scholarly journals MODELING OF STRESS-DEFORMED STATE OF BENDED REINFORCED CONCRETE ELEMENTS IN ZONES OF CLEAN AND TRANSVERSE BEND

2021 ◽  
Vol 11 (1) ◽  
pp. 26-33
Author(s):  
Anatoly A. PROKOPOVICH ◽  
Yana A. BUZOVSKAYA
Keyword(s):  
Reinforced Concrete ◽  
Experimental Studies ◽  
Element Model ◽  
Successive Approximations ◽  
Method Of Successive Approximations ◽  
Concrete Element ◽  
Nite Element ◽  
Deformed State ◽  
System Of Cracks ◽  
Concrete Elements

The article deals with the analysis of the stress-strain state (SSS) of a bent reinforced concrete element in zones of pure and transverse bending. It is assumed that a bent element in the process of loading (after the formation of normal and oblique cracks) is divided into blocks, united by uncracked concrete and reinforcement that has adhesion to concrete. SSS was formed using the results of experimental studies of special prototypes in the PC “Lira-SAPR”. A fi nite element model of a prototype has been developed in the form of a reinforced concrete rectangular beam loaded with two identical concentrated forces in the span. By the method of successive approximations, the process of formation and formation of a system of cracks is realized, with which the beam is divided into blocks during loading. The results of calculating the fi nite element model and their comparison with experimental data are presented.

scholarly journals INTEGRAL PARAMETERS OF CONCRETE DIAGRAMS FOR CALCULATIONS OF STRENGTH OF REINFORCED CONCRETE ELEMENTS USING THE DEFORMATION MODEL

2020 ◽  
Vol 16 (1) ◽  
pp. 25-37
Author(s):  
Vladimir Eryshev ◽  
Nickolay Karpenko ◽  
Artur Zhemchuyev
Keyword(s):  
Reinforced Concrete ◽  
Successive Approximations ◽  
Method Of Successive Approximations ◽  
Deformation Model ◽  
Concrete Element ◽  
Normative Documents ◽  
Functional Relationships ◽  
Regulatory Documents ◽  
Base Points ◽  
Analytical Expressions

In accordance with the requirements of regulatory documents, restrictions are introduced on stress levels at the end of the falling branch of the diagrams at the maximum normalized strain values. We have developed mathematical models that establish a uniform sequence for calculating the unambiguous values of deformations at the base points of concrete diagrams, taking into account the accepted functional relationships and the rules for their use according to the tables of normative documents. It was shown that for equal values of deformations and stresses at base points, analytical expressions of diagram recommended by regulatory documents, even if it differs in structure, give identical outlines, diagram branches coincide. The correlation between the calculation models by Russian and foreign regulatory documents was established by comparing the values of the integral parameters of the diagrams and the ultimate forces obtained by calculating the reinforced concrete element according to the deformation model. As integral parameters of concrete deformation diagrams, it was recommended to use areas bounded by diagram branches and diagram completeness coefficients. Analytical modeling of integral parameters allowed us to exclude the procedure for numerically summing stresses along elementary strips in a section and solving nonlinear equations by the method of successive approximations when calculating the strength of an element.

The development of A Simulation Tool for Numerical Modelling of High Flexure and High Shear Reinforced Concrete Elements

Teknik ◽  
2021 ◽  
Vol 42 (2) ◽  
pp. 106-116
Author(s):  
Nuroji Nuroji ◽  
Muhammad Rony Asshidiqie ◽  
Sukamta Sukamta ◽  
Ay Lie Han
Keyword(s):  
Reinforced Concrete ◽  
Element Model ◽  
Sensitivity Analyses ◽  
Shear Stresses ◽  
Concrete Element ◽  
Independent Variables ◽  
Accuracy And Precision ◽  
Set Up ◽  
High Degree ◽  
Concrete Elements

The weakness of full-scale testing of reinforced concrete elements in a laboratory is the long period, both to prepare and test specimens and the high-cost, resulting in a limited number of specimens. The heavy specimen creates another difficulty during set-up. Data accuracy depends on apparatus precision, laboratory conditions, and the technicians' expertise in experimenting. A finite element model was constructed to simulate a reinforced concrete element subject to high flexure and shear stresses induced by vertical and horizontal forces to overcome these constraints. The model can further be utilized to evaluate the effects of independent variables on the behavior of the member. The model was validated both numerically and experimentally to ensure accuracy and precision. The numerical validation was conducted through a sensitivity analyses process on the finesses of meshing and loading incrementation. At the same time, the load-deformation data and the crack propagation of identical laboratory-tested elements were utilized for validation of the experimental data. It was proven that the developed model predicts the behavior of the beam to a high degree of correctness. The model can further be used as a tool for analyses in the field.

