scholarly journals Analysis of Fire Resistance of Square-Cased Square Steel Tube Reinforced Concrete (ST-RC) Columns

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5541
Author(s):  
Gaoxiong Wang ◽  
Yanhong Bao ◽  
Li Yang ◽  
Yang Yu
Keyword(s):  
Reinforced Concrete ◽  
Fire Resistance ◽  
Slenderness Ratio ◽  
Concrete Strength ◽  
Load Ratio ◽  
Internal Force ◽  
Steel Tube ◽  
Fe Model ◽  
Cross Sectional ◽  
Rc Columns

Based on the finite element (FE) analysis software Abaqus, an FE model of square-cased square steel tube reinforced concrete (ST-RC) columns under the hybridized action of high-temperature and load is established. The accuracy of the FE model is verified using experimental data from existing studies. This model is used to analyze the temperature change, internal force distribution, and failure characteristics of the square-cased square ST-RC columns under the action of fire, as well as the factors affecting the fire resistance limit of the column. The results of FE analysis show that under the action of fire, the maximum internal temperature of the square-cased square ST-RC columns occurs in the corner of the section. Moreover, the stress and strain reach their maximum values at the concrete corner outside the tube. During the heating process, an internal force redistribution occurs in the square-cased square ST-RC column. At the same time, the proportion of the axial force and the bending moment of the reinforced concrete outside the pipe decreases gradually, while the proportion of the internal force of the core concrete-filled steel tube (CFST) increases gradually. In essence, it is a process of load transfer from the high-temperature to the low-temperature zone. In addition, the section size, load ratio, slenderness ratio, cross-sectional core area ratio, steel content, and external concrete strength are the main parameters affecting the fire resistance limit of the square-cased square ST-RC columns. Among them, the cross-sectional core area ratio, section size, steel ratio, and external concrete strength are positively correlated with the fire resistance limit of the composite column. On the contrary, with the increase in the load ratio and the slenderness ratio, the fire resistance limit of the square-cased square ST-RC columns decreases. On this basis, a simplified formula to calculate the fire resistance limit of square-cased square ST-RC columns is proposed. The research results can be used as a theoretical reference for the fire protection design of this kind of structure in practical engineering.

scholarly journals Analysis of Concrete-Filled Steel Tube Reinforced Concrete Column-Steel Reinforced Concrete Beam Plane Frame Structure Subjected to Fire

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yanhong Bao ◽  
Bowen Chen ◽  
Lei Xu
Keyword(s):  
Reinforced Concrete ◽  
Fire Resistance ◽  
Load Ratio ◽  
Reinforced Concrete Beam ◽  
Steel Tube ◽  
Frame Structure ◽  
Fire Load ◽  
Steel Reinforced Concrete ◽  
Plane Frames ◽  
Plane Frame

The ABAQUS finite-element analysis platform was used to understand the mechanical behavior of concrete-filled steel tube reinforced concrete (CFSTRC) columns and steel reinforced concrete (SRC) beam plane frames under fire conditions. Thermal parameters and mechanical constitutive model of steel and concrete materials were reasonably selected, the correct boundary conditions were chosen, and a numerical model for the thermal mechanical coupling of CFSTRC columns and SRC beam plane frame structure was established. The finite-element model was verified from related experimental test results. The failure modes, deformation, and internal force distribution of the CFSTRC column and SRC beam plane frames were analyzed under ISO-834 standard fire conditions and with an external load. The influence of beam and column fire-load ratio on the fire resistance of the frame structure was established, and the fire-resistance differences between the plane frame structures and columns were compared. The CFSTRC column-steel reinforced concrete beam plane frame may undergo beam failure or the column and beam may fail simultaneously. The frame structure fire-resistance decreased with an increase of column and beam fire-load ratio. The column and beam fire-load ratio influence the fire resistance of the frames significantly. In this numerical example, the fire resistance of the frames is less than the single columns. It is suggested that the fire resistance of the frame structure should be considered when a fire-resistant structural engineering design is carried out.

