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.

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.

Experiment Study on Cyclic Behavior of Concrete Filled Steel Tube (CFST) Column-Reinforced Concrete (RC) Beam Connections

2009 ◽  
Vol 417-418 ◽  
pp. 833-836 ◽  
Author(s):  
Qing Xiang Wang ◽  
Shi Run Liu
Keyword(s):  
Reinforced Concrete ◽  
Tube Wall ◽  
Plastic Hinge ◽  
Steel Tube ◽  
Reinforced Concrete Beams ◽  
Cyclic Behavior ◽  
Concrete Core ◽  
Concrete Filled Steel Tube ◽  
Steel Bars ◽  
Moment Resisting

The test results of six connections under cyclic loading are presented in the paper. Each test specimen was properly designed to model the interior joint of a moment resisting frame, and was identically comprised of three parts that including the circular concrete filled steel tube columns, the reinforced concrete beams, and the short fabricated connection stubs. Energy dissipation was designed to occur in the beams during a severe earthquake. Steel bars which were embedded into concrete core and welded to the connection stubs, were used to transfer the force distributed by the reinforcing bars of concrete beam to the concrete core. The results indicated that the embedded steel bars were very efficient in eliminating the stress concentration on the tube wall and there was no visible deformation occurred on the tube wall until the collapse of the specimen. Furthermore, the connection of each specimen had enough capacity and thus the plastic hinge appeared in the beams. As results, the ductility of this new type structure directly depended on the RC beams.

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 Strength and Deformability of the Concrete Core of Precompressed Concrete Filled Steel Tube Columns of Annular Cross-Section

2019 ◽  
Vol 278 ◽  
pp. 03002
Author(s):  
Anatoly Krishan ◽  
Mariia Astafeva
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Structural Features ◽  
Steel Tube ◽  
Ultimate Strain ◽  
Deformation Model ◽  
Actual Behavior ◽  
Deformation Diagram ◽  
Concrete Core ◽  
Concrete Filled Steel Tube

The advantages of short concrete filled steel tube columns with a precompressed concrete core are presented in the article. Particular cases, where such compression is most appropriate, are listed. Taking into consideration the structural features of concrete filled steel tube columns it is recommended to calculate their bearing capacity on the basis of deformation model of reinforced concrete. The reliability of this calculation will be largely dependent on the conformity of the accepted diagram of the concrete core deformation with its actual behavior. Formulas for determining the strength of precompressed concrete core and the ultimate strain of its shortening are proposed, which allow constructing the sufficiently accurate deformation diagram.

Modelling and Analysis of the Bottom Frames of Multi-Story Masonry Buildings Exposed to Fire

2011 ◽  
Vol 255-260 ◽  
pp. 704-708
Author(s):  
Kai Yan ◽  
Wen Zhong Zheng ◽  
Ying Wang
Keyword(s):  
Reinforced Concrete ◽  
Fire Resistance ◽  
Plastic Material ◽  
Yield Criterion ◽  
Load Ratio ◽  
Material Model ◽  
Masonry Buildings ◽  
Concrete Frames ◽  
Fire Load ◽  
Load Effect

The multi-story masonry buildings with reinforced concrete frames on ground floors collapse more easily than pure frames when bottom frames exposed to fire, for reasons that fire load of its ground floors is relatively large, and the ratio of dead load to the total loads is also large, deformations of joists caused by fire produce adverse effect on arch mechanism of masonry. For the purpose of loading temperature on steel bars and concrete for fire resistance analysis of reinforced concrete structures in ABAQUS, separated loading method is proposed firstly in this article. The Hill yield criterion for compression and the Rankine yield criterion for tension are adopted to establish anisotropic elasto-plastic material model for masonry. The process simulation from temperature rises to buildings collapse is realized. A parametric study is conducted to investigate the effects on fire resistance of the bottom frames when the bottom floors exposed to fire due to the change in effective load ratio, section size and reinforcement ratio. The study shows that the failure mode of the bottom frames exposed to fire is mainly due to columns collapse. Bottom fames designed with seismic class I and II have relatively more safety storage than non-seismic designed bottom frames to resist the fire load effect, and they can satisfy time limits of fire resistance.

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 Post-fire resistance of concrete filled steel tube columns

2020 ◽  
Vol 988 ◽  
pp. 012036
Author(s):  
Ihssan A Alhatmey ◽  
Talha Ekmekyapar ◽  
Nadheer S Ayoob
Keyword(s):  
Fire Resistance ◽  
Steel Tube ◽  
Concrete Filled Steel Tube

Research on seismic behavior of special-shaped CFST column to H-section steel beam joint

2021 ◽  
pp. 136943322110073
Author(s):  
Yu Cheng ◽  
Yuanlong Yang ◽  
Binyang Li ◽  
Jiepeng Liu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Seismic Behavior ◽  
Failure Modes ◽  
Joint Stiffness ◽  
Load Ratio ◽  
Element Model ◽  
Steel Tