scholarly journals Modelling the Deformation of Steel-bars in Reinforced Concrete Beams Submerged in Lagoon

2021 ◽  
Vol 18 (3) ◽  
pp. 219-228
Author(s):  
J.O. Akinyele ◽  
U.T. Igba ◽  
F.M. Alayaki ◽  
S.I. Kuye
Keyword(s):  
Reinforced Concrete ◽  
Fresh Water ◽  
Concrete Beams ◽  
Mechanical Tests ◽  
Reinforced Concrete Beams ◽  
Finite Element Program ◽  
Element Program ◽  
Bond Strengths ◽  
One Year ◽  
Concrete Elements

Corrosion of steel and spalling of concrete in reinforced concrete elements have become a common occurrence in structures that are built around marine environment. This research investigated the effect of chloride on the steel in reinforced concrete beams. Mechanical tests such as; compressive, flexural and bond strengths were done on replicate concrete elements which were cast and buried for a maximum of one year in the Lagos lagoon. Twenty-four number of 150 mm x 150 mm x 600 mm sized reinforced concrete beams were cast for the flexural strength test, while forty-eight concrete cubes were cast for both compressive and bond strength tests, samples were cured in both lagoon and fresh water (The fresh water is for the control). A finite element program, ANSYS was used to model the deformation (deflection) of the steel reinforcement in the beams. Results showed a general reduction in compressive, flexural and bond strengths for the concrete samples buried in the lagoon, while those buried in freshwater showed an increase in strength as the concrete ages. The modelled results of the reinforcement showed a one-year deformation rate (r = 0.0181) in the steel of concrete buried in lagoon water. This value was used to estimate the future and past deformation values of these reinforcements due to chloride attack.

Strengthening of Concrete Beams Having Shear Zone Openings Using Orthotropic CFRP Modeling

2011 ◽  
Vol 147 ◽  
pp. 19-23
Author(s):  
Ashraf Mohamed Mahmoud
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Element Model ◽  
Reinforced Concrete Beams ◽  
Concrete Element ◽  
Finite Element Program ◽  
Proposed Model ◽  
Element Program ◽  
Orthotropic Properties

A finite element reinforced concrete model has been analyzed by the author with ANSYS 9 finite element program for both unstrengthened and CFRP-strengthened beams using concrete element model 25x25x25mm and discrete and smeared steel distribution with openings exist. The CFRP has been modeled using Solid46 element, which has orthotropic properties. The deflection results have been compared with an experimental and other finite element model which are performed by Mohamed [4], in which using 100x42.5x42.5 mm concrete element, smeared steel distribution with the same opening sizes, and modeling CFRP with ANSYS 5 finite element program using Link10 element which has a uniaxial properties. These results show that the author's model is much better than the Mohamed's [4] model comparing with the experimental one. A parametric study has been done on the proposed model for obtaining the maximum strains values for concrete and steel at failure loads, for different opening sizes and comparing them with the experimental one. This study show a good agreement between the proposed and experimental model results for strains values which indicate the efficiency of the proposed model for analyzing the unstrengthend and strengthened reinforced concrete beams.

scholarly journals Application of artificial neural networks to predict the deflections of reinforced concrete beams

2016 ◽  
Vol 38 (2) ◽  
pp. 37-46 ◽  
Author(s):  
Mateusz Kaczmarek ◽  
Agnieszka Szymańska
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Artificial Neural Network ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
The Neural Network ◽  
Eurocode 2 ◽  
Artificial Neural ◽  
Concrete Elements