Evaluation of the Compressed Reinforced Concrete Elements Dynamic Strength, Taking into Account the Temperature Influence on the Strength and Deformability of Reinforcement Steel and Concrete

2018 ◽  
Vol 931 ◽  
pp. 334-339
Author(s):  
Levon A. Avetisyan ◽  
Mikhail V. Danilov
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Stiffness ◽  
Experimental Studies ◽  
Dynamic Strength ◽  
Concrete Element ◽  
Internal Forces ◽  
The Moment ◽  
Increasing Temperature ◽  
In Fire ◽  
Concrete Elements

In the article the results of the eccentrically compressed reinforced concrete element calculation operating under the dynamic loading in fire conditions are shown. The calculation of the compressed reinforced concrete element was carried out, taking into account the conducted experimental studies. The calculation showed that, depending on the temperature effects, the curvature of the reinforced concrete element in stages I and II decreases while the class concrete, which varies from 28.9% to 55%, is increasing. When the temperature reaches 2500, the cracking moment and the moment of internal forces at the end of the stage II are reduced to 22% with respect to these forces at normal conditions. With increasing temperature, the dynamic stiffness of the element in the stage I is reduced by 29.3%.

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.

Using of Plastic Hinges in the Calculation of Buildings against Progressive Collapse under Fire Exposure

2018 ◽  
Vol 878 ◽  
pp. 115-120
Author(s):  
Levon Avetisyan
Keyword(s):  
Reinforced Concrete ◽  
Progressive Collapse ◽  
Experimental Studies ◽  
Fire Exposure ◽  
Reinforced Concrete Frame ◽  
Dynamic Calculation ◽  
Plastic Hinges ◽  
Concrete Frame ◽  
In Fire ◽  
Concrete Elements

This article presents a study of the strength of a 25-storey reinforced concrete frame against progressive collapse in fire conditions. Taking into account the angles of disclosure of plastic hinges as norming for the strength of reinforced concrete elements, a computer technology program has been developed and included in PR Wolfram Mathematica 10 for the dynamic calculation of compressed reinforced concrete elements under fire exposure on the basis of the conducted experimental studies. Dynamic calculation of the strength of eccentrically compressed reinforced concrete columns was carried out, with operation in normal conditions and under high temperatures. The diagram «moment-curvature» and the graph of the change of the static and dynamic strength of the column depending on the temperature were developed. Nonlinear dynamic analysis of a 25-storey reinforced concrete frame was conducted, taking into account the changes of the dynamic characteristics of reinforced concrete elements in fire and, the estimation of resistance of the frame was given.

scholarly journals Shear Behaviour of RC Beams Strengthened by Various Ultrahigh Performance Fibre-Reinforced Concrete Systems

2020 ◽  
Vol 2020 ◽  
pp. 1-18 ◽  
Author(s):  
Walid Mansour ◽  
Bassam A. Tayeh
Keyword(s):  
Reinforced Concrete ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Element Model ◽  
Shear Behaviour ◽  
Fibre Reinforced Concrete ◽  
Rc Beams ◽  
Shear Span ◽  
Depth Ratio ◽  
Normal Strength

This study presents a numerical investigation on the shear behaviour of shear-strengthened reinforced concrete (RC) beams by using various ultrahigh performance fibre-reinforced concrete (UHPFRC) systems. The proposed 3D finite element model (FEM) was verified by comparing its results with those of experimental studies in the literature. The validated numerical model is used to analyse the crucial parameters, which are mainly related to the design of RC beams and shear-strengthened UHPFRC layers, such as the effect of shear span-to-depth ratio on the shear behaviour of the strengthened or nonstrengthened RC beams and the effect of geometry and length of UHPFRC layers. Moreover, the effect of the UHPFRC layers’ reinforcement ratio and strengthening of one longitudinal vertical face on the mechanical performance of RC beams strengthened in shear with UHPFRC layers is investigated. Results of the analysed beams show that the shear span-to-depth ratio significantly affects the shear behaviour of not only the normal-strength RC beams but also the RC beams strengthened with UHPFRC layers. However, the effect of shear span-to-depth ratio has not been considered in existing design code equations. Consequently, this study suggests two formulas to estimate the shear strength of normal-strength RC beams and UHPFRC-strengthened RC beams considering the effect of the shear span-to-depth ratio.

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.

scholarly journals Strength resistance of reinforced concrete elements of high-rise buildings under dynamic loads

2018 ◽  
Vol 33 ◽  
pp. 02049 ◽  
Author(s):  
Mikhail Berlinov
Keyword(s):  
Reinforced Concrete ◽  
Strain State ◽  
Load Capacity ◽  
Phenomenological Theory ◽  
Dynamic Loads ◽  
Successive Approximations ◽  
Step Method ◽  
High Rise ◽  
The Finite Difference Method ◽  
Concrete Elements

A new method for calculating reinforced concrete constructions of high-rise buildings under dynamic loads from wind, seismic, transport and equipment based on the initial assumptions of the modern phenomenological theory of a nonlinearly deformable elastic-creeping body is proposed. In the article examined the influence of reinforcement on the work of concrete in the conditions of triaxial stress-strain state, based on the compatibility of the deformation of concrete and reinforcement. Mathematical phenomenological equations have been obtained that make it possible to calculate the reinforced concrete elements working without and with cracks. A method for linearizing of these equations based on integral estimates is proposed, which provides the fixation of the vibro-creep processes in the considered period of time. Application of such a technique using the finite-difference method, step method and successive approximations will allow to find a numerical solution of the problem. Such an approach in the design of reinforced concrete constructions will allow not only more fully to take into account the real conditions of their work, revealing additional reserves of load capacity, but also to open additional opportunities for analysis and forecasting their functioning at various stages of operation.

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