is used for approximation and high-precision numerical solution of corresponding boundary problems of structural mechanics. It is the most universal and powerful numerical method of mechanics. The paper, in particular, describes some features of development of finite element models and the main results of the analysis of the mechanical (structural) safety of three- dimensionallarge-span systems "soil foundation - reinforced concrete structures of foundations and stands - steel structures of the coating and facades" of these football stadiums with the basic and specialload combinations. In addition, the key procedures of scientific support during the corresponding expertise and assessments are outlined. Generally, socially significant and knowledge-intensive problem of providing mechanical (constructive) safety of unique combined objects of construction (three-dimensional systems "foundation - reinforced concrete structures of foundations and stands - steel structures of coating and facades") has been solved at a new level as a result of the performed complex of research works.


2019 ◽  
Vol 2 (2) ◽  
pp. 79
Author(s):  
Inggrid Loiza Batak ◽  
Safrin Zuraidah ◽  
Budi Hastono

Recently, a structure that is generally applied to the construction of multi-storey buildings is reinforced concrete structure. Structural steel is rarely used nowadays, yet in fact, the steel structures are still able to compete with reinforced concrete structures. Therefore, this study aims to determine the exact profile dimensions and the comparison of material prices between steel structures and reinforced concrete structures for columns and beams in redesigning H Building of Dr. Soetomo University, Surabaya. The WF profile steel will be used in this redesigning project. The structure is modeled using AutoCAD, and then imported into SAP2000 software. Modeling structure consists of columns, primary beams and secondary beams. The loads reviewed from the design are dead load, live load, wind load and seismic load. From the results of design review obtained, the overall strength of structure rearrangement is safe and it is obtained the beam profile dimensions of B1 WF 600x200x12x20, B2 WF 400x300x9x14 profile, B3 WF 400x300x9x14 profile, B4 WF 350x200x8x12 profile, and B5 WF 175x125x 5.5x8 profile, K1 WF 400x400x18x28 column profile, and K2 WF 400x400x21x21 column profile. The use of steel structures as a substitute for reinforced concrete structures for columns and beams in the building is a way more expensive with the percentage of steel structure 149.13% more expensive than reinforced concrete structure.


2014 ◽  
Vol 7 (3) ◽  
pp. 329-348 ◽  
Author(s):  
D. M. Oliveira ◽  
N. A. Silva ◽  
P. M. Oliveira ◽  
C. C. Ribeiro

This paper presents an alternative to estimate the magnifier of first order moments to be applied on each storey of reinforced concrete structures, from the values obtained for the γz and B2 coefficients, used to evaluate second order effects in reinforced concrete structures and in steel structures, respectively. In order to develop the study, initially several reinforced concrete buildings of medium height are processed, in first order and in second order, using the ANSYS software. Next, γz, B2 and the increase in first order moments, when considering the second order effects along the height of the buildings, are calculated. Finally, from the results obtained, the magnifier of the first order moments, differentiated for each storey of the structure and calculated from both γz and B2 coefficients, is estimated and the efficiency of the simplified method of obtaining final moments using the magnifier proposed is evaluated.


Author(s):  
Hala Tawfek Hasan, Khaled Al-Homsi Hala Tawfek Hasan, Khaled Al-Homsi

This study discusses the effect of metallic yielding dampers (ADAS) on the behavior of reinforcement concrete buildings when exposed to seismic shocks. The objective of the study is to reduce the negative impacts on the main structural elements (plastic, fall) by using the technique of metallic dampers. The method of metallic dampers is one of the modern ways based on the principle of dissipating the resulting energy from the seismic shock and reducing the needed energy in the main structural elements of the building to keep it in a flexible state. This technique also provides a controlling mechanism for story displacement, the handling of the soft story mechanic and the torsion mechanic of the buildings. In this study, the effect of the addition of ADAS dampers on the construction behavior was observed in terms of (building period, base shear, roof displacement, roof acceleration, story displacement, dissipative energy). Based on the preceding, this study will give the possibility of predicting the behavior of the building when using ADAS metal dampers in the reinforced concrete structures with their distribution methods.


Author(s):  
Mohammad Ali Asaad ◽  

Civil construction projects have always met with corrosion issues affecting reinforcements, both in circumstances where the relevant standards were not observed during concrete design and preparation and in structures close to bridges, coasts, ports, quays and so on, where exposure to an aggressive environment can lead to damage such as rust spots, cracking and delamination of the concrete cover, which constitutes a hazard for the end-user. Inhibitors are frequently simple to apply and extensively utilised to reduce the corrosion rate of many steel structures in the aggressive environments without causing any significant disruption to the process. The article reviews information related to the mechanism of corrosion prevention methods to increase the service life of structures in coastal areas. This is included commercial inhibitors (inorganic and organic), sealers and barriers, eco-friendly inhibitor, and green inhibitor combined with nanoparticles. An analysis of the published literature demonstrates a general agreement that one of the most significant problems affecting reinforced concrete structures is corrosion of the steel reinforcements.


Currently, prefabricated reinforced concrete structures are widely used for the construction of buildings of various functional purposes. In this regard, has been developed SP 356.1325800.2017 "Frame Reinforced Concrete Prefabricated Structures of Multi-Storey Buildings. Design Rules", which establishes requirements for the calculation and design of precast reinforced concrete structures of frame buildings of heavy, fine-grained and lightweight structural concrete for buildings with a height of not more than 75 m. The structure of the set of rules consists of eight sections and one annex. The document reviewed covers the design of multi-story framed beam structural systems, the elements of which are connected in a spatial system with rigid (partially compliant) or hinged joints and concreting of the joints between the surfaces of the abutting precast elements. The classification of structural schemes of building frames, which according to the method of accommodation of horizontal loads are divided into bracing, rigid frame bracing and framework, is presented. The list of structural elements, such as foundations, columns, crossbars, ribbed and hollow floor slabs and coatings, stiffness elements and external enclosing structures is given; detailed instructions for their design are provided. The scope of the developed set of rules includes all natural and climatic zones of the Russian Federation, except seismic areas with 7 or more points, as well as permafrost zones.


Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.


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