Abstract Nonlinear structural mechanics should be taken into account in the practical design of reinforced concrete structures. Cracking is one of the major sources of nonlinearity. Description of deflection of reinforced concrete elements is a computational problem, mainly because of the difficulties in modelling the nonlinear stress-strain relationship of concrete and steel. In design practise, in accordance with technical rules (e.g., Eurocode 2), a simplified approach for reinforced concrete is used, but the results of simplified calculations differ from the results of experimental studies. Artificial neural network is a versatile modelling tool capable of making predictions of values that are difficult to obtain in numerical analysis. This paper describes the creation and operation of a neural network for making predictions of deflections of reinforced concrete beams at different load levels. In order to obtain a database of results, that is necessary for training and testing the neural network, a research on measurement of deflections in reinforced concrete beams was conducted by the authors in the Certified Research Laboratory of the Building Engineering Institute at Wrocław University of Science and Technology. The use of artificial neural networks is an innovation and an alternative to traditional methods of solving the problem of calculating the deflections of reinforced concrete elements. The results show the effectiveness of using artificial neural network for predicting the deflection of reinforced concrete beams, compared with the results of calculations conducted in accordance with Eurocode 2. The neural network model presented in this paper can acquire new data and be used for further analysis, with availability of more research results.

scholarly journals NONLINEAR FINITE ELEMENT ANALYSIS OF DAMAGED AND STRENGTHENED REINFORCED CONCRETE BEAMS

2014 ◽  
Vol 20 (2) ◽  
pp. 201-210 ◽  
Author(s):  
Muharrem Aktas ◽  
Yusuf Sumer
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Structural Response ◽  
Experimental Tests ◽  
Reinforced Concrete Beams ◽  
Bending Test ◽  
Element Analysis ◽  
Finite Element Program ◽  
Moment Capacity

Bending test of seven reinforced concrete beams are modeled in finite element program to validate the modeling strategies by comparing the structural response of the beams. Three beams in the set are pre-damaged and strengthened with fiber reinforced composites before the bending tests. Cracks are implemented into the model by inserting geometrical discontinuities to represent the pre-damaged beams. Parametric variables such as crack width, length and interval are chosen to simulate different pre-damage levels. Once the proposed modeling strategies are validated by real experimental tests then 196 finite element models are created to study the effects of pre-damage levels on the moment capacity of reinforced concrete beams repaired with CFRP. Results indicate that inclusion of pre-damage levels by means of cracks into the cross sections have significant effect on beams moment capacity.

scholarly journals Experimental Validation of Finite Element Models for Reinforced Concrete Beams with Discontinuities That Form Dowel-Type Joints

Vibration ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 537-550
Author(s):  
Marios Filippoupolitis ◽  
Carl Hopkins
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Modal Assurance Criterion ◽  
Fem Model ◽  
Beam Elements ◽  
Concrete Elements

Earthquakes have the highest rate of mortality among the natural disasters and regularly lead to collapsed structures with people trapped inside them. When a reinforced concrete building collapses due to an earthquake, many of the concrete elements (i.e., beams and columns) are damaged and there are large sections where the concrete is missing and the steel reinforcement is exposed (i.e., concrete discontinuities). The prediction of vibration transmission in collapsed and severely damaged reinforced-concrete buildings could help decisions when trying to detect trapped survivors; hence there is need for experimentally validated finite element models of damaged concrete elements. This paper investigates the dynamic behaviour of damaged reinforced concrete beams using Experimental Modal Analysis (EMA) and Finite Element Methods (FEM). FEM models are assessed using two beams with one or more concrete discontinuities that form dowel-type joints. These models used either beam or spring elements for the exposed steel bars and were experimentally validated against EMA in terms of eigenfrequencies and mode shapes. Improved agreement was achieved when using springs instead of beam elements in the FEM model. The comparison of mode shapes used the Partial Modal Vector Ratio (PMVR) as a supplement to the Modal Assurance Criterion (MAC) to confirm that spring elements provide a more accurate representation of the response on all concrete parts of the beams.

scholarly journals Simulation of the Stress-Strain State of Eccentrically Compressed and Tensioned Reinforced Concrete Beams

2020 ◽  
Vol 2 (1) ◽  
pp. 207-214
Author(s):  
Vasyl Karpiuk ◽  
Yuliia Somina ◽  
Oksana Maistrenko ◽  
Fedir Karpiuk
Keyword(s):  
Reinforced Concrete ◽  
Cross Sections ◽  
Strain State ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Improved Method ◽  
Stress Strain ◽  
Stress Strain State ◽  
Strain Behaviour ◽  
Concrete Elements

