scholarly journals STRESS STATE OF COMPRESSED REINFORCED CONCRETE ELEMENTS CONSIDERING CREEP AND INFLUENCE OF AN AGGRESSIVE ENVIRONMENT

2021 ◽  
Vol 3 (1) ◽  
pp. 72-82
Author(s):  
M. Bekirova ◽  
Keyword(s):  
Reinforced Concrete ◽  
Strain State ◽  
External Environment ◽  
Reinforced Concrete Structures ◽  
Term Strength ◽  
Aggressive Environment ◽  
Theory Of Aging ◽  
The Impact ◽  
Concrete Elements

Problems associated with the joint long-term action of load and aggressive environment, both in limiting and over-limiting states, are studied bad. Such a combination leads to degradation of materials and changes in the stress-strain state of reinforced concrete structures over time. In case of joint action, they can have mutually increasing damaging effect. Among the many environmental influences encountered, the most aggressive in relation to concrete on cement binder is the impact of sulfates, and in relation to steel reinforcement – the impact of chlorides. It is shown that the stress-strain state of reinforced concrete compressed elements with regard to creep and influence of aggressive environment is formed in time. The deformation in concrete and reinforced concrete compressed elements depends on the stress level. If the stresses are less than the long-term strength, the deformations in time are attenuated, when the stresses in concrete are greater than the long-term strength, the deformations increase. Reinforcement restrains deformations in concrete, while corrosive medium increases creep deformations. When solving these problems we encounter internally statically indeterminate systems. The degree of static indeterminacy is greater than in the case of calculation of reinforced concrete structures without taking into account the influence of the external environment. When the process of soaking is considered, it is possible to consider the influence of the external environment as not aggressive. A solution to the problem using the theory of elastic heredity has been obtained, but it can be shown that a solution using other theories - the theory of aging or the hereditary theory of aging - is also possible. The above solution is true for reinforced concrete elements exposed to external influences at a sufficiently mature age, which can be considered one year or more from the date of manufacture of the structure.

scholarly journals The Impact of the Agressive Acid Environment on RC Constructions

2020 ◽  
Vol 2 (1) ◽  
pp. 223-229
Author(s):  
Yaroslav Blikharskyy ◽  
Roman Khmil ◽  
Zinoviy Blikharskyy ◽  
Taras Shnal
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Strain State ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Aggressive Environment ◽  
Acid Environment ◽  
The Impact ◽  
Concrete Elements ◽  
Reinforced Concrete Corrosion

AbstractThe main issue of the article is the corrosion of the reinforced concrete elements by the co-influence of the aggressive and power factors. The problem of corrosion is ex-tremely actual one. Therefore the tests were carried out upon the specimens considering the corrosion in the acid environment, namely 10 % H2SO4. The acid environment H2SO4 was taken as a model of the aggressive environment. Conclusions concerning the corrosion model of the cross section and investigation of stress-strain state have been made. That material concerns the problem of the reinforced concrete corrosion as a whole construction. Reinforced concrete beams were tested with and without the co-action of the aggressive environment and power factor.

scholarly journals Estimation of the pull-off resistance models of reinforced concrete structures by a numerical method

2021 ◽  
Vol 350 ◽  
pp. 00011
Author(s):  
Mikalai Shalabyta ◽  
Elizabeth Matweenko ◽  
Nikifor Matweenko ◽  
Valery Rakhuba
Keyword(s):  
Numerical Modeling ◽  
Reinforced Concrete ◽  
Comparative Analysis ◽  
Strain State ◽  
Numerical Models ◽  
Tensile Force ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
New Information ◽  
Concrete Elements

Comparative analysis of calculations of calculation numerical models for pulling out embedded parts in reinforced concrete structures is carried out. Based on the results of numerical modeling, new information about the stress-strain state in reinforced concrete elements from the local action of the tensile force has been obtained.

scholarly journals Long-term Influence of Concrete Surface and Crack Orientation on Self-healing and Ingress in Cracks – Field Observations

2018 ◽  
Vol 58 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Tobias Danner ◽  
Mette Rica Geiker
Keyword(s):  
Reinforced Concrete ◽  
Concrete Surface ◽  
Reinforced Concrete Structures ◽  
Chloride Ingress ◽  
Field Observations ◽  
Self Healing ◽  
Crack Orientation ◽  
Horizontal Orientation ◽  
The Impact

Abstract This paper presents results from investigations on the long-term influence of concrete surface and crack orientation on ingress in cracks. Five reinforced concrete structures from Norway exposed to either de-icing salts or seawater have been investigated. Concrete cores were taken with and without cracks from surfaces with vertical and horizontal orientation. Carbonation in cracks was found on all de-iced structures, and a crack on a completely horizontal surface appeared to facilitate chloride ingress. Ingress of substances from seawater was found in all cracks from marine exposure. However, the impact of cracks on chloride ingress was unclear. Horizontal cracks on vertical surfaces appeared to facilitate self-healing.

scholarly journals Nonlinear design model of reinforced concrete in terms of triaxial deformation