An Experimental Study on the Fire Behavior of CFT Columns under the Constant Axial Loading Condition in Fire

2012 ◽  
Vol 446-449 ◽  
pp. 1298-1306
Author(s):  
Hyung Jun Kim ◽  
Heung Youl Kim ◽  
In Hwan Yeo
Keyword(s):  
Boundary Condition ◽  
Fire Resistance ◽  
Fire Behavior ◽  
Load Ratio ◽  
Steel Tube ◽  
Cross Sectional ◽  
Cross Sectional Size ◽  
Major Factors ◽  
In Fire ◽  
Resistance Performance

The temperature of the steel tube of a CFT column rises rapidly upon a fire causing the deterioration of its strength, while the concrete inside of the tube having large heat capacity provides fire-resistance performance. In order to employ CFT columns as fire-resistant structure, it is necessary to conduct studies on the factors exerting influence on structural capacities and the influence associated with each condition. Concrete’s compressive strength, cross-sectional size, axial load ratio and boundary condition are the major factors which are influential in fire-resistance performance. In particular, boundary condition between columns and beams is one of the major factors which decide fire-resistance performance because it exerts influence on load carrying capacity. The result of the test conducted in this study showed that fire-resistance time of 106 minutes was secured in the specimens with clamped ends and that of 89 minutes in those with pinned ends when cross-sectional size was 360 by 360. In the specimens with cross-sectional size of 280 x 280, fire-resistance time of 113 minutes was secured under the condition of clamped ends and that of 78 minutes was secured under the condition of pinned ends.

Experimental study on the fire resistance of concrete filled steel tube reinforced concrete (CFSTRC) column-RC beam frames

2021 ◽  
pp. 136943322110015
Author(s):  
Lei Xu ◽  
Yan-Hong Bao
Keyword(s):  
Reinforced Concrete ◽  
Cross Sections ◽  
Fire Resistance ◽  
Failure Modes ◽  
Load Ratio ◽  
Steel Tube ◽  
Stiffness Ratio ◽  
Fire Load ◽  
Concrete Core ◽  
Concrete Filled Steel Tube

To reveal the temperature characteristics and mechanical properties of frame structures with concrete filled steel tube reinforced concrete (CFSTRC) columns under fire, the fire resistance of four planar frames consisting of CFSTRC columns and reinforced concrete (RC) beams subjected to ISO-834 standard fire was tested in this study. The test parameters included the column fire load ratio, beam fire load ratio, and beam-to-column linear stiffness ratio. In the test, the temperatures of the column, beam, and slab cross-sections in the joint and nonjoint zones were measured, and the fire resistance, beam and column deformation curves, and failure modes of the frame were investigated. The experimental results showed that the concrete volume was the main factor affecting the temperature distribution on each typical cross-section of the frame: the temperatures at the measuring points of the beam and column in the joint zone were significantly lower than the temperatures at the corresponding points in the nonjoint zone, and the concrete outside the steel tube significantly slowed the propagation of temperature to the steel tube and its concrete core. Hence, there was only a small loss of the bearing capacity of steel tube and the core concrete inside the steel tube. The column fire load ratio, beam fire load ratio, and beam-to-column linear stiffness ratio have obvious influences on the fire resistance: the larger the column fire load ratio or beam fire load ratio, the smaller the fire resistance; and the larger the beam-to-column linear stiffness ratio, the larger the fire resistance.

Dynamic Performance of the Steel Tube Filled with Steel-Reinforced Concrete Finite Element Analysis

2012 ◽  
Vol 490-495 ◽  
pp. 3155-3159
Author(s):  
Xiao Liu ◽  
Min Li
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Slenderness Ratio ◽  
Dynamic Performance ◽  
Concrete Strength ◽  
Steel Tube ◽  
Element Approximation ◽  
Structural Dynamic ◽  
Steel Reinforced Concrete ◽  
Steel Ratio

In order to analyze the dynamic performance of the steel tube filled with steel-reinforced concrete under dynamic loading, the paper based on finite element approximation and inverse power of the iterative algorithm, used FORTUNE language to establish the structural dynamic analysis program. Calculated the critical loads and natural period of vibration and other data of the steel tube filled with steel-reinforced concrete column, and through curve analysis, obtained the rules of the stability of steel and seismic performance on the column from the influence parameter of slenderness ratio , steel ratio , concrete strength and etc. The results show that the slenderness ratio impacts greater than other parameters, so it must be strictly controlled within a certain range; meantime, the results also prove that improving steel ratio and reduce the strength of the concrete is not significant on the earthquake action

Identifying Buckling Resistance of Reinforced Concrete Columns During Inelastic Deformation

