scholarly journals THE EXPERIMENTAL RESEARCHES OF REINFORCED CONCRETE I-BEAM ELEMENTS WITH NORMAL CRACKS WHEN TURNING

2019 ◽  
Vol 2 (53) ◽  
pp. 171-176
Author(s):  
Olga Orlova
Keyword(s):  
Reinforced Concrete ◽  
Twist Angle ◽  
Longitudinal Reinforcement ◽  
External Torque ◽  
Beam Elements ◽  
The Difference ◽  
The Moment ◽  
Nonlinear Deformations ◽  
Experimental Researches ◽  
Concrete Elements

The data of experimental researches of the rigidity of reinforced concrete I-beam elements with normal cracks at the action on them of the twisting moment have resulted in this paper. It is shown that the dependence "torque-twist angle" is almost linear. Significant nonlinear deformations appear in the last stages of loading before failure. Therefore at normative torques, it is recommended to consider the work of reinforced concrete elements of the I-beam cross-section with normal cracks linear. It is shown that the presence of longitudinal reinforcement affects the strength and rigidity of beams with normal cracks. Quite a large part of the external torque is perceived by the pin forces in the longitudinal reinforcement. The difference between the external torque and the moment of the pin forces in the armature is perceived by the upper shelf of the I-beam element. In the absence of longitudinal reinforcement, the upper shelf can collapse at loads much smaller than the destructive load of beams with longitudinal reinforcement.

Long-Term Deformations of Strengthened Reinforced Concrete Linear Elements

2016 ◽  
Vol 691 ◽  
pp. 51-60 ◽  
Author(s):  
Martin Krizma ◽  
Lubomir Bolha
Keyword(s):  
Reinforced Concrete ◽  
Long Term Results ◽  
Short Term ◽  
Limit States ◽  
Linear Elements ◽  
Repeated Load ◽  
The Moment ◽  
Concrete Elements ◽  
Fiber Fabric

The issue of strengthening the damaged linear reinforced concrete elements have been engaged since 2008. We focused on the analysis of resistance and the characteristics of limit states of serviceability in the damaged and subsequently strengthened elements at a short-term loading. In the introduction phase, the strengthening of the elements was carried out with the following procedures – installation of an overlayer on the coupling board or a combination of the board and use of glass – fiber fabric (GFRP). The strengthening was also affected by the type of contact (reinforced/non-reinforced) – the deformed element/coupling board and its effect on resistance, type of deformation and serviceability. In the non-reinforced contact, we applied some of the types of adjustments to the surface of the strengthened element. At the moment, we are dealing with the effects of time and repeated load on the strengthened elements. The results correspond to the reinforced contact. The values are compared with the short-term results of the strengthened beams and with the long-term results of the beams prepared for strengthening.

scholarly journals MODELS OF BAY REINFORCED CONCRETE ELEMENTS RESISTANCE AT ACTION OF CYCLE PERMANENT SIGN HIGH LEVEL FORCES

2018 ◽  
Vol 1 (50) ◽  
pp. 112-123 ◽  
Author(s):  
V. M. Karpiuk ◽  
A. I. Kostiuk ◽  
Yu. A. Somina
Keyword(s):  
Reinforced Concrete ◽  
Strain State ◽  
Physical Models ◽  
Cyclic Loads ◽  
Longitudinal Reinforcement ◽  
Calculation Methods ◽  
Cyclic Action ◽  
High Level ◽  
Creep Deformations ◽  
Concrete Elements

The reinforced concrete span beam structures work with small, middle and large shear spans under the action of cyclic loads of high levels is investigated. It is established that researches of physical models development of bending reinforced concrete elements fatigue resistance to the cyclic action of transverse forces and calculation methods on its base are important and advisable due to following features of said load type: the nonlinearity of deformation, damage accumulation in the form of fatigue micro- and macrocracks, fatigue destruction of materials etc. The key expressions of the concrete endurance limits definition (objective strength), longitudinal reinforcement, anchoring of longitudinal reinforcement, which consists the endurance of whole construction are determined. Also the role and the features of influence of vibro-creep deformations on the change mechanics of stress-strain state of concrete and reinforcement of research elements are investigated.

