scholarly journals CRACK RESISTANCE OF REINFORCED CONCRETED AND REINFORCED RUBBER CONCRETE BEAMS

2020 ◽  
Vol 1 (22) ◽  
Author(s):  
Artem Levchenko ◽  
Aleksei Polikutin ◽  
Dmitry Barabash
Keyword(s):  
Tensile Strength ◽  
Reinforced Concrete ◽  
Crack Resistance ◽  
Voltage Drop ◽  
Concrete Structures ◽  
Polymer Concrete ◽  
Reinforced Concrete Structures ◽  
Longitudinal Reinforcement ◽  
Structural Element ◽  
Concrete Body

The issue of the appearance and development of cracks, as well as an increase the cracking moment is of particular importance for bending elements operating under aggressive environmental conditions. In structures without cracks, steel reinforcement operates in fairly favorable conditions. However, when cracks appear in the sections of the structural element, the reinforcing bar is exposed to aggressive environmental influences, the voltage drop across the reinforcement also increases, etc.In reinforced concrete structures, tensile stresses are perceived by reinforcing bars, an increase in the content of longitudinal reinforcement in the section leads to some increase in crack resistance of structures, however, an increase in the percentage of longitudinal reinforcement causes a number of undesirable phenomena such as increased consumption of reinforcement and increased weight of the structure. Also, the introduction of reinforcement into the concrete body does not eliminate such disadvantages of concrete as susceptibility to corrosion, low elasticity, low tensile strength and tensile strength. The use of polymer concrete improves these properties of reinforced concrete structures, while the density of fiber rubcon and rubcon is slightly lower than that of traditional concrete, and, consequently, the weight of structures made of this polymer concrete.

scholarly journals FLEXURAL REINFORCED CONCRETE ELEMENTS NORMAL SECTION BEARING CAPACITY EVALUATION IN FRACTURE STAGE

2017 ◽  
Vol 9 (2) ◽  
pp. 70-78 ◽  
Author(s):  
Justas SLAITAS ◽  
Zbynek HLAVAC ◽  
Arnoldas ŠNEIDERIS
Keyword(s):  
Tensile Strength ◽  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Crack Depth ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Assessment Process ◽  
Reinforced Concrete Structures ◽  
Compression Zone ◽  
Normal Section

This article examines flexural reinforced concrete structures condition assessment process in existing buildings on the stage where the reinforcement stress is between the yield and the tensile strength. The research is made on V. Jokūbaitis proposed methodology directly measuring the compression zone height, allowing us to evaluate the behavior of reinforced concrete beam fracture sufficiently precisely. This paper confirms the hypothesis that, when reinforcement reaches yielding stress, elastic strain dominates in concrete‘s compression zone and it is reasonable to use triangular concrete compression zone diagram, without tensile concrete above crack evaluation. The methodology of reinforced concrete structures bearing capacity assessment according to limit normal section crack depth is proposed. There is established connection between bending moments, when reinforcement achieve yielding stress and tensile strength, which allows us to decide about structures bearing capacity reserve. The results are confirmed with experimental studies and calculated values obtained by methodologies based on different reduced stress diagrams of concrete‘s compressive zone.

scholarly journals Investigation of the relationship between the strength limit and the long time fatigue of steel reinforcements of reinforced concrete structures

2021 ◽  
pp. 28-40
Author(s):  
Denys Chernyshev ◽  
Yulia Makarenko ◽  
Tetiana Khomutetska ◽  
Valeriy Makarenko
Keyword(s):  
Reinforced Concrete ◽  
Crack Resistance ◽  
Hydrogen Content ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Term Operation ◽  
Strength Limit

