scholarly journals Parametric Study of Concrete Members with GFRP Reinforcement Subjected to Bending and Axial Force

2021 ◽  
Vol 1203 (2) ◽  
pp. 022130
Author(s):  
Žaneta Šenšelová ◽  
Viktor Borzovič ◽  
Jaroslav Baran
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Axial Force ◽  
Modulus Of Elasticity ◽  
Parametric Study ◽  
Steel Reinforcement ◽  
Concrete Element ◽  
Electrical Insulator ◽  
Concrete Elements ◽  
Gfrp Reinforcement

Abstract The paper deals with the possible replacement of steel reinforcement by GFRP reinforcement for concrete elements subjected to bending moment and compressive axial force. For the last 15 years, Fibre Reinforced Polymer (FRP) bars became more popular and commercially available as reinforcement for concrete elements. Composite FRP materials are still new in construction and many engineers are not familiar with their properties and behaviour. FRP has certain advantages over steel reinforcement. It is a durable material that is not subject to corrosion, does not conduct heat, is an electrical insulator and conducts electrical current, and is non-magnetic. In contrast, FRP also has certain deficiencies such as sensitivity to higher temperatures, alkaline environments, and reduction of mechanical properties at high levels of long-term stress. In the case of FRP reinforcements, the plastic branch is missing in the σ-ε diagrams, what leads to a sudden failure of the reinforced concrete element, either by tensile rupture of the reinforcement or by crushing the concrete. The most used FRP reinforcement is made of glass fibres - GFRP reinforcement. The paper deals with the possible replacement of steel reinforcement by GFRP reinforcement for slab and beam elements. The text describes a parametric study for different reinforcement ratio with GFRP reinforcement and steel reinforcement. The study is performed for a cross-section of 500x500 mm for a column element and a cross-section of 1000x250 mm for a slab element. The effect of longitudinal GFRP reinforcement in elements under compression was investigated. The study contains a comparison of interaction P-M diagrams of concrete elements with steel and GFRP reinforcement. For design of GFRP reinforced concrete elements, it is necessary to consider different material characteristics such as tensile strength and modulus of elasticity. The contribution of the GFRP reinforcement in compression was neglected due to the anisotropic nature of the GFRP reinforcement and the low modulus of elasticity. The main reference basis for the elaboration of a parametric study is the fib Bulletin No. 40.

scholarly journals Comparison of the effect of GFRP and steel reinforcement in concrete members subjected to compressive stress

2021 ◽  
Vol 1209 (1) ◽  
pp. 012061
Author(s):  
Ž Šenšelová ◽  
V Borzovič
Keyword(s):  
Tensile Strength ◽  
Modulus Of Elasticity ◽  
Elevated Temperatures ◽  
Steel Reinforcement ◽  
Concrete Element ◽  
Electrical Insulator ◽  
Low Weight ◽  
The Impact ◽  
Concrete Elements ◽  
Gfrp Reinforcement

Abstract Composite materials became more popular and commercially available as reinforcement for concrete elements. Fibre Reinforced Polymer (FRP) bar is an excellent thermal and electrical insulator with high tensile strength and low weight. These assumptions make them a possible substitution for steel reinforcement. Moreover, GFRP is not responsible to corrosion for that are suitable for structures with high humidity and unfavorable environment. GFRP is easier to handle due to its low weight. Also, it has electromagnetic neutrality. But it has some disadvantages. It has a low modulus of elasticity and sensitivity to elevated temperatures. Another drawback and uncertainty with designing is the impact of an alkaline environment, which decreases the long-term strength of GFRP bars. This paper describes a pre-experiment study of concrete elements resistance. The analysis is performed for a cross-section of 200x150 mm for a short concrete column with steel and GFRP reinforcement. The study compares P-M diagrams for steel reinforcement and GFRP reinforcement with different reinforcement ratios. Other characteristics such as tensile strength and modulus of elasticity must be considered to design the GFRP reinforced concrete element. The study also considers the contribution of GFRP reinforcement in compression. The analysis has shown, the shape of interaction diagrams of steel and GFRP reinforcement are significantly different.

scholarly journals The technology of experimental researches of the strength of bent reinforced concrete elements in the zone of action of transverse forces

2021 ◽  
Author(s):  
I.N. Starishko
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Cross Section ◽  
Steel Reinforcement ◽  
Inclined Crack ◽  
Shear Span ◽  
Depth Analysis ◽  
The Cross ◽  
Experimental Researches ◽  
Concrete Elements

Extensive experimental researches of the author of the article showed that in T-profile beams, despite the fact that with an increase in the length of the shear span, the bearing capacity along inclined sections significantly decreases, the effect of overhangs of compressed flanges on the bearing capacity of these beams, on the contrary, increases, and when, with an increase in the length of the shear span, the beam becomes equal in strength in normal and inclined sections, the effect of overhangs, as a rule, becomes the same in both the strength of normal and the strength of inclined sections, which is not taken into account in the regulatory documents of Russia, the USA and a number of other countries. At the same time, experiments have shown that the smaller the rib width in the cross section of bent reinforced concrete T-profile beams (standard beams of bridge structures on the territory of Russia), the greater the effect of the overhangs of compressed flanges on their bearing capacity along inclined sections. The values of the influences on the bearing capacity of bent reinforced concrete elements of such factors as: the forces of engagement of the rough surface of the banks when they are displaced in an inclined crack from the action of the load; the nagel effect in the longitudinal steel reinforcement at the intersection of it with an inclined crack; prestressing in longitudinal steel reinforcement, depending on the amount of transverse steel reinforcement and the width of the cross-section of the elements, etc. The technology for conducting experimental researches will have a positive effect for the development of a reliable theory for calculating bent reinforced concrete elements along inclined sections only when it includes the whole complex of a variety of the influence of the main factors on the operation of the researched elements with its in-depth analysis.

scholarly journals An experimental study on variability of deformation characteristics of concrete in compression

Vestnik MGSU ◽  
2020 ◽  
pp. 1390-1398
Author(s):  
Mixail G. Plyusnin ◽  
Sergey V. Tsybakin
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Cross Section ◽  
Strength Analysis ◽  
Deformation Model ◽  
Deformation Characteristics ◽  
Concrete Element ◽  
Linear Deformation ◽  
Concrete Elements

Introduction. An experimental study on variability of deformation characteristics of concrete and an assessment of its influence on the bearing capacity of eccentrically compressed reinforced concrete elements were performed. In pursuance of effective regulatory documents, a non-linear deformation model was applied to perform the strength analysis of standard cross sections of reinforced concrete structures. The application of this method in probabilistic design is also of interest. Analytical functions approximating the true σ–ε diagram, made for concrete, use strength and deformation characteristics of concrete as parameters. However, variability of deformation characteristics of concrete has not been sufficiently studied, although it may have significant influence on results of analyses. Materials and methods. Complete σ–ε diagrams were made for uniaxially compressed concrete to solve this problem. These diagrams were applied to numerically assess the influence of variability of deformation characteristics of concrete on the bearing capacity of an eccentrically compressed reinforced concrete element in terms of its standard cross section. A non-linear deformation model was used to identify the bearing capacity. Results. The experiment has proven substantial variation of diagram shapes within the same strength class. The influence of the εb0 value of ultimate deformations of concrete on the bearing capacity is demonstrated for a standard cross section as a result of the strength analysis of an eccentrically compressed reinforced concrete element. The strength analysis was performed by applying experimental σ–ε diagrams made for uniaxially compressed concrete. Conclusions. The analysis of the findings has shown that the value of ultimate deformations of concrete exposed to uniaxial compression affects the bearing capacity of eccentrically compressed reinforced concrete elements. The degree of influence depends on concrete strength, reinforcement percentage and the eccentricity of a longitudinal force.

SETTING A DIAGRAM APPROACH TO CALCULATING VIBRATED, CENTRIFUGED AND VIBROCENTRIFUGED REINFORCED CONCRETE COLUMNS WITH A VARIATROPIC STRUCTURE

2020 ◽  
pp. 22-34
Author(s):  
Л. Р. Маилян ◽  
С. А. Стельмах ◽  
Е. М. Щербань ◽  
М. П. Нажуев
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Cross Section ◽  
Concrete Columns ◽  
Reinforced Concrete Columns ◽  
The Cross ◽  
Concrete Elements ◽  
Diagram Approach

Состояние проблемы. Железобетонные элементы изготавливаются, как правило, по трем основным технологиям - вибрированием, центрифугированием и виброцентрифугированием. Однако все основные расчетные зависимости для определения их несущей способности выведены, исходя из основного постулата - постоянства и равенства характеристик бетона по сечению, что реализуется лишь в вибрированных колоннах. Результаты. В рамках диаграммного подхода предложены итерационный, приближенный и упрощенный способы расчета несущей способности железобетонных вибрированных, центрифугированных и виброцентрифугированных колонн. Выводы. Расчет по диаграммному подходу показал существенно более подходящую сходимость с опытными данными, чем расчет по методике норм, а также дал лучшие результаты при использовании дифференциальных характеристик бетона, чем при использовании интегральных и, тем более, нормативных характеристик бетона. Statement of the problem. Reinforced concrete elements are typically manufactured according to three basic technologies - vibration, centrifugation and vibrocentrifugation. However, all the basic calculated dependencies for determining their bearing capacity were derived using the main postulate, i.e., the constancy and equality of the characteristics of concrete over the cross section, which is implemented only in vibrated columns. Results. Within the framework of the diagrammatic approach, iterative, approximate and simplified methods of calculating the bearing capacity of reinforced concrete vibrated, centrifuged and vibrocentrifuged columns are proposed. Conclusions. The calculation according to the diagrammatic approach showed a significantly better convergence with the experimental data than that using the method of norms, and also performs better when using differential characteristics of concrete than when employing integral and particularly standard characteristics of concrete.

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 Two-layer reinforced concrete panels with uniformly compressed sections

2020 ◽  
Vol 315 ◽  
pp. 07004
Author(s):  
Dmitry Mailyan ◽  
Alik Blyagoz ◽  
Konstantin Kretinin
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Panels ◽  
The Creation ◽  
Concrete Elements

The paper contains the issues related to the creation of a non-uniform prestress cross-section of reinforced concrete elements compressed during operation of working with a one-way eccentricity of the resultant longitudinal forces.

scholarly journals Dependency of Elastic Modulus and Stress Redistribution Coefficients on a Layout of Steel Reinforcement in Steel-Concrete Cross Section

2011 ◽  
Vol 11 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Karel Vojtasík ◽  
Eva Hrubešová ◽  
Marek Mohyla ◽  
Jana Staňková
Keyword(s):  
Elastic Modulus ◽  
Cross Section ◽  
Parametric Study ◽  
Steel Reinforcement ◽  
The State ◽  
Reinforcement Ratio ◽  
Stress Redistribution ◽  
Elastic Module ◽  
Design Value ◽  
State Stress

Dependency of Elastic Modulus and Stress Redistribution Coefficients on a Layout of Steel Reinforcement in Steel-Concrete Cross Section The paper presents the outputs of a computational parametric study investigating the influence of both reinforcement ratio and scheme of a cross-section reinforcement on a design value of the elastic module for the homogenized cross-section and the values of the stress redistribution coefficients. The design value of the elastic module represents the steel-concrete cross section in the calculations. The stress redistribution coefficients converts the state stress in the homogenized cross-section for the state stress in steel and concrete individually. The design value of the homogenized cross-section elastic module and the stress redistribution coefficients are determined from the theory of the cooperating rings and computed by program HOMO. The result of a study is a set of the stress redistribution coefficients and a dependency of stress redistribution coefficients on the reinforcement ratio of a steel-concrete section.

scholarly journals Parametric Study on Moment Redistribution of Fiber Reinforced Concrete Continuous Beams with Basalt FRP Bars

2020 ◽  
Author(s):  
Abdelrahman Hamdi Abushanab ◽  
Wael I Alnahhal
Keyword(s):  
Reinforced Concrete ◽  
Parametric Study ◽  
Steel Reinforcement ◽  
Reinforcement Ratio ◽  
Fiber Reinforced Concrete ◽  
Elastic Behaviour ◽  
Fiber Reinforced ◽  
Moment Redistribution ◽  
Continuous Beams ◽  
Frp Bars

The state of Qatar is suffering from its harsh environment and coastal conditions, which stand for most of the year. As a result, steel-reinforced concrete structures are subjected to rapid corrosion and deterioration. Therefore, there is a necessity to replace the conventional steel reinforcement by fiber-reinforced polymers (FRP) bars. Apart from FRP bars corrosion resistance, their strength to weight ratio is higher than steel reinforcement, which made the FRP, bars a viable alternative to steel reinforcement. Continuous concrete beams are commonly used elements in structures such as parking garages and overpasses. In such structures, forces could be distributed between the critical sections after cracking. This phenomenon is called moment redistribution. It reduces the congested rebars in connections and enhances the ductility of the members. However, the linear-elastic behaviour of FRP materials makes the ability of continuous beams to redistribute loads and moments questionable. This study aims to investigate the capability of moment redistribution of basalt fiber reinforced concrete (BFRC) continuous beams reinforced with basalt FRP (BFRP) bars. Eleven reinforced concrete (RC) continuous beams of 200 x 300 x 4000 mm were tested up to failure under fivepoint loading. The main investigated parameters were the reinforcement ratio (0.6rb, 1.0rb, 1.8rb and 2.8rb; where rb is the balanced reinforcement ratio), stirrups spacing (80 and 120 mm) and volume fractions of Basalt-macro fibers (BMF) (0.75 and 1.5%). A parametric study was then conducted using a validated finite element (FE) model to extend the investigated parameters that may affect the moment redistribution of RC continuous beams. It was concluded that moment redistribution occurs in beams that have at least a ratio of bottom to top reinforcement of 0.3.

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.

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