scholarly journals Construction of the interaction curve of concrete-encased composite columns based on the deformation domains of reinforced concrete sections

2015 ◽  
Vol 8 (4) ◽  
pp. 447-466 ◽  
Author(s):  
P. A. S. ROCHA ◽  
K. I. DA SILVA
Keyword(s):  
Reinforced Concrete ◽  
Computer Program ◽  
Axial Force ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Longitudinal Reinforcement ◽  
Limit Values ◽  
Composite Columns ◽  
Interaction Curves ◽  
The Moment

AbstractThis paper proposes a methodology for obtaining the interaction curve for composite steel-concrete sections subject to combined compression and bending based on the deformation domains of reinforced concrete structures defined by ABNT NBR 6118 [1]. For this, were developed expressions for the axial force, the moment and the strains of concrete, longitudinal reinforcement and the elements comprising the metal profile in each deformation domain.Based on these expressions a computer program called MDCOMP (2014) was created. In this study the same limit values of longitudinal reinforcement strain defined by ABNT NBR 6118 [1] were used for the steel profile strains. To verify the numerical implementations performed, the interaction curves and the plastic resistance of the section obtained by MDCOMP program were compared with those determined from the recommendations of Eurocode 4 [2], of ABNT NBR 8800 [3] or literature responses.

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 Analisis Kapasitas Lentur Balok Beton Tulang Berongga Akibat Perbedaan Kuat Tarik Tulangan

2021 ◽  
Vol 21 (3) ◽  
pp. 681-689
Author(s):  
Syahrul Sariman ◽  
Rita Irmawaty
Keyword(s):  
Tensile Strength ◽  
Reinforced Concrete ◽  
Carrying Capacity ◽  
Concrete Beams ◽  
Bending Moment ◽  
Reinforced Concrete Beams ◽  
The Difference ◽  
The Moment

Penelitian ini bertujuan menetapkan karakteristik lentur balok beton tulang berongga akibat perbedaan kuat tarik tulangan.  Dalam penelitian ini  digunakan balok beton bertulang dengan mutu beton f’c=27Mpa dan dimensi  150x350mm, Panjang 3300mm dengan tulangan pokok 3D16mm  dengan kuat leleh fy=475 Mpa (type WS) dan fy=324MPa (type RM). Setiap balok dengan type tulangan yang berbeda  terdiri dari   3 balok yang dibedakan menurut panjang rongganya dan diberi notasi  BR3A,  BR3B dan BR3C.  dengan tinggi rongga tetap : 180mm. Hasil penelitian menunjukkan bahwa  variasi rongga  tidak mempengaruhi kapasitas setiap balok  dalam memikul momen. Perbedaan kapasitas momen lentur disebabkan oleh perbedaan kuat tarik baja tulangan. This study aims to determine the flexural characteristics of hollow reinforced concrete beams due to differences in the tensile strength of reinforcement. In this study used reinforced concrete beams  f'c=26.85 MPa and dimensions 150x350mm, length 3300mm.  Bar reinforcement of  3D16mm with fy=475Mpa  (WStype) and fy=324MPa (RMtype). Each beam with a different type of reinforcement consists  of  3  beams that are distinguished by the length of the hollow which is  namely BR3A, BR3B and  BR3C.  with a fixed hollow  height (180mm). The results showed that hollows variations did not affect the carrying capacity of the moment. Different of  capacity  bending moment is caused by the difference in the tensile strength of the reinforcement

Improvement Of The Method For Calculation Of Reinforced Concrete Bending Elements By Inclined Sections

