scholarly journals Calculation of the crack resistance of reinforced concrete elements with allowance for the levels of normal crack formation

2018 ◽  
Vol 230 ◽  
pp. 02028 ◽  
Author(s):  
Vasyl Romashko ◽  
Olena Romashko
Keyword(s):  
Reinforced Concrete ◽  
Crack Resistance ◽  
Calculation Method ◽  
Solid Mechanics ◽  
Crack Formation ◽  
Crack Opening ◽  
Nonlinear Function ◽  
Experimental Investigations ◽  
Concrete Element ◽  
Concrete Elements

The separate experimental investigations results and the major drawbacks of existing methods of calculating the reinforced concrete elements crack resistance are considered in detail, taking into account the process of multilevel formation and crack opening. Based on the basic provisions of the deformation and strength model of concrete and reinforced concrete resistance, an engineering method for calculating the formation and disclosure of normal cracks in the reinforced concrete elements and structures at the operational stages of their deformation is proposed. It is implemented on the system of generally accepted static, geometric and physical relations of a deformed solid mechanics. The simplicity of the proposed calculation method is due to the use of the nonlinear function of the average stresses of the reinforcement bond with concrete on the sections of the reinforced concrete element between adjacent cracks. The main advantages of the developed calculation method in comparison with others are outlined.

scholarly journals Model of normal cracks level formation and opening in stretched reinforced concrete elements

2021 ◽  
pp. 28-36
Author(s):  
Olena Vasylivna Romashko-Maistruk ◽  
Vasyl Mykolayovych Romashko
Keyword(s):  
Reinforced Concrete ◽  
Crack Formation ◽  
Crack Opening ◽  
Nonlinear Function ◽  
Load Level ◽  
Direct Integration ◽  
Test Results ◽  
Advantages And Disadvantages ◽  
Concrete Elements ◽  
Opening Width

The article highlights the most important studies results of the mechanism of normalcracks formation and opening in stretched reinforced concrete elements during their deformation. Acritical analysis of the existing methods and ways for calculating normal cracks level formation andopening, in which the reinforcement to concrete adhesion is taken into account directly or indirectly,is carried out. The main advantages and disadvantages of each of these methods are indicated. It hasbeen experimentally confirmed that the crack formation process is generally leveled. The mainfeatures and patterns of cracking in stretched reinforced concrete elements and structures arerevealed. The main characteristics of the prototypes are given, according to the test results of whichit was established that in practical calculations of the reinforced concrete elements crack resistance,it is usually possible to restrict oneself to two levels of normal cracking. For the indicated crackinglevels, the corresponding load level, step and crack opening width are established. The expediencyof using in practical calculations the nonlinear function of the reinforcement with concrete averageadhesion stresses is also substantiated. Based on the studies results carried out, the existing methodsfor calculating the normal cracks formation and opening in reinforced concrete elements andstructures were evaluated from the standpoint of local disadvantage of the reinforcement to concreteadhesion.General and simplified methods for calculating normal cracks level formation and opening inreinforced concrete elements have been developed. In them, the direct integration of the expressionfor the concrete and reinforcement mutual displacements is proposed to be replaced not by thenumerical integration of the indicated expression, but by the successive accumulation of the indicateddisplacements. Corresponding statistical comparisons of the calculations results by these methodswith experimental data are carried out. The effectiveness of the developed methods for calculatingnormal cracks level formation and opening by comparing them with existing methods is estimated.

scholarly journals Strength criterion for a plane stress reinforced concrete element under a special action

Vestnik MGSU ◽  
2020 ◽  
pp. 1513-1522
Author(s):  
Natalia V. Fedorova ◽  
Vu Ngoc Tuyen ◽  
Igor A. Yakovenko
Keyword(s):  
Reinforced Concrete ◽  
Progressive Collapse ◽  
Concrete Strength ◽  
Limit State ◽  
Strength Criterion ◽  
Structural Systems ◽  
Variable Loading ◽  
Concrete Element ◽  
Theory Of Plasticity ◽  
Concrete Elements