AbstractThe paper deals with the working peculiarities of the support zones of reinforced concrete elements subject to bending with due account of the eccentric compression and tension. The authors performed simulation of the stress-strain behaviour of the indicated structures with the aid of “Lira” software which results are shown in the graphical and tabulated form. The performed simulation allowed of tracing the work of the studied sample beams till collapse. Such approach made it possible to single out and generalize the main collapse patterns of the inclined cross-sections of the reinforced concrete elements subject to bending on which basis the authors developed the improved method to calculate their strength (Karpiuk et al., 2019).

scholarly journals RESEARCH OF THE INFLUENCE OF LONGITUDINAL COMPRESSION ON THE STRENGTH OF THE WALL OF TWO-TURNED REINFORCED CONCRETE ELEMENTS WITH A CHARACTERISTIC EPURA BENDING MOMENTS IN THE AREA OF ACTION OF LATERAL FORCES

2021 ◽  
Vol 3 (72) ◽  
pp. 34-37
Author(s):  
A. Abdullaev .
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Experimental Studies ◽  
Compressive Force ◽  
Reinforced Concrete Beams ◽  
Bending Moments ◽  
Shear Forces ◽  
Longitudinal Compression ◽  
Lateral Forces ◽  
Concrete Elements

Experimental studies have been carried out to study the effect of longitudinal compression on the strength of the wall of I-beams of reinforced concrete beams.It has been established that with the central application of a longitudinal compressive force, the strength of the wall of I-beams of reinforced concrete beams with an alternating diagram of bending moments in the zone of action of transverse forces practically depends little on the degree of longitudinal compression.A comparative analysis of the results obtained with the results of similar experimental studies carried out on I-beam reinforced concrete beams with an unambiguous diagram of bending moments in the zone of action of shear forces is carried out.

scholarly journals THE STUDY OF LEVEL FORMATION AND DISCLOSURE OF NORMAL CRACKS IN REINFORCED CONCRETE ELEMENTS

2020 ◽  
Vol 4 (157) ◽  
pp. 18-24
Author(s):  
O. Romashko-Maistruk
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Experimental Studies ◽  
Nonlinear Function ◽  
Reinforced Concrete Beams ◽  
The Real ◽  
European Standards ◽  
And Storage ◽  
Concrete Elements ◽  
Formation Step

This article is devoted to the study of the main patterns of normal cracks multilevel formation in reinforced concrete elements and structures. A critical analysis of the latest publications related to the theme of these studies is carried out. The classification is carried out and the main shortcomings of the known works on the four identified areas of research are identified. The most important elements of the method of reinforced concrete beams experimental research are developed and briefly described. The main characteristics of the prototypes, the conditions for their manufacture and storage are given. The most important results of testing reinforced concrete beams, concerning the main parameters and characteristics of level formation and crack disclosure are highlighted. It was confirmed that the process of normal cracks formation is indeed multilevel and is accompanied by a gradual disruption of the bond between reinforcement and concrete. According to the results of experimental studies, it has been established that in the real design of bending reinforced concrete elements, when calculating their crack resistance, it is possible to restrict oneself to only 2 levels of normal cracking. The calculation of the step and normal cracks opening width in beams research was carried out according to the real multilevel and traditional "one-level" schemes of their formation. These calculations were carried out according to the author's general and simplified methods, according to a method that uses a linear function of the average adhesion stresses of reinforcement with concrete, according to the methods of current domestic and European standards and building rules. Their statistical comparison with the experimental studies results confirmed the effectiveness of those calculation methods in which the crack formation step is directly related to the basic laws and parameters of reinforcement to concrete adhesion. The results of this comparison showed that the author's general method, based on the use of a nonlinear function of the reinforcement with concrete average adhesion stresses, turned out to be the most accurate. Keywords: reinforced concrete, elements, adhesion, reinforcement, cracks, levels of formation, step, width.

scholarly journals Bearing capacity of damaged reinforced concrete beams strengthened with metal casing