2019 ◽  
Keyword(s):  
Reinforced Concrete ◽  
Strain State ◽  
Transverse Reinforcement ◽  
Theoretical Studies ◽  
Longitudinal Reinforcement ◽  
Inclined Crack ◽  
Major Factors ◽  
Concrete Elements ◽  
Experimental And Theoretical Studies ◽  
Detailed Picture

Testing of a large number of bending pre-stressed concrete elements and elements without pre-stressing of longitudinal reinforcement with their destruction by inclined sections, as well as analysis of numerous experimental and theoretical studies both domestic and foreign made it possible to obtain a detailed picture of the stress-strain state in concrete and reinforcement in the area of transverse forces action. Values of influence on the bearing capacity of the bending reinforced concrete elements of such factors as cohesion forces of the rough surface of the banks in the inclined crack, the dowel effect of the longitudinal reinforcement at the intersection of its inclined fracture, pre-stress in longitudinal reinforcement, depending on the transverse width of the elements, and in transverse reinforcement, depending on the forces of the elastic compression of concrete by stressed longitudinal reinforcement, etc. are set. According to the research results, it is concluded that it is expedient to improve the method of calculating the strength of bending concrete elements by inclined sections, laid down in the regulations, taking into account the influence of all major factors.

scholarly journals NUMERICAL STUDY OF THE PUNCHING SHEAR MECHANISM FOR THIN AND THICK REINFORCED CONCRETE SLABS

2021 ◽  
Vol 17 (4) ◽  
pp. 91-105
Author(s):  
Oleg Kabantsev ◽  
Sergey Krylov ◽  
Sergey Trofimov
Keyword(s):  
Reinforced Concrete ◽  
Experimental Studies ◽  
Great Influence ◽  
Shear Capacity ◽  
Punching Shear ◽  
Concrete Slabs ◽  
Longitudinal Reinforcement ◽  
Shear Mechanism ◽  
Reinforced Concrete Slabs ◽  
The Difference

The assessment of the punching shear capacity for reinforced concrete slabs, carried out according to the regulatorydocuments of a number of countries, leads to significantly various results. At the same time, the results of thecalculated forecast may have great differences from the experimental data. A great influence on the accuracy of the resultsof the calculated forecast is exerted by the thickness of the examined slabs, as well as the value of longitudinal reinforcement.These parameters determine the features of the mechanisms of destruction of slabs in case of the punching shearmechanism, as indicated by individual interpretations of the results of experimental studies. In order to determine thefeatures of the punching shear mechanism of reinforced concrete slabs of various thicknesses, numerical studies of theprocess of cracking and destruction of slabs of different thicknesses have been performed. Differences in the mechanismof formation and development of cracks in thin and thick slabs are revealed. The paper shows that the behavior of thinand thick slabs has qualitative distinctions at the initial stages of formation and development of the cracks leading todestruction. The authors have also shown the difference between stress-strain state of thick and thin slabs before destruction.In conclusion, it was established that the influence of longitudinal reinforcement on the strength during punching inthick slabs is much less than in thin ones.When evaluating the punching shear capacity of reinforced concrete slabs, the regulatory documents of different countries give significantly different results. In this case, the calculation results may differ significantly from the experimental data. The deterioration of the thickness of the calculated slabs, as well as the value of the longitudinal reinforcement has a great influence on the accuracy of the calculation results. These parameters determine the features of the destruction mechanisms of slabs under punching. This fact is indicated by some interpretations of the results of experimental studies. In order to establish the peculiarities of the punching shear mechanism of reinforced concrete slabs of different thicknesses, a numerical investigation of the cracking and destruction of slabs of different thicknesses have been performed. Differences in the mechanism of formation and development of cracks in thin and thick slabs have been revealed. The paper shows that the behavior of thin and thick slabs has qualitative differences at the initial stages of the cracks formation and development that leads to destruction. The difference between stress-strain state of thick and thin slabs before breaking have been shown. It was found that the effect of longitudinal reinforcement on the punching shear strength in thick slabs is much less than in thin ones.

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%.

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