Introduction. Problem solving focused on the protection of buildings and structures from progressive collapse and minimization of resources, needed for this purpose, is becoming increasingly important. In many countries, including Russia, this type of protection is incorporated into national regulatory documents, and, therefore, any research, aimed at developing effective ways to protect structural systems from progressive collapse under special actions, is particularly relevant. In this regard, the present article aims to formulate effective strength criteria for such anisotropic materials as reinforced concrete to analyze plane stressed reinforced concrete structures exposed to sudden structural transformations caused by the removal of one of bearing elements. Materials and methods. To solve this problem, a variant of the generalized theory of plasticity of concrete and reinforced concrete, developed by G.A. Geniev, is proposed for application to the case of variable loading of a plane stressed reinforced concrete element. The acceptability of generalization of the strength criterion, pursuant to the theory of plasticity of concrete and reinforced concrete under static loading, and the applicability of this criterion to variable static-dynamic loading of reinforced concrete are used as the main hypothesis. An algorithm of an approximate method is presented as a solution to this problem; it allows to analyze the considered stress-strain state of plane stressed reinforced concrete elements. Results. The numerical analysis of the obtained solution, compared with the results of the experimental studies, was used to evaluate the designed strength criterion for reinforced concrete elements located in the area where the column is connected to the girder of a monolithic reinforced concrete frame in case of a sudden restructuring of a structural system. It is found out that the qualitative nature of the destruction pattern of the area under research, obtained in experiments, corresponds to the destruction pattern, identified by virtue of the analysis performed using the proposed criterion. Conclusions. The variant of the reinforced concrete strength criterion designated for the variable loading of a plane stressed reinforced concrete element and an algorithm for its implementation, based on the theory of plasticity of concrete and reinforced concrete developed by G.A. Geniev, is applicable to the analysis of a special limit state of reinforced concrete elements of structural systems of frames of buildings and structures.

scholarly journals Strength and deformability of reinforced concrete elements under oblique eccentric short-term dynamic compression, tension and bending

2020 ◽  
Vol 164 ◽  
pp. 14008
Author(s):  
Dmitriy Sarkisov ◽  
Nikolay Gorlenko ◽  
Gleb Gorynin ◽  
Yuri Sarkisov ◽  
Gafurzhan Izmailov ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Crack Resistance ◽  
Dynamic Compression ◽  
Longitudinal Force ◽  
Research Data ◽  
Deformation Model ◽  
Relative Resistance ◽  
Short Term ◽  
Concrete Elements ◽  
Central Tension

The paper deals with research data of reinforced concrete rectangular and I-shaped cross-section elements, operating under oblique eccentric short-term dynamic compression, tension and bending. The method of reinforced concrete elements calculation using the theory of surfaces of relative resistance regarding strength and crack resistance is suggested. It is based on the deformation model with the use of real nonlinear diagrams of concrete and reinforcement. This method makes it possible to observe strength and crack resistance of reinforced concrete elements sections in the entire range of loadings from the central tension to axial compression. Experimental investigation of symmetrically reinforced concrete elements on oblique eccentric short-term dynamic compression, tension and oblique bending was carried out. Effect of longitudinal force level on strain distribution through the depth of section, bearing capacity, the failure scheme and other parameters are estimated.

scholarly journals Normal Sections Calculation of Bending Reinforced Concrete and Fiber Concrete Elements

2018 ◽  
Vol 7 (3.2) ◽  
pp. 176
Author(s):  
Dmytro Kochkarev ◽  
Tatyana Galinska ◽  
Oleksandr Tkachuk
Keyword(s):  
Reinforced Concrete ◽  
Rectangular Cross Section ◽  
Nonlinear Function ◽  
Fiber Reinforced Concrete ◽  
Deformation Model ◽  
Fiber Reinforced ◽  
Deformation Diagram ◽  
First Case ◽  
Fiber Concrete ◽  
Concrete Elements

