scholarly journals The Mechanical Properties of Centrifuged Concrete in Reinforced Concrete Structures

2020 ◽  
Vol 10 (10) ◽  
pp. 3570
Author(s):  
Romualdas Kliukas ◽  
Ona Lukoševičienė ◽  
Arūnas Jaras ◽  
Bronius Jonaitis
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Concrete Strength ◽  
Concrete Structures ◽  
High Strength ◽  
Reinforcement Ratio ◽  
Transverse Reinforcement ◽  
Reinforced Concrete Structures ◽  
Test Results ◽  
Moduli Of Elasticity

This article explores the influence of transverse reinforcement (spiral) and high-strength longitudinal reinforcements on the physical-mechanical properties of centrifuged annular cross-section elements of concrete. The test results of almost 200 reinforced, and over 100 control elements are summarizing in this article. The longitudinal reinforcement ratio of samples produced in the laboratory and factory varied from 1.0% to 6.0%; the transverse reinforcement ratio varied from 0.25% to 1.25%; the pitch of spirals varied from 100 mm to 40 mm and the concrete strength varied from 25 MPa to 60 MPa. Experimental relationships of coefficients for concrete strength, moduli of elasticity and limits of the longitudinal strain of centrifuged concrete in reinforced concrete structures in short-term concentrically compression were proposed.

scholarly journals Strength Calculation Features and Tests Results on Bearing Capacity and Operational Serviceability of Hollow-Core Floor Slabs of Formwork-Free Shaping in Seismic Areas

2020 ◽  
Vol 9 (1) ◽  
pp. 2219-2225
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Construction Industry ◽  
Precast Concrete ◽  
Concrete Strength ◽  
Concrete Structures ◽  
High Strength ◽  
Reinforced Concrete Structures ◽  
Hollow Core ◽  
Wide Range

The technology of manufacturing reinforced concrete structures of long-line systems of formwork-free shaping is widely used lately in construction industry in many countries. Using this technology, industrial construction can be carried out in accordance with the requirements of modern regulatory documents that allow projects to be developed individually, and production can be reoriented in a very short time in accordance with emerging needs. This means that on the same production line it is possible to produce various structural elements of buildings and structures. Also, this technology allows the production of structures according to a wide range of products that meet operational requirements, and increases the possibility of their use in design of buildings and structures with various architectural, planning and structural decisions. Prestressed hollow-core slabs of formwork-free shaping reinforced with high-strength wire reinforcement are widely used due to the simplicity of construction and their relatively low cost, as well as their high bearing capacity, large spans and better quality. The problem of their introduction into construction industry of Uzbekistan is that the issues of designing, manufacturing and using them in construction have not been studied. Besides, the production technology of such slabs is mostly associated with the construction in non-seismic areas, and the country does not have an appropriate regulatory framework for the possibility of slab designing and production. The aim of the study is to assess the strength and serviceability of hollow-core slabs of formwork-free shaping, designed on the basis of the proposed structural solution of the slab cross section and intended for construction in seismic areas. Therefor the issues of optimizing the main reinforcement consumption (prestressed high-strength wire reinforcement) at class B30 concrete strength without using the non-stressed reinforcement (reinforcing products) for the product range under consideration were addressed. Theoretical and constructive solutions of the slabs were developed in accordance with the standard requirements of Uzbekistan KMK 2.03.01-96 “Concrete and reinforced concrete structures”, KMK 2.01.03 “Construction in seismic areas” and considering the Euronorm EN 1168-2005 requirements “Precast concrete. Hollow-core slabs”.

scholarly journals Effects of Tension Reinforcement Ratio on Ductility of Mid-Rise Reinforced Concrete Structures

2018 ◽  
Vol 1 (1) ◽  
pp. 702-708
Author(s):  
Onur Onat ◽  
Burak Yön
Keyword(s):  
Reinforced Concrete ◽  
Failure Mode ◽  
Concrete Structures ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Structures ◽  
Rc Structures ◽  
Beam Elements ◽  
First Case ◽  
Rc Structure ◽  
Determine Effect

Failure mode of reinforced concrete (RC) structures are classified according to tension reinforcement ratio of beam elements. To determine effect of tension reinforcement ratio on performance of RC structure, two planar RC structure were selected. One of them is 5 stories other of them is 7 stories. Two different concrete class, C20 and C25, were considered for analysis. Three tension reinforcement combinations were considered, three different tension reinforcement ratios were used. First case is the ratio of the tension reinforcement is lower than that of the compression reinforcement, second case is the ratio of the tension reinforcement is equal to the ratio of the compression reinforcement and third case is the ratio of the tensile reinforcement is higher than the compression reinforcement.

scholarly journals Corrosion protection of reinforcing steel reinforced concrete structures of transport structures

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Alexander Bulkov ◽  
Michail Baev ◽  
Igor Ovchinnikov
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Protection ◽  
Concrete Structures ◽  
Steel Corrosion ◽  
High Strength ◽  
Curing Temperature ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Steel Reinforced Concrete ◽  
Advantages And Disadvantages

