scholarly journals On Stochastic Approach to Evaluation of Service Life for Reinforced Concrete Constructional Elements and Structures during Concrete Carbonization

2020 ◽  
Vol 19 (3) ◽  
pp. 241-251
Author(s):  
S. N. Osipov ◽  
V. M. Chik
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Concrete Structures ◽  
Calculated Data ◽  
Protective Layer ◽  
Stochastic Approach ◽  
Reinforced Concrete Structures ◽  
Reinforced Concrete Structure ◽  
Deterministic Models

The currently existing deterministic models for determination of structure service life do not take into account to the full extent variety of factors that have an effect on them and also stochastic characteristics of the used natural materials and conditions for manufacturing construction products, possible errors during the process of designing and construction etc. More trustworthy approach determining longevity and growth rate of destruction processes for structures in future periods can be obtained with the help of statistic methods that take into account a probabilistic essence of the process. The paper presents a possible approach of the probabilistic analysis on reinforced concrete structure service life while assessing rates of variation in depth growth of carbonization in a concrete protective layer on the basis of the existing experimental and calculated data pertaining to changes of the given index in reinforced concrete structures of various types. Variability of the existing approaches for determination of structure longevity as a whole has been shown firstly due to various number of basic vаriables used in calculations. Stochastic processing of the data on parameters of carbonization depth in the concrete protective layer has been carried out and this processing has made it possible to determine variation rates which allow to assess the presupposed service life of reinforced concrete structures having similar characteristics and being operated under analogous conditions. A definitive non-uniformity in statistic indices has been established that testifies about the necessity to increase accumulation of data on the investigated characteristics and to execute its processing more thoroughly. An expedience in usage of a concrete impermeability as a main factor determining its longevity has been established on the basis of statistical assessment of the existing data.

Zementgebundene Beschichtungen zum Schutz und zur Instandsetzung von Stahlbetonbauwerken / Protective and repair layers for concrete structures

2000 ◽  
Vol 6 (3) ◽  
pp. 243-272
Author(s):  
G. Martinola
Keyword(s):  
Reinforced Concrete ◽  
Ad Hoc ◽  
Protective Coatings ◽  
Concrete Structures ◽  
Autogenous Shrinkage ◽  
Protective Layer ◽  
Reinforced Concrete Structures ◽  
Reinforced Concrete Structure ◽  
Protective Layers ◽  
Shrinkage And Swelling

Abstract Cement based layers are frequently used during the repair of reinforced concrete structures nowadays. They restore the protection of the reinforcement against the penetration of aggressive substances. Protective coatings can also be applied to new structures in order to improve their durability. This paper discusses a concept for the improvement of durability of existing and new reinforced concrete structures using protective layers. To offer protection and to prevent the transport of harmful substances inside the reinforced concrete structure these layers have to be free from cracks during the planned service life. Under usual conditions such layers are submitted to different phenomena like thermal, hygral and autogenous shrinkage and swelling. These processes create a complex state of eigenstresses inside the system layer-subbase. The tensile stresses can lead to the formation of cracks and delamination of the protective layer after a few years. This paper suggests an approach for correct design of systems of protective as repair layers. For this purpose a numerical model is used in order to determine the time dependent stress distribution and the crack formation due to different loads and boundary conditions. On this basis the requirements for a layer can be formulated ad hoc as a function of the probabilistic properties of each damaged building and the risk of failure can be minimized.

scholarly journals Damage Assessment of Reinforced Concrete Elements Due to Corrosion Effect Using Dynamic Parameters: A Review

Buildings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 425
Author(s):  
Ivan Duvnjak ◽  
Ivan Klepo ◽  
Marijana Serdar ◽  
Domagoj Damjanović
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Protective Layer ◽  
Continuous System ◽  
Future Research ◽  
Reinforced Concrete Structures ◽  
Dynamic Parameters ◽  
Determination Methods ◽  
Concrete Elements

Corrosion of reinforcement is one of the main problems related to the durability of reinforced concrete structures. This can cause cracks and a separation of the protective layer, as well as reducing strength and structural stiffness, which can result in numerous human casualties. Visual inspection is a standard method of assessing the condition of reinforced concrete structures whose limitations, such as time, interpretability, accessibility, etc., may affect its effectiveness. Therefore, damage determination methods based on dynamic parameters are becoming more and more prominent in the assessment of damage to reinforced concrete structures. The aim of this paper is to review the literature regarding the determination of corrosion of reinforcement by methods based on dynamic parameters, and to identify future research to develop a method that would detect corrosion problems in time through a continuous system of structural health monitoring.

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.

EXPERIMENTAL STUDIES OF REINFORCED CONCRETE STRUCTURES WITH CROSS-SHAPED SPATIAL CRACK UNDER TORSION WITH BENDING

2020 ◽  
Vol 92 (6) ◽  
pp. 13-25
Author(s):  
Vl.I. KOLCHUNOV ◽  
◽  
A.I. DEMYANOV ◽  
M.M. MIHAILOV ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Experimental Determination ◽  
Calculation Method ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Design Parameters ◽  
Reinforced Concrete Structures ◽  
Experimental Scheme

The article offers a method and program for experimental studies of reinforced concrete structures with cross-shaped spatial crack under torsion with bending, the main purpose of which is to check the design assumptions and experimental determination of the design parameters of the proposed calculation method. The conducted experimental studies provide an opportunity to test the proposed calculation apparatus and clarify the regularities for determining deflections, angles of rotation of extreme sections, and stresses in the compressed zone of concrete. For analysis, the article presents a typical experimental scheme for the formation and development of cracks in the form of a sweep, as well as characteristic graphs of the dependence of the angles of rotation of end sections.

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