Bearing Capacity Of Centrally Compressed Reinforced Concrete Elements Corrosion-Damaged As A Result Of Fire Exposure

2019 ◽  
pp. 35-39
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Cross Section ◽  
Protective Layer ◽  
Temperature Fields ◽  
Reinforced Concrete Column ◽  
The Cross ◽  
Concrete Elements ◽  
Technical Calculation

Determination of the bearing capacity of the elements damaged as a result of fire effect depends on the accuracy of the thermo-technical calculation. After this calculation, the distribution of the temperature field over the cross section of the element and the strength characteristics depending on it are determined. The temperature distribution over the cross section of the element depends on such parameters as heat capacity and thermal conductivity of parts of the section, the spatial position of the structure, its humidity. As part of this work, heat engineering calculations of the cross section of the reinforced concrete column were performed with various options of the cross section - with and without a protective layer, taking into account the thermal performance of all cross section components (reinforcement, concrete and corrosion) and excluding corrosion and reinforcement. Based on the obtained temperature fields, the bearing capacity and its percentage ratio were calculated. The main conclusion is that the bearing capacity of the centrally compressed corrosion-damaged elements is significantly influenced by the factor of separation of the protective layer of concrete, as well as thermal-technical characteristics of materials.

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.

Fire Resistance of Reinforced Concrete Corrosion-Damaged Columns of the "Standard" Fire

2019 ◽  
Vol 828 ◽  
pp. 163-169
Author(s):  
Ashot Georgievich Tamrazyan ◽  
Micheal Sergeevich Mineev ◽  
Aishat Urasheva
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Fire Resistance ◽  
Protective Layer ◽  
Operating Conditions ◽  
Corrosive Environment ◽  
Reinforced Concrete Column ◽  
Cross Sectional ◽  
Standard Fire ◽  
The Cross

The article describes the features of the effect of corrosion of reinforcement on the bearing capacity of reinforced concrete columns in a "standard" fire. On the basis of the standard calculation method, the fire resistance of the column was estimated under a four-sided fire effect taking into account the different duration of the fire. The study examined the operation of the column in a corrosive environment, it was assumed that the initiation of corrosion of concrete and reinforcement will occur after 10 years of exploitation. It was found that the destruction of concrete protective layer 25 mm thick in a medium aggressive environment will occur after 25 years, and the diameter of the reinforcement during this period will decrease by 20%. To compare the results, a reinforced concrete column with a section of 400x400mm was calculated under the influence of a “standard” fire under normal operating conditions and taking into account work in a corrosive environment. The results of heat engineering calculations are presented, where the temperature changes in the reinforcement depending on the heating time and reduction of the protective layer thickness, as well as the change in the diameter of the reinforcement and its effect on the bearing capacity are shown. It has been established that reducing the cross-sectional area of the working reinforcement and reducing the cross-sectional dimensions of the column due to the occurring corrosion processes leads to a decrease in the fire resistance limit on the loss of bearing capacity by 58%.

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

2021 ◽  
pp. 30-44
Author(s):  
L. R. Mailyan ◽  
S. A. Stel'makh ◽  
E. M. Shcherban ◽  
M. P. Nazhuev
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Cross Section ◽  
Concrete Columns ◽  
Reinforced Concrete Columns ◽  
The Cross ◽  
Concrete Elements ◽  
Diagram Approach

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 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.

Stimulation Analysis of High Temperature Bearing Capacity of Steel Reinforced Concrete Column Strengthened by CFRP

2013 ◽  
Vol 351-352 ◽  
pp. 401-405
Author(s):  
Cheng Zhu Qiu ◽  
Gang Yang
Keyword(s):  
Reinforced Concrete ◽  
High Temperature ◽  
Bearing Capacity ◽  
Cross Section ◽  
Concrete Columns ◽  
Concrete Column ◽  
Reinforced Concrete Column ◽  
Simulation Research ◽  
Steel Reinforced Concrete ◽  
Finite Element Software

The steel reinforced concrete column is one of the important members for structures, it is essential to study the high temperature performance of concrete column. The numerical simulation research is done using finite element software ANSYS. Under the high temperature, the analysis of the compressive bearing capacity and flexural capacity of the concrete columns strengthened by CFRP is done, and the compressive bearing capacities of different cross-section concrete columns strengthened with CFRP are tested.