The results of experimental studies have shown a strong effect of diffusion hydrogen on the static and cyclic parameters of crack resistance of reinforcing steel. It was found that with increasing flooding, especially when the hydrogen content exceeds 5 cm3/100g, both static strength and long-term strength (fatigue) decrease sharply. Moreover, these areas of hydrogen solution in reinforcing steel are characterized by a viscous nature of fracture, while for heavily flooded reinforcement (from 5 to 12 cm3/100g) is characterized by brittle fracture by the mechanism of microcracking in the hardened (martensite or troostite structure). The analysis of the obtained experimental results allowed to determine the optimal hydrogen content in the reinforcing steel (3…5 cm3/100g), the excess of which can cause a decrease in the crack resistance of the reinforcement during long-term operation, especially in corrosive environments. The mechanism of hydrogen influence on crack resistance of metal at static and alternating loading which consists in diffusion and dislocation movement of hydrogen in structure of a reinforcing core that as a result that causes strong flooding of steel and its embrittlement is offered. It is established that carbon and low-alloy sieves, which are characterized by ferritic-pearlitic and sorbitol structure provide high resistance, especially to long-term fatigue, and the transition to steels with a structure of martensite or tempered (transient structure of bainite) structure of bainite sharply reduces reinforcing steel, which makes it impossible to use in the manufacture of reinforcement involved in reinforced concrete structures designed for long-term operation (more than 50…60 years). Thus, the obtained diagram can be recommended to designers of reinforced concrete structures for hydraulic purposes, as it greatly facilitates the reasonable choice of reinforcement in the development of reinforced concrete structures for responsible and long-term use.

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.

scholarly journals Experimental study of beams on yielding supports with thrust

2018 ◽  
Vol 143 ◽  
pp. 01016
Author(s):  
Oleg Kumpyak ◽  
Zaur Galyautdinov ◽  
Daud Galyautdinov
Keyword(s):  
Reinforced Concrete ◽  
Crack Resistance ◽  
Dynamic Loading ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Horizontal Displacement ◽  
Positive Outcome ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Structures ◽  
Short Term

The design of reinforced concrete structures which are subjected to static and intensive dynamic loading requires taking into account the occurrence of thrust reaction resulting in significant increase in strength and crack resistance. Application of yielding supports for the purpose of increasing the energy capacity of structures shall also be considered. The present research aims to define feasibility of yielding supports application in thrust structures. The paper presents the outcomes of experimental studies of reinforced concrete beam structures on yielding supports subjected to thrust under static and short-term dynamic loading. The influence of thrust on the strength, deformation property and crack resistance of reinforced concrete structures under static and short-term dynamic loading was investigated. The combined use of yielding supports and the restriction of horizontal displacement of the support contour were also considered in the study. Research results testify on the positive outcome when yielding supports are applied in the structures subjected to thrust.

scholarly journals Construction of the interaction curve of concrete-encased composite columns based on the deformation domains of reinforced concrete sections

2015 ◽  
Vol 8 (4) ◽  
pp. 447-466 ◽  
Author(s):  
P. A. S. ROCHA ◽  
K. I. DA SILVA
Keyword(s):  
Reinforced Concrete ◽  
Computer Program ◽  
Axial Force ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Longitudinal Reinforcement ◽  
Limit Values ◽  
Composite Columns ◽  
Interaction Curves ◽  
The Moment

AbstractThis paper proposes a methodology for obtaining the interaction curve for composite steel-concrete sections subject to combined compression and bending based on the deformation domains of reinforced concrete structures defined by ABNT NBR 6118 [1]. For this, were developed expressions for the axial force, the moment and the strains of concrete, longitudinal reinforcement and the elements comprising the metal profile in each deformation domain.Based on these expressions a computer program called MDCOMP (2014) was created. In this study the same limit values of longitudinal reinforcement strain defined by ABNT NBR 6118 [1] were used for the steel profile strains. To verify the numerical implementations performed, the interaction curves and the plastic resistance of the section obtained by MDCOMP program were compared with those determined from the recommendations of Eurocode 4 [2], of ABNT NBR 8800 [3] or literature responses.

scholarly journals ANALYSIS OF THE MAIN FACTORS AFFECTING THE QUALITY OF RESTORATION WORK OF CONCRETE AND REINFORCED CONCRETE STRUCTURES