2021 ◽  
Vol 61 (6) ◽  
pp. 703-721
Author(s):  
Irina Karpiuk ◽  
Denis Danilenko ◽  
Vasyl Karpiuk ◽  
Anna Danilenko ◽  
Tatiana Lyashenko
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Metal Casing ◽  
Damaged Beams ◽  
High Level ◽  
Design Factors ◽  
Concrete Elements ◽  
Inclined Cracks

Experimental data on the bearing capacity of damaged reinforced concrete beams with the dimensions of 2000×200×100 mm, reinforced with prestressed metal casings, are presented. Damaging in the form of through normal and crossing inclined cracks, as well as excessive vertical moving of the beam were obtained during previous tests for the effect of high-level transverse alternating loads.The authors of the article have developed a method and equipment for restoring and strengthening damaged reinforced concrete beams using a casing. Beams are manufactured and tested in accordance with the three-level design of an experiment.Previously damaged and reduced to the ultimate (pre-emergency) state, the beams were strengthened with the declared method and equipment, and then retested. New data on the bearing capacity of ordinary and damaged beams, as well as reinforced concrete elements strengthened with casings and tested for the action of transverse forces and bending moments were obtained. The research results are presented in the form of experimental-statistical dependences of the bearing capacity of the support areas, deformability and crack resistance of the investigated elements on the ratio of the most significant design factors and external factors. A comparative analysis of the influence of these factors on the main parameters of the bearing capacity of ordinary as well as previously damaged and then strengthened test beams is carried out.The possibility and appropriateness of using the proposed method of strengthening reinforced concrete beams damaged by through normal and cross-inclined force cracks in the conditions of an existing production has been experimentally proved.

scholarly journals Analysis of Crack Width Development in Reinforced Concrete Beams

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3043
Author(s):  
Barbara Goszczyńska ◽  
Wiesław Trąmpczyński ◽  
Justyna Tworzewska
Keyword(s):  
Reinforced Concrete ◽  
Crack Width ◽  
Crack Formation ◽  
Concrete Beams ◽  
Concrete Structures ◽  
Diagnostic Methods ◽  
Reinforced Concrete Beams ◽  
Reinforced Concrete Structures ◽  
Maximum Crack ◽  
Concrete Elements

The reliability and durability of reinforced concrete structures depend on the amount of concrete cracking. The risk associated with cracks generates a need for diagnostic methods for the evaluation of reinforced concrete structures. This paper presents the results of a study of 10 single-span reinforced concrete beams to follow the process of crack formation and changes in their width. The beams were loaded to failure with two forces in a monotonic manner with unloading and in a cyclic manner. Continuous observation of the crack formation process was provided by the digital image correlation system. The simplified method for estimating the maximum crack width is proposed. The presented results confirmed the stochastic character of the process of crack formation and development. The maximum crack widths calculated on the basis of the proposed formula were on the safe side in relation to those calculated according to Eurocode 2. It was also confirmed that the distances between cracks do not depend on the loading manner. Hence the density function describing the distribution of distances between cracks can be used to assess the condition of reinforced concrete elements. The research has also shown the suitability of the DIC system (ARAMIS) for testing concrete elements.

Laboratory Tests of Reinforced Concrete Beams with the Use of Operational Modal Analysis

2016 ◽  
Vol 866 ◽  
pp. 124-128 ◽  
Author(s):  
Michał Musiał
Keyword(s):  
Reinforced Concrete ◽  
Modal Analysis ◽  
Laboratory Tests ◽  
Concrete Beams ◽  
Test Stand ◽  
Operational Modal Analysis ◽  
Reinforced Concrete Beams ◽  
Concrete Elements ◽  
Selection Of

This paper presents the potential for the use of operational modal analysis (OMA) in the testing of reinforced concrete elements. The main difficulties encountered by the author when carrying his own experiments in this regard are described. The investigations carried out as part of this research and reported here covered: the identification and selection of a proper test stand, the effect of the loading advancement degree on the eigenfrequencies and damping of reinforced concrete beams. In addition, general tips on the testing of reinforced concrete elements with the use of OMA, which can be useful for conducting other experiments of this type, are included.

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