2020 ◽  
Vol 20 (03) ◽  
pp. 2050029
Author(s):  
Jian Weng ◽  
Kang Hai Tan ◽  
Chi King Lee
Keyword(s):  
Reinforced Concrete ◽  
Parametric Study ◽  
Inelastic Deformation ◽  
Progressive Collapse ◽  
Slenderness Ratio ◽  
Concrete Strength ◽  
Design Parameters ◽  
Rc Columns ◽  
Inelastic Material ◽  
Buckling Resistance

A simple solution method to identify buckling resistance of reinforced concrete (RC) columns during inelastic deformation is presented. Unlike conventional buckling solution methods, this proposed method predicts inelastic buckling loads of RC columns by directly solving the equilibrium differential equation under buckling. The method considers specific deflection configuration, end restraint conditions and inelastic material properties of the deformed column. In order to evaluate the reliability and accuracy of the proposed method, the results obtained from the purposed method are compared with the test results of eccentrically loaded RC columns. In addition, by using the proposed solution procedure, a parametric study is conducted to investigate the effects of critical RC column design parameters on column buckling behavior and resistance, including slenderness ratio, concrete strength, as well as longitudinal reinforcement and stirrup ratios. The results of the parametric study show that the proposed method is rational and can be adopted to effectively identify buckling resistance of RC columns subjected to inelastic damage, especially when load redistributions have occurred in the structure during progressive collapse.

Nonlinear Structural Analysis of Fire-Exposed Reinforced Concrete Column

2015 ◽  
Vol 1095 ◽  
pp. 267-275
Author(s):  
Li Xian Liu ◽  
Long Lv ◽  
Yan Feng Zhao
Keyword(s):  
Reinforced Concrete ◽  
Structural Analysis ◽  
Computer Program ◽  
Fire Resistance ◽  
Mechanical Response ◽  
Concrete Strength ◽  
Reinforced Concrete Column ◽  
Rc Columns ◽  
Nonlinear Structural Analysis ◽  
Nonlinear Structural

A nonlinear structural analysis is presented for reinforced concrete (RC) columns exposed to fire. The analysis includes two steps: the first step is the calculation of the temperature distribution in concrete members, and the second the determination of the mechanical response due to elevated temperature and applied loading. In the thermal analysis, the effect of moisture is taken into account. The use of the computer program for evaluating the response of a RC column from the initial preloading stage to collapse, due to fire, is illustrated. The validity of the numerical model used in the program is verified by comparing the predictions from the computer program with measured results from full-scale fire resistance tests. The computer program can be used to predict the fire resistance of RC columns for any values of the significant parameters, such as load level, section dimensions, column length, concrete strength, concrete cover, aggregate type and reinforcement ratio.

scholarly journals Structural performance of frames with concrete-filled steel tubular columns and steel beams: Finite element approach

2019 ◽  
Vol 28 ◽  
pp. 2633366X1989459
Author(s):  
Ahmed Dalaf Ahmed ◽  
Esra Mete Güneyisi
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Slenderness Ratio ◽  
Concrete Strength ◽  
Simulation Models ◽  
Steel Tube ◽  
Nonlinear Material ◽  
Steel Beams ◽  
Sectional Area ◽  
Cross Sectional

Composite columns such as concrete-filled steel tube (CFST) were adopted in many building constructions in recent years because of carrying high loading with the ability to resist buckling and small cross-sectional area. The high behavior of the CFST columns is due to the interaction between steel and concrete which called the composite action. This type of composite column without main and tie reinforcements embedded in concrete gives high axial compression strength to resist the external loadings with the economic sectional area. The work presented in this article includes simulation models that tested by other researchers and a parametric study on the performance of frames that connected steel beam by composed columns of circular CFST that subjected to lateral loading. A finite element (FE) approach is adopted to simulate the models by ANSYS software. All models consider the linear and nonlinear material analysis of the concrete and steel. The validity of the developed model was examined by comparing with the experimental data founded in the literature. Different parameters such as the ratio of the axial load, the slenderness ratio of CFST column, the linear stiffness ratio of the beam–column, the steel yield strength of the beam, the steel yield strength of the tube, and concrete strength on the performance of the composite frames were also studied and the load-deformation performance was obtained over the different cases of the study. Analysis results by FE modeling were in good agreement with the experimental results.