The basic principles of the normal sections calculation of reinforced concrete and fiber reinforced concrete bending elements are considered. In the article the power and deformation methods of calculation of reinforced concrete and fiber concrete elements of rectangular cross-section are presented. The deformation model of the calculation of reinforced concrete and fiber concrete elements is presented in the framework of the method of calculation resistance of the section. This method makes possible from the common methodological positions to perform calculations of reinforced concrete and fiber concrete elements. Namely, to select reinforcement and to determine the carring capacity. The proposed deformation model for calculating fiber concrete elements is based on generally accepted preconditions. A hypothesis of plane cross sections is accepted as fair. The deformation diagram of compressed concrete is described by a nonlinear function with established parametric points. Distribution of stresses in stretched concrete is taken rectangular with corresponding coefficients which are taken depending on the type of deformation diagram. Determination of the carring capacity of fiber concrete elements occurs under extreme deformation criteria. Two cases of destruction of the investigated elements are considered. The first case is the destruction due to the achievement of limiting deformations in the concrete of the compressed zone with the simultaneous achievement of the fluidity limit in the working reinforcement. The second case is the destruction due to the achievement of limiting deformations in the concrete of the compressed zone without reaching the fluidity limit in the working reinforcement. Both cases of calculation are reduced to one functional dependence. This avoids the delimitation of different calculation cases. The main no dimensional modifier is the mechanical coefficient of reinforcement. According to the developed method, examples of calculations of reinforced concrete, fiber reinforced concrete elements and fiber concrete elements with longitudinal reinforcement are executed. The possibility of a spread variant design of reinforced concrete and fiber concrete elements is shown. 

scholarly journals Design Model Of Bending Reinforced Concrete Elements Under Action Of Transverse Forces Under Conditions Of Increased And High Temperatures

2020 ◽  
Vol 02 (10) ◽  
pp. 17-24
Author(s):  
Mahkamov Y.M. ◽  
Keyword(s):  
Reinforced Concrete ◽  
Crack Resistance ◽  
High Temperatures ◽  
Experimental Studies ◽  
Calculation Model ◽  
Design Model ◽  
Stress Strain ◽  
Concrete Elements

In this article, the calculation of the strength and crack resistance of bending elements operating under conditions of high and high temperatures and transverse forces are proposed to be carried out according to a calculation model developed based on an analysis of experimental studies that takes into account more correctly the physics of the stress-strain phenomenon of the element.

scholarly journals Sectional Analysis Procedure for Reinforced Concrete Members Subjected to Pure Torsion

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Jongkwon Choi ◽  
Seong-Cheol Lee
Keyword(s):  
Reinforced Concrete ◽  
Analysis Procedure ◽  
Reinforced Concrete Beams ◽  
Biaxial Stress ◽  
Pure Torsion ◽  
Concrete Element ◽  
Concrete Members ◽  
Stress States ◽  
Sectional Analysis ◽  
Concrete Elements

A sectional analysis procedure for reinforced concrete members subjected to pure torsion is presented in this paper. On the development of the analysis procedure, the reinforced concrete section is modeled with reinforced concrete elements subjected to biaxial stress states, on the basis of the thin-walled tube analogy. Each reinforced concrete element is analyzed with the modified compression field theory (MCFT) to take into account for compression softening and tension stiffening effects in cracked reinforced concrete. Considering analysis results of reinforced concrete elements, equilibrium, and compatibility on the section are checked. For verification of the developed analysis procedure, analytical predictions were compared with test results of 16 reinforced concrete beams subjected to a pure torsional load which are available in the literature. Comparison between predicted and experimentally obtained torque-twist responses showed that the proposed procedure is capable of capturing the ultimate torsional capacity as well as the angle of twist within a reasonable range.

