scholarly journals DETERMINATION OF CRACK RESISTANCE OF PRESTRESSED REINFORCED CONCRETE BEAMS OF TRAPEZOIDAL CROSS-SECTION

2021 ◽  
Vol 6 (11) ◽  
pp. 41-48
Author(s):  
Y. Nikulina
Keyword(s):  
Reinforced Concrete ◽  
Crack Resistance ◽  
Cross Section ◽  
Concrete Beams ◽  
Computer Calculation ◽  
Reinforced Concrete Beams ◽  
Deformation Model ◽  
Resource Saving ◽  
Trapezoidal Cross Section ◽  
Deformation Diagrams

Beams of a trapezoidal cross-section with a wide upper edge with prestressed reinforcement combine positive qualities in terms of strength, crack resistance, deformability and resource saving, which allows them to cover significant spans of multi-storey buildings. To develop a method for calculating the moment of cracking in these structures, a nonlinear deformation model was adopted, which includes equilibrium equations, conditions for the linear distribution of relative deformations along the height of the element section, and refined deformation diagrams of concrete and reinforcement. Concrete state diagrams are assumed to be nonlinear without a falling branch. To describe the deformation diagrams of high-strength and conventional reinforcement, a universal dependence is adopted, consisting of one linear and two nonlinear equations, in which the calculation of individual parameters is performed using different formulas. For the initial stage of the crack formation process, a design scheme is presented, in accordance with which the necessary equations and ratios are drawn up in relation to the considered prestressed reinforced concrete beam of a trapezoidal cross-section. The purpose of the study, in addition to developing a calculation methodology, was also the development of an algorithm and a computer calculation program. To obtain and analyze the results, a numerical experiment was carried out, the results of which are presented in tabular form. Due to the fact that the calculation method was built without involving empirical dependencies, the possibility of its application to determine the crack resistance of prestressed reinforced concrete beams of trapezoidal cross-section for any class of concrete and reinforcement was confirmed.

scholarly journals Assessing the Instantaneous Stiffness of Cracked Reinforced Concrete Beams Based on a Gradual Change in Strain Distributions

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Chunyu Fu ◽  
Dawei Tong ◽  
Yuyang Wang
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Beams ◽  
Internal Force ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Gradual Change ◽  
Concrete Cracking ◽  
Good Agreement

Concrete cracking causes a gradual change in strain distributions along the cross section height of reinforced concrete beams, which will finally affect their instantaneous stiffness. A method for assessing the stiffness is proposed based on the gradual change, which is considered through modeling different strain distributions for key sections in cracked regions. Internal force equilibria are adopted to find a solution to top strains and neutral axes in the models, and then the inertias of the key sections are calculated to assess the beam stiffness. The proposed method has been validated using experimental results obtained from tests on five reinforced concrete beams. The predicted stiffness and displacements are shown to provide a good agreement with experimental data. The instantaneous stiffness is proven to greatly depend on the crack number and depth. This dependence can be exactly reflected by the proposed method through simulating the gradual change in concrete strain distributions.

Flexural capacity and design of hybrid FRP-steel-reinforced concrete beams

2019 ◽  
Vol 23 (7) ◽  
pp. 1290-1304
Author(s):  
Yang Yang ◽  
Ze-Yang Sun ◽  
Gang Wu ◽  
Da-Fu Cao ◽  
Zhi-Qin Zhang
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
Steel Reinforced Concrete ◽  
Reinforced Polymer ◽  
The Cross

This study presents a design method for hybrid fiber-reinforced-polymer-steel-reinforced concrete beams by an optimized analysis of the cross section. First, the relationships among the energy consumption, the bearing capacity, and the reinforcement ratio are analyzed; then, the parameters of the cross section are determined. Comparisons between the available theoretical and experimental results show that the designed hybrid fiber-reinforced-polymer-steel-reinforced concrete beams with a low area ratio between the fiber-reinforced polymer and the steel reinforcement could meet the required carrying capacity and exhibited high ductility.

Experimental Study on Reinforcement of Failure Reinforced Concrete Beams

2013 ◽  
Vol 275-277 ◽  
pp. 1264-1267
Author(s):  
Qian Chen ◽  
Ling Yong Liu ◽  
Yang Jun Meng
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Epoxy Resin ◽  
Cross Section ◽  
Concrete Beams ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Carbon Cloth ◽  
Structural Failure

Through repair and reinforcement of breaking reinforced concrete beams by epoxy resin and carbon cloth, and its experiment, the crack and deformation and bearing capacity as well as ductility of such beams are obtained. Experimental results show that the ultimate bearing capacity of beams after reinforcement increased by 210%, the structure ductility fell by 170%, structural failure form is similar to failure in normal cross section.

scholarly journals A Parametrical Analysis for the Rotational Ductility of Reinforced Concrete Beams

2013 ◽  
Vol 7 (1) ◽  
pp. 242-253
Author(s):  
Domenico Raffaele ◽  
Giuseppina Uva ◽  
Francesco Porco ◽  
Andrea Fiore
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Beams ◽  
Closed Form Solution ◽  
Form Solution ◽  
Reinforced Concrete Beams ◽  
Shear Cracks ◽  
Technical Standards ◽  
Mechanical Reinforcement ◽  
Plastic Rotation