scholarly journals Fire and post-fire performance of circular steel tube confined reinforced concrete columns

2018 ◽  
Author(s):  
Faqi Liu ◽  
Hua Yang ◽  
Sumei Zhang
Keyword(s):  
Reinforced Concrete ◽  
Fire Resistance ◽  
Concrete Columns ◽  
Steel Tube ◽  
Fe Model ◽  
Fire Exposure ◽  
Test Results ◽  
Reinforced Concrete Columns ◽  
Load Bearing ◽  
Circular Steel Tube

Fire and post-fire behaviours of reinforced concrete columns confined by circular steel tubes, also known as circular steel tube confined reinforced concrete (STCRC) columns, are investigated in this paper. 5 full-scale specimens exposed to fire and 47 specimens after fire exposure were tested. Temperatures across the sections, displacement versus time curves, fire resistance, load versus displacement responses and load-bearing capacities were measured and discussed. A finite element (FE) model was developed using the program ABAQUS, and validated against the test results from the present study. Simplified design methods were proposed for predicting the fire resistance and residual load-bearing capacity of the STCRC columns under and after fire exposure, respectively.

scholarly journals Experimental Research on Reinforced Concrete Columns Strengthened with Steel Jacket and Concrete Infill

2021 ◽  
Vol 11 (9) ◽  
pp. 4043
Author(s):  
Aleksandar Landović ◽  
Miroslav Bešević
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Cross Section ◽  
Experimental Research ◽  
Failure Modes ◽  
Steel Tube ◽  
Rc Columns ◽  
Rc Column ◽  
Steel Jacket ◽  
Ductile Behavior

Experimental research on axially compressed columns made from reinforced concrete (RC) and RC columns strengthened with a steel jacket and additional fill concrete is presented in this paper. A premade squared cross-section RC column was placed inside a steel tube, and then the space between the column and the tube was filled with additional concrete. A total of fourteen stub axially compressed columns, including nine strengthened specimens and five plain reinforced concrete specimens, were experimentally tested. The main parameter that was varied in the experiment was the compressive strength of the filler concrete. Three different concrete compression strength classes were used. Test results showed that all three cross-section parts (the core column, the fill, and the steel jacket) worked together in the force-carrying process through all load levels, even if only the basic RC column was loaded. The strengthened columns exhibited pronounced ductile behavior compared to the plain RC columns. The influence of the test parameters on the axial compressive strength was investigated. In addition, the specimen failure modes, strain development, and load vs. deformation relations were registered. The applicability of three different design codes to predict the axial bearing capacity of the strengthened columns was also investigated.

scholarly journals Instability analysis of a filament-wound composite tube subjected to compression/bending

2019 ◽  
Vol 28 ◽  
pp. 096369351987741
Author(s):  
Gyula Szabó ◽  
Károly Váradi
Keyword(s):  
Failure Modes ◽  
Slenderness Ratio ◽  
Equivalent Stress ◽  
Bending Test ◽  
Test Machine ◽  
Fe Model ◽  
Rubber Tube ◽  
Nonlinear Buckling ◽  
Cross Sectional ◽  
Composite Tube

The aim of this study is to investigate the global buckling of a relatively long composite cord–rubber tube subjected to axial compression and its cross-sectional instability due to bending by a macromechanical nonlinear finite element (FE) model (nonlinear buckling analysis). Composite reinforcement layers are modelled as transversely isotropic ones, while elastomer liners are described by a hyperelastic material model that assumes incompressibility. Force–displacement, equivalent strain, equivalent stress results along with oblateness and curvature results for the complete process have been presented. It is justified that bending leads to ovalization of the cross section and results in a loss of the load-carrying capacity of the tube. Strain states in reinforcement layers have been presented, which imply that the probable failure modes of the reinforcement layers are both delamination and yarn-matrix debonding. There is a significant increase in strains due to cross-sectional instability, which proves that the effect of cross-sectional instability on material behaviour of the tube is crucial. A parametric analysis has been performed to investigate the effect of the member slenderness ratio on cross-sectional instability of the composite tube. It shows that Brazier force is inversely proportional to the slenderness ratio. It further shows that higher oblateness parameters occur in case of a lower slenderness ratio and that cross-sectional instability takes place at a lower dimensionless displacement in case of a lower slenderness ratio. FE results have been validated by a compression/bending test experiment conducted on a tensile test machine.

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