2018 ◽  
Vol 193 ◽  
pp. 03021
Author(s):  
Mikhail Berlinov ◽  
Artem Grigorjan
Keyword(s):  
Reinforced Concrete ◽  
Strain State ◽  
Load Capacity ◽  
Triaxial Stress ◽  
Reinforced Concrete Structures ◽  
Triaxial Deformation ◽  
Triaxial Stress State ◽  
High Rise ◽  
Nonlinear Design ◽  
Concrete Elements

The influence of reinforcement in the concrete work in the conditions of triaxial stress state high-rise construction is considered. The basic phenomenological resolving equations in a triaxial stress-strain state under vibration effects were developed for the calculation of reinforced concrete elements working with and without cracks in terms of nonlinearity and rheology of concrete deformation. A method for linearizing a problem based on integral estimates is proposed, which provides for the fixation of the creep processes in the considered period of time. The implementation of this method will allow us to find a numerical solution of the problem. Such an approach in the design of reinforced concrete structures will allow not only more fully taking into account the real conditions of their work, revealing additional reserves of load capacity, but also opening additional opportunities for analysis and forecasting their functioning at various stages of operation.

Stress-strain state of corrosion-damaged reinforced concrete elements under dynamic loading

2019 ◽  
pp. 19-26
Keyword(s):  
Reinforced Concrete ◽  
Strain State ◽  
Concrete Beam ◽  
Reinforced Concrete Beam ◽  
Stress Strain ◽  
Static Loads ◽  
Software Complex ◽  
Stress Strain State ◽  
The Impact ◽  
Concrete Elements

The solution of problems of survivability of reinforced concrete elements at beyond design impacts caused by simultaneous manifestation of power and environmental factors is necessary in modern realities. The impact of external aggressive environments, the operation of buildings without timely repairs is the cause of corrosion processes in reinforced concrete elements, which leads to a decrease in their bearing capacity and, as a consequence, reduction in the life of buildings. Currently, one of the urgent problems is the actual work of corrosion-damaged reinforced concrete elements under the impact of dynamic and static loads. The bendable reinforced concrete beam locally damaged in the compressed part of the cross-section is considered. Using modern computing software complex, it was carried out the comparative evaluation of the stress-strain state of an undamaged and corrosion-damaged reinforced concrete elements under dynamic and static loading. The influence of the weakened by corrosion concrete part of the compressed area on the redistribution of stresses in the section is analyzed.

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

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.

scholarly journals Long-Term Concrete Shrinkage Influence on the Performance of Reinforced Concrete Structures

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 254
Author(s):  
Alinda Dey ◽  
Akshay Vijay Vastrad ◽  
Mattia Francesco Bado ◽  
Aleksandr Sokolov ◽  
Gintaris Kaklauskas
Keyword(s):  
Reinforced Concrete ◽  
Reinforced Concrete Structures ◽  
Tension Stiffening ◽  
Model Code ◽  
Concrete Shrinkage ◽  
Time Period ◽  
Governing Factor ◽  
Model Code 2010 ◽  
Mathematical Process

The contribution of concrete to the tensile stiffness (tension stiffening) of a reinforced concrete (RC) member is a key governing factor for structural serviceability analyses. However, among the current tension stiffening models, few consider the effect brought forth by concrete shrinkage, and none studies take account of the effect for very long-term shrinkage. The present work intends to tackle this exact issue by testing multiple RC tensile elements (with different bar diameters and reinforcement ratios) after a five-year shrinking time period. The experimental deformative and tension stiffening responses were subjected to a mathematical process of shrinkage removal aimed at assessing its effect on the former. The results showed shrinkage distinctly lowered the cracking load of the RC members and caused an apparent tension stiffening reduction. Furthermore, both of these effects were exacerbated in the members with higher reinforcement ratios. The experimental and shrinkage-free behaviors of the RC elements were finally compared to the values predicted by the CEB-fib Model Code 2010 and the Euro Code 2. Interestingly, as a consequence of the long-term shrinkage, the codes expressed a smaller relative error when compared to the shrinkage-free curves versus the experimental ones.

Long-Term Deformations of Strengthened Reinforced Concrete Linear Elements

2016 ◽  
Vol 691 ◽  
pp. 51-60 ◽  
Author(s):  
Martin Krizma ◽  
Lubomir Bolha
Keyword(s):  
Reinforced Concrete ◽  
Long Term Results ◽  
Short Term ◽  
Limit States ◽  
Linear Elements ◽  
Repeated Load ◽  
The Moment ◽  
Concrete Elements ◽  
Fiber Fabric

The issue of strengthening the damaged linear reinforced concrete elements have been engaged since 2008. We focused on the analysis of resistance and the characteristics of limit states of serviceability in the damaged and subsequently strengthened elements at a short-term loading. In the introduction phase, the strengthening of the elements was carried out with the following procedures – installation of an overlayer on the coupling board or a combination of the board and use of glass – fiber fabric (GFRP). The strengthening was also affected by the type of contact (reinforced/non-reinforced) – the deformed element/coupling board and its effect on resistance, type of deformation and serviceability. In the non-reinforced contact, we applied some of the types of adjustments to the surface of the strengthened element. At the moment, we are dealing with the effects of time and repeated load on the strengthened elements. The results correspond to the reinforced contact. The values are compared with the short-term results of the strengthened beams and with the long-term results of the beams prepared for strengthening.

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