The assessment of the plastic rotation of reinforced concrete beams is an essential aspect to avoid structural brittle collapses. The value actually available can be generally determined as sum of two different components. The first, due to bending, the second for inclined shear cracks. This paper presents a simplified model which provides the flexural plastic rotation of the rectangular beams with a ``closed-form solution''. The approach is substantially dimensionless and includes main influencing factors the cross -section, as mechanical material properties, ductility, geometrical and mechanical reinforcement ratio, confinement effects. In closing, in order to appreciate the reliability of the procedure, a comparison with models proposed by international technical standards is made.

scholarly journals Reinforced concrete beams on yielding supports with thrust under dynamic load

2021 ◽  
Vol 23 (6) ◽  
pp. 143-156
Author(s):  
O. G. O.G. Kumpyak ◽  
D. R. Galyautdinov
Keyword(s):  
Reinforced Concrete ◽  
Crack Resistance ◽  
Dynamic Load ◽  
Concrete Beam ◽  
Energy Intensity ◽  
Concrete Beams ◽  
Horizontal Displacement ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams ◽  
Positive Effect

Reinforced concrete beam with limited horizontal displacement on yielding supports under dynamic loading require considering the thrust response. The thrust presence significantly increases the beam strength and crack resistance. The use of yielding supports increases their energy intensity. The purpose of the paper is the experimental study of using yielding supports under the dynamic load conditions. The experimental results concern the reinforced concrete beam with yielding supports with a thrust under the dynamic load. The paper shows the effect from yielding supports on the strength, deformability, and crack resistance of reinforced concrete beams. The obtained results indicate to a positive effect form the use of yielding supports of the beam under the dynamic load.

scholarly journals Calculation of damage RC constructions according to deformation model

2020 ◽  
Vol 2020 (2) ◽  
pp. 99-106
Author(s):  
Yaroslav Blikharskyy ◽  
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Concrete Structures ◽  
Physical And Mechanical Properties ◽  
Reinforced Concrete Beams ◽  
Core Material ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
The Impact

This article presents results of a theoretical study of reinforced concrete beams with damaged reinforcement. The change of micro-hardness of a reinforcing rebar’s with a diameter of 20 mm of A500C steel in the radial direction is investigated and the thickness of the heat-strengthened layer is established. It is established that the thickness of the thermo-strengthened steel layer of the reinforcing bar with a diameter of 20 mm of A500C is approximately 3 mm. It is shown that the strength characteristics of this layer are on 50% higher compared to the core material of the rebar, while the plasticity characteristics are lower. The aim of the work is to determine the strength and deformability of reinforced concrete structures without damaging the reinforcement and in case of damage. Determining the impact of changes in the physical characteristics of reinforcement on the damage of reinforced concrete structures, according to the calculation to the valid norms, in accordance with the deformation model. To achieve the goal of the work, theoretical calculations of reinforced concrete beams were performed according to the deformation model, according to valid norms. This technique uses nonlinear strain diagrams of concrete and rebar and is based on an iterative method. According to the research program 3 beam samples were calculated. Among them were undamaged control sample with single load bearing reinforcement of ∅20 mm diameter – BC-1; sample with ∅20 mm reinforcement with damages about 40% without changes in the physical and mechanical properties of reinforcement – BD-2 and sample with ∅20 mm reinforcement with damages about 40% with changes in the physical and mechanical properties of reinforcement – BD-3. The influence of change of physical and mechanical characteristics of rebar’s on bearing capacity of the damaged reinforced concrete beams is established.

STUDIES OF DEFLECTIONS OF STATICALLY DETERMINED REINFORCED CONCRETE BEAMS BASED ON A NONLINEAR DEFORMATION MODEL

2017 ◽  
Vol 7 (4) ◽  
pp. 9-13
Author(s):  
Denis A. PANFILOV ◽  
Vladimir Yu. CHEGLINTSEV ◽  
Vyacheslav V. ROMANCHIKOV ◽  
Yury V. ZHILTSOV
Keyword(s):  
Reinforced Concrete ◽  
Numerical Experiment ◽  
Nonlinear Deformation ◽  
Concrete Beams ◽  
Experimental Studies ◽  
Reinforced Concrete Beams ◽  
Deformation Model ◽  
Theoretical Studies ◽  
Program Complex ◽  
Nonlinear Deformation Model

In this paper theoretical studies of statically determinated bending reinforced concrete beams of rectangular cross-section on deformation indexes under the eff ect of a short-time uniformly distributed load are viewed. These theoretical studies are based on the main points of the nonlinear deformation model that takes into account the nonlinear work of concrete and fi tments taking into account discrete cracking. The results of calculating the deformation of beams by the method of SP 63.13330.2012 and by authors’ method are proposed as well as the results of a numerical experiment with the identifi cation of the stress-strain state of statically determinated beams in the form of a fi nite element model in the program complex «Lira CAD-2017R3» using a linear and non-linear sett ing of characteristics of concrete and reinforcement. Based on the results of theoretical studies, the calculation results by the methodology of the current standard with a numerical experiment, as well as with the authors’ calculation methodology are compared. All calculations and loading schemes in this technique are given taking into account the possibility of further experimental studies.

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