2021 ◽  
Vol 81 (3) ◽  
pp. 91-97
Author(s):  
B.M. Aubakirova ◽  
◽  
E.R. Onlasynov ◽  
Keyword(s):  
Tensile Strength ◽  
Reinforced Concrete ◽  
Adhesion Strength ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Factors Affecting ◽  
Restoration Work ◽  
Main Factors

This article examines the analysis of the main factors affecting the quality of the restoration work of concrete and reinforced concrete structures. The ways of increasing the capacity of repair concrete by increasing the adhesion strength are shown. As a result, its value should not be lower than the tensile strength of concrete.

scholarly journals Residual resource of force resistance to deformation

2019 ◽  
Vol 135 ◽  
pp. 01069 ◽  
Author(s):  
Vladimir Rimshin ◽  
Ekaterina Kuzina ◽  
Alexey Neverov
Keyword(s):  
Reinforced Concrete ◽  
Crack Resistance ◽  
Calculation Method ◽  
Residual Life ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Engineering Structures ◽  
Transverse Bending ◽  
Specific Loading ◽  
Complex Calculation

The problem of the durability of reinforced concrete structures of urban engineering structures is currently one of the urgent problems in modern construction due to the continuously growing volume of expensive repair and restoration work, facilities reconstruction, a tendency to a general decrease in quality requirements, and the scale of reinforced concrete structures application in difficult climatic conditions. The theoretical foundations of calculating the residual life of the force resistance to transverse bending with the strength of normal sections in the article, algorithms for calculating the residual life of the force resistance and reinforcement of corrosion-damaged reinforced concrete structures are defined. A complex calculation method is considered in this article that allows to quantitatively assessing the state and resources of crack resistance of reinforced concrete structures damaged by corrosion, to calculate the necessary levels of compression and loss of tension, as well as the exposure to preserve crack resistance in time at specific loading levels and intensities of corrosion effects. The developed complex calculation method can be presented as part of the solution to the problem of preventing and eliminating emergency situations. The theoretical basis for calculating the residual resource of strength resistance to transverse bending by the strength of inclined sections are discussed in the article, the calculation algorithms are studied, and examples are given.

scholarly journals Effect of corrosion degree on different steel ductility parameters, based on “Equivalent Steel” criterion

2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Esther Moreno ◽  
Alfonso Cobo ◽  
Maria Nieves Gonzalez
Keyword(s):  
Tensile Strength ◽  
Reinforced Concrete ◽  
Design Methodology ◽  
Linear Models ◽  
Concrete Structures ◽  
Steel Corrosion ◽  
Reinforced Concrete Structures ◽  
Accelerated Corrosion ◽  
Rc Structures ◽  
Standing Structure

Purpose One of the meaningful effects of concrete reinforcement steel corrosion on concrete structures is the decrease of mechanical properties, specifically the ductility of steel. The term ductility of steel refers to a group of properties which determine the reinforced concrete structures and it is necessary to take this property into account for the recalculation of structures that have been already corroded until the point to condition in many occasions the analysis methodology. Design/methodology/approach This research studies the variation on ductility of concrete embedded steels bars after going through an accelerated corrosion process. Tensile strength of high ductility reinforcements with different corrosion levels has been tested. Ductility was studied in terms of ultimate tensile strength, yield strength, ultimate strain, energy density of deformation and “equivalent steel” criterion. It also makes some considerations about what is the best methodology of structural analysis according to the obtained results. Findings Based on the obtained results, conclusions are established that determine whether the corroded steel satisfy the requirements of different codes in order to identify them as “steels with special characteristics of ductility” assessing in each case the possibility of reallocating solicitations in structures which might need to be repaired. Originality/value The analysis of existing RC structures should address moment redistribution to be able to compare ultimate strength values, rather than to a single value obtained with elastic linear models to a range of values centred on the elastic and linear values obtained and defining an interval equal to double the value of the maximum redistribution capacity. This greatly enhances the possibility of “saving” a standing structure. In ductile structures the effect of actions can be distributed. The ascertainment of corroded reinforcement ductility variation is of key importance in structural re‐engineering and recalculation of structures. The research developed in this article is motivated by the need to contribute to knowledge of the behavior of reinforced concrete structures with reinforcement damaged.

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