Improving the Methodology for Calculating the Bearing Capacity of Eccentrically Compressed Reinforced Concrete Elements Based on the Use of the Refined Curvilinear Deformation Diagrams of Concrete and Reinforcement

2019 ◽  
Vol 974 ◽  
pp. 570-576
Author(s):  
Alexander I. Nikulin ◽  
Al-Khawaf Ali Fadhil Qasim
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Linear Equations ◽  
Resistance Force ◽  
Deformation Model ◽  
Concrete Element ◽  
Element Determination ◽  
Numerical Studies ◽  
Concrete Elements ◽  
Deformation Diagrams

The article proposes a new approach to improving the methodology for calculating the bearing capacity of the eccentrically compressed reinforced concrete elements for cases of their loading with large eccentricities. The basis of this technique is considered as a modified version of the deformation model for the reinforced concrete resistance force. The main feature of this model is the energy approach to transforming the reference diagrams of compression and concrete tension into the diagrams of non-uniform deformation, corresponding to the stress-strain state of the compressed and stretched zones of concrete in the cross section of the eccentrically compressed reinforced concrete structures. This way there is no falling branch in the concrete diagrams obtained by this method. A calculation diagram of the steel reinforcement deformation with a physical yield point was taken as a partial function, consisting of one linear and two non-linear equations. The proposed method also shows the possibility of taking into account the greatest curvature of an eccentrically compressed reinforced concrete element in the plane of its loading. The article presents all the necessary dependencies allowing the theoretical value of the carrying capacity of an eccentrically compressed reinforced concrete element determination. The results of the numerical studies performed using the design software developed by the authors for the personal computer are given.

Strength of Normal and Inclined Sections of Bent Reinforced Concrete Elements with Zone Reinforcement Made of Steel Fiber

2022 ◽  
Vol 906 ◽  
pp. 7-15
Author(s):  
Dmitry Utkin
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Loading ◽  
Calculation Method ◽  
Steel Fiber ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Dynamic Loads ◽  
Reinforced Concrete Structures ◽  
Short Term ◽  
Concrete Elements

On the basis of theoretical and experimental studies, the prerequisites and the method of calculation of bent and compressed-curved reinforced concrete structures with zone reinforcement made of steel fiber, working under static and short-term dynamic loads, are formulated. In the developed method for calculating the strength of normal and inclined sections, a nonlinear deformation model is implemented, which is based on the actual deformation diagrams of materials. The developed calculation method is brought to the program of calculation of reinforced concrete structures with zone reinforcement of steel fiber under short-term dynamic loading, taking into account the inelastic properties of materials. The numerical studies made it possible to determine the influence of various parameters of steel-fiber reinforcement on the strength of reinforced concrete elements. To confirm the main results of the developed calculation method, experimental studies of reinforced concrete beam structures reinforced with conventional reinforcement and a zone steel-fiber layer are planned and carried out. Experimental studies were carried out under static and short-term dynamic loads. As a result of the conducted experiments, data were obtained that characterize the process of destruction, deformation and cracking of steel-reinforced concrete elements under such types of loading. The dependences of changes in the energy intensity of reinforced concrete structures with zone reinforcement made of steel fiber in the compressed and stretched cross-section zones under dynamic loading are obtained. The effectiveness of the use of fiber reinforcement of normal and inclined sections of bent and compressed-curved elements to improve the strength and deformative.

scholarly journals STUDYING CRACK RESISTANCE OF REINFORCED-CONCRETE − FIBRE-GLASS COMPOSITE PRESSURE PIPES FOR MICROTUNNELING

2019 ◽  
Author(s):  
M. Shepelevich ◽  
A. Puzan
Keyword(s):  
Reinforced Concrete ◽  
Hydrostatic Pressure ◽  
Crack Resistance ◽  
Cross Sections ◽  
Pipe Wall ◽  
Crack Opening ◽  
Experimental Studies ◽  
Glass Composite ◽  
Fibre Glass ◽  
Pressure Pipes