Research on Compression Failure and Size Effect in High Strength Eccentric Reinforced Concrete Column

2012 ◽  
Vol 193-194 ◽  
pp. 656-661 ◽  
Author(s):  
Cedrick Mbang Matamb ◽  
Xiu Li Du ◽  
Jian Wei Zhang
Keyword(s):  
Reinforced Concrete ◽  
Size Effect ◽  
Bearing Capacity ◽  
Cross Section ◽  
High Strength ◽  
Concrete Column ◽  
Reinforced Concrete Column ◽  
Failure Characteristics ◽  
Compression Failure ◽  
Characteristics Analysis

This test was investigated on the compression failure in eccentric reinforced concrete square cross-section. In total twelve different scale specimens were eccentrically compressed with size of: 200×200mm; 400×400mm; 800×800mm. specimens were divided into 3 groups with 4 each. Only six columns have been investigated in this paper thus a column by eccentricity. The main point were based on the existence of size effect phenomenon on cross-section components collapsed with different sizes to the ultimate bearing capacity and the cross-section strain, ductility, deflection, and other failure characteristics. Analysis of the experimental data’s showed that the size effect phenomenon exists.

scholarly journals ASSESSMENT OF THE DEPTH AND RATE OF CORROSION IN STEEL REINFORCEMENT OF REINFORCED CONCRETE CULVERTS

2020 ◽  
Author(s):  
Alexandr Vasiliev ◽  
Svetlana Daškevič
Keyword(s):  
Reinforced Concrete ◽  
Protective Layer ◽  
Corrosion Damage ◽  
Steel Reinforcement ◽  
Operating Conditions ◽  
Protective Properties ◽  
Open Atmosphere ◽  
Concrete Elements ◽  
Corrosion State

Based on the results of many research years on concrete carbonisation: both immediately after manufacture (using heat-moisture treatment) and in reinforced concrete elements operated for the periods of various length (in an open atmosphere); the effect of carbonisation on the change in the protective properties of concrete in relation to steel reinforcement; for determination of the dependence of the corrosion state of steel reinforcement on the degree of concrete carbonisation in the area of steel reinforcement; the obtained regression dependences of the change (by time in the cross section) of the degree of concrete carbonisation of various classes in strength, – the analysis of the time of the onset of the boundary values of the degrees of concrete carbonisation (strength classes C12/15–C30/37) for the operating conditions of the open atmosphere was performed. Based on it, the regression dependences of the time variation of the depth of corrosion damage of steel reinforcement were construed (for fixed thicknesses of the concrete protective layer). The obtained nature of dependences made it possible to offer, in a general form, the regression dependences of the depth of corrosion damage and corrosion rate of steel reinforcement for concretes (strength classes C12/15–C30/37) for operating conditions in open atmosphere.

Bearing Capacity Analysis of the Cross-Section Steel Reinforced Concrete Column in Different Parameters

2013 ◽  
Vol 438-439 ◽  
pp. 526-529
Author(s):  
Ri Liang Li ◽  
Ya Feng Xu ◽  
Shou Yan Bai
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Axial Compression ◽  
Compression Ratio ◽  
Large Scale ◽  
Displacement Curve ◽  
Reinforced Concrete Column ◽  
Steel Reinforced Concrete ◽  
Axial Compression Ratio ◽  
The Cross

This paper uses the large-scale finite element analysis software ABAQUS to simulate 12 cross steel reinforced concrete special-shaped columns with the control variables of axial compression ratio and rate of steel bone, and subjected to the monotonic load with 20mm horizontal displacement. 6 columns work under the different axial compression ratio of 0.0, 0.4, 0.5, 0.6, 0.7 and 0.8. Other 6 columns are made of different rates of steel bone with different steel bone thickness of 0mm, 2mm, 4mm and 6mm, 8mm and 10mm, and subject to vertical axial force in axial compression ratio of 0.3. By simulating, we obtain the load - displacement curve of different axial compression ratios and different rates of steel bone, and analyze the effect of the bearing capacity of the cross steel reinforced concrete special-shaped columns in different parameters. The results show that the bearing capacities of the columns decrease with the increasing ratio of axial compression, and increase with the increasing rate of steel bone.

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