scholarly journals Thermomechanical analysis of reinforced concrete columns exposed to fire

2020 ◽  
Vol 13 (4) ◽  
Author(s):  
Matheus Wanglon Ferreira ◽  
Luiz Carlos Pinto da Silva Filho ◽  
Mauro de Vasconcellos Real
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Three Dimensional ◽  
Concrete Columns ◽  
Thermomechanical Analysis ◽  
Structural Behavior ◽  
Mechanical Resistance ◽  
Reinforced Concrete Columns ◽  
Proposed Model ◽  
Main Factors

ABSTRACT: A three-dimensional (3D) transient numerical model for thermomechanical analysis developed with Finite Element Method (FEM) using the software ANSYS 19.1 is exposed in this paper. The proposed model aims to predict the structural behavior of reinforced concrete columns in a fire situation since it is known that high temperatures significantly reduce their mechanical resistance. For this, the main factors that govern their structural behavior should be considered. Analyses obtained by the proposed model were validated with results from experimental data, evidencing a good correlation between numerical and experimental fields.

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.

scholarly journals CARRYING CAPACITY OF DAMAGED REINFORCED CONCRETE TWO-TUBE COLUMNS

2021 ◽  
pp. 18-27
Author(s):  
Ye.V. Klymenko ◽  
◽  
N.R. Antoniuk ◽  
E.V. Maksiuta ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Strain State ◽  
Concrete Columns ◽  
Stress Strain ◽  
Reinforced Concrete Columns ◽  
Stress Strain State ◽  
Relative Eccentricity ◽  
Main Factors ◽  
Damage Front

Abstract. The article presents the results of experimental and theoretical studies of the work, the parameters of the stress-strain state and the methodology for calculating the residual bearing capacity of reinforced concrete I-section columns damaged during operation and combat operations. The analysis of the literature on this subject made it possible to study the main factors affecting the residual bearing capacity, namely: the depth of damage; the angle of inclination of the damage front; relative eccentricity of application of external compressive force. A three-factor three-level experimental design has been developed. The conducted field tests of prototypes of damaged reinforced concrete columns made it possible to determine the parameters of the stress-strain state of damaged elements and their actual residual bearing capacity. On the basis of the performed experimental-statistical modeling, the main factors influencing the residual bearing capacity of damaged elements have been established. The prerequisites for calculating damaged reinforced concrete I-beams are proposed and equilibrium equations are drawn up. The proposals set out in the article are based on the main provisions of the current norms and expand the effect of their use. The analysis of influence of various factors on bearing capacity of the damaged I-beam reinforced concrete columns is carried out. It was found that the columns can withstand a maximum destructive load of 1738 kN at an angle of inclination of the damage front of 60о and in the absence of relative eccentricity. And the least destructive load columns can withstand in the absence of the angle of the damage front, and the relative eccentricity will be 1/8 of the applied load. On the basis of the conducted researches the technique of definition of reliably substantiated residual bearing capacity of reinforced concrete compressed elements of a T-profile profile damaged in the course of operation is developed. This makes it possible to determine the possibility of further trouble-free operation of structures or the need for their reinforcement or reconstruction.

Study of the residual axial capacities of shear-damaged reinforced concrete columns: Part 2—experimental verification of an evaluation model

2018 ◽  
Vol 22 (2) ◽  
pp. 459-472
Author(s):  
Yong Yang ◽  
Kazuto Matsukawa ◽  
Ho Choi ◽  
Yoshiaki Nakano
Keyword(s):  
Reinforced Concrete ◽  
Evaluation Model ◽  
Concrete Columns ◽  
Experimental Program ◽  
Transverse Reinforcement ◽  
Concrete Core ◽  
Reinforced Concrete Columns ◽  
Damage Pattern ◽  
Axial Capacity ◽  
Proposed Model

This article presents an experimental program to further verify the arch resistance model, which was proposed for evaluating the residual axial capacities of shear-damaged reinforced concrete columns in part 1 of the companion papers. Three reinforced concrete columns with different transverse reinforcement ratios are designed and tested up to axial collapse under different axial force levels. Based on the experimental results, the transverse reinforcement within the shear-damaged region of the designed specimens is confirmed to be able to fully develop their strength at axial collapse. With regard to the evaluation of residual axial capacities, when the damage pattern of the concrete core is consistent with that described in the proposed model, the residual axial capacity of the column along with the included two contributions of the concrete core and longitudinal bars are estimated with a high level of accuracy. When the damage pattern of the concrete core is not completely consistent with that described in the proposed model, although the contribution of the concrete core is not accurately estimated, the contribution of the longitudinal bars is still accurately evaluated. Furthermore, because of the low percentage of the contribution of the concrete core, the damage pattern of the concrete core has little effect on the evaluation accuracy of the residual axial capacity of the column. Thus, using the proposed model, the residual axial capacities of the columns with slightly different damage patterns of the concrete core are still estimated with a high accuracy in this experimental program.

Study of the residual axial capacities of shear-damaged reinforced concrete columns: Part 1—development of an evaluation model

2018 ◽  
Vol 22 (2) ◽  
pp. 311-322
Author(s):  
Yong Yang ◽  
Kazuto Matsukawa ◽  
Ho Choi ◽  
Yoshiaki Nakano
Keyword(s):  
Reinforced Concrete ◽  
Concrete Columns ◽  
Experimental Program ◽  
Collapse Mechanism ◽  
Reinforced Concrete Column ◽  
Reinforced Concrete Columns ◽  
Experimental Database ◽  
Axial Capacity ◽  
Proposed Model ◽  
Resistance Model

This is the first of two companion papers addressing the residual axial capacities of shear-damaged reinforced concrete columns. To evaluate the residual axial capacity, this article presents an arch resistance model that is based on the theory of mechanics and can reasonably explain the collapse mechanism of shear-damaged reinforced concrete columns. In the proposed model, the residual axial capacity of the column is evaluated by considering the interaction between the contributions of the longitudinal bars and the concrete core rather than by simply adding the two contributions together. The proposed model is also verified using an experimental database of shear-damaged reinforced concrete column specimens compiled from previous studies. The result shows that the proposed arch resistance model has an improved level of accuracy for evaluating the residual axial capacities of most column specimens. However, because the available information about column specimens in the compiled experimental database is limited, it is difficult to further verify the proposed model, and a new experimental program will be presented in Part 2.

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