The results are given for experimental studies of crack resistance of reinforced-concrete - fibre-glass composite pressure pipes when affected by three-way load and internal hydrostatic pressure. Pipes are designed for construction of pressure pipelines, using the trenchless laying (microtunneling) method. BelNIIS Institute Republican Unitary Enterprise (RUE) has developed the design solutions and engineering drawings of pipes in accordance with the order placed by Steklokompozit Industrial Company, Russia. Pipes are made as integrated ones, and they consist of an external thick-wall reinforced-concrete pipe (the cage) enveloping an insert pipe made of fibre-glass composite. Full-scale specimens of pipes with the inner diameter of 800 mm and the (effective) length of 3000 mm were used for studies. The total thickness of pipe wall was 138 mm, with the fibre-glass composite insert thickness 10 mm. Pipes were made in vertical position, with the vibroforming method used for this purpose. During the concrete mixture laying procedure, the fibre-glass composite insert pipe joined with the fibre-glass composite sleeve was used as a permanent formwork. The experimental studies were carried out in two steps: I pipes (2 specimens) were tested by the internal hydrostatic pressure II pipes (2 specimens), including a hydraulically-tested specimen, were tested by the three-way load (according to GOST 6482). During the tests, formation and opening of cracks in longitudinal cross-sections of pipe wall was registered. It was found that strength characteristics of integrated reinforced-concrete composite pipes provide their load-carrying capacity against both the internal hydraulic pressure and the external (three-way) load applied. Thus, when reference loads in terms of crack resistance were applied, there were no cracks in longitudinal cross-sections of pipes when reference loads in terms of strength were applied, the crack opening width never exceeded 0.05 mm. Also, both with the internal pressure and the three-way load applied, the crack opening widths in longitudinal cross-sections of a reinforced-concrete cage were significantly (1.52.5 times) less than the corresponding values resulting from pipe design calculations carried out in accordance with procedures being in force.Приведены результаты экспериментальных исследований трещиностойкости железобетонно-стеклокомпозитных напорных труб при действии трехлинейной нагрузки и внутреннего гидростатического давления. Трубы предназначены для строительства напорных трубопроводов методом бестраншейной прокладки (методом микротоннелирования). Конструктивные решения и рабочие чертежи труб разработаны РУП Институт БелНИИС по заказу ПО Стеклокомпозит (Россия). Трубы выполнены комплексными и состоят из внешней толстостенной железобетонной трубы (обоймы), охватывающей стеклокомпозитную трубу-вкладыш. Исследования произведены с использованием натурных образцов труб внутренним диаметром 800 мм и длиной ( полезной ) 3000 мм. Суммарная толщина стенки трубы составляла 138 мм при толщине стеклокомпозитного вкладыша 10 мм. Трубы изготовлены в вертикальном положении методом виброформования. При укладке бетонной смеси стеклокомпозитная труба-вкладыш, состыкованная со стеклокомпозитной муфтой, использовалась как несъемная опалубка. Экспериментальные исследования выполнены в два этапа: I трубы (2 образца) испытаны внутренним гидравлическим давлением II трубы (2 образца), в т. ч. образец, прошедший гидравлические испытания, испытаны трехлинейной нагрузкой (по ГОСТ 6482). В процессе испытаний фиксировали образование и раскрытие трещин в продольных сечениях стенки трубы. Установлено, что прочностные характеристики комплексных железобетонно-композитных напорных труб обеспечивают их несущую способность как при внутреннем гидравлическом давлении, так и под действием внешней (трехлинейной) нагрузки. Так, при контрольных нагрузках по трещиностойкости трещины в продольных сечениях труб отсутствовали, а при контрольных нагрузках по прочности ширина раскрытия трещин не превышала 0,05 мм. При этом как при действии внутреннего давления, так и при трехлинейной нагрузке ширина раскрытия трещин в продольных сечениях железобетонной обоймы существенно (в 1,52,5 раза) меньше, чем соответствующие значения, полученные в результате расчета труб по действующим методикам.

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