The influence of reinforcing steel corrosion on the durability of reinforced concrete structures of transport structures and the degree of knowledge of this problem is considered. It is specified that the protection of reinforcing steel from corrosion is not able to completely replace the correct design and use of high-strength concrete. But it is able to extend the life of reinforced concrete structures. It is noted that corrosion of the reinforcement leads to a decrease in the structural strength due to wear and tear and by a third of the period of operation of reinforced concrete structures, as a result of which transport structures collapse. As an example of the detrimental effect of corrosion of reinforcing steel on the durability of transport structures, examples of accidents of bridges and overpasses caused by this type of corrosion are given. As a result, a conclusion is drawn on the advisability of ensuring a sufficient level of corrosion protection of reinforcing steel to achieve the required durability of reinforced concrete structures of transport structures. The types and causes of corrosion processes in reinforcing steel reinforced concrete structures are described. The compositions and technologies of anticorrosive protection are examined and analyzed. Comparison of the compositions of anticorrosive protection of reinforced concrete structures is carried out according to the following criteria: consumption, density, viability, curing temperature and the number of components of the composition. A comparison of anti-corrosion protection technologies is carried out on the basis of the following indicators: line dimensions, productivity and consumption of energy resources. A comparison is also made of the cost of using various anti-corrosion protection technologies. Based on the data obtained, the advantages and disadvantages of the considered compositions and technologies of corrosion protection are determined. As a result, the most effective and technologically advanced method of corrosion protection of steel reinforcement of reinforced concrete structures of transport structures is selected.

scholarly journals Experimental study of the influence of crack width due to corrosion behaviour using different measurement methods and different exposures

2019 ◽  
Vol 289 ◽  
pp. 08005
Author(s):  
Martin Schneider ◽  
Georg Gardener
Keyword(s):  
Reinforced Concrete ◽  
Crack Width ◽  
Corrosion Behaviour ◽  
Concrete Strength ◽  
Concrete Structures ◽  
Chloride Ions ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Surface Corrosion ◽  
Potential Mapping

Corrosion of reinforcing steel has a great influence in reducing the lifetime of concrete structures; Carbonation of the concrete pore solution causes surface corrosion on the steel and diffusion of chloride ions through the capillary system of the concrete cover causes pitting corrosion on the steel surface. Corrosion of metals is highly dependent on the environmental conditions. Exposure to chloride ions can be critical to the service life of reinforced concrete structures. The durability of reinforced concrete structures exposed to deicing salt or marine environments can be affected by impact of chloride ions. Detection methods for the rate of corrosion of non-destructive and destructive procedures were analysed. The potential mapping applied on the concrete surface was discussed as a standard method for corrosion detection and will be explained in detail including the application boundaries of the method. It is assumed that the corrosion behaviour of reinforcing steel depends on crack widths. To analyse that, 8 coated and 8 uncoated test samples with different concrete strength classes were used. The concrete objects were exposed to a 3% sodium chloride solution. The corrosion behaviour of reinforcing steel is analysed by using potential mapping with different reference electrodes (Ag/AgCl and Cu/CuSO4). The results show a significant correlation between crack size and protection system on the surface. The maximum crack width with a low indication of corrosion was found to be 0.1 mm.

Study on Seismic Behavior of Vertical Connection in Prefabricated Reinforced Concrete Structures

2011 ◽  
Vol 250-253 ◽  
pp. 1385-1394
Author(s):  
Guo Hua Song ◽  
Dong Wei Wang ◽  
Bing Kang Liu
Keyword(s):  
Reinforced Concrete ◽  
Seismic Behavior ◽  
Concrete Structures ◽  
Shear Resistance ◽  
Repeated Loading ◽  
Reinforced Concrete Structures ◽  
Test Results ◽  
Dowel Action ◽  
Cycle Loading ◽  
Good Agreement

The paper attempts to research the seismic behavior and mechanical mechanisms under repeated low-cycle loading of vertical connections in prefabricated reinforced concrete structures. Eighteen specimens were designed and tested, the test process and the mechanical mechanisms are studied, the seismic behavior of connections is analyzed, and the shear resistance formulas are proposed. The theoretical values based on proposed formulas are good agreement with test results. Under repeated loading, the shear resistance decreases, the connection ductility increases with connecting bar, but decreases with connection width. However, all the connections fail crisply with poor ductility. At sudden-cracking, the shear resistance increases with connecting bar, but changes nonlinearly with connection width. The resistance is composed of attributions of mechanism of diagonal-compressive column (MDCC) and mechanism of compressive friction action (MCFA). After sudden-cracking, the shear resistance is provided by weakened MDCC and dowel action of connecting bars (DACB). It increases with connecting bar and connection width.

scholarly journals Historical reinforced concrete structures – used materials and calculating algorithms

2015 ◽  
Vol 14 (2) ◽  
pp. 105-112 ◽  
Author(s):  
Bartosz Szostak ◽  
Maciej Trochonowicz
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Structural Element ◽  
Historical Building ◽  
Historical Material ◽  
Low Strength ◽  
Concrete Elements

During designing in historical object we can have a problem with historical reinforced concrete elements. Many designers, classifies this elements as low strength. They are convicted that this type of elements in historical building can be only a monument and cannot be used in this construction as an structural element. It is very important in this type of buildings to keep as many historical material as it is possible. Authors researched the literature which has been a guide in the design and execution of these elements. By comprising used algorithms and physico-mechanical properties of old materials with algorithms and materials, which are using today, we are able to estimate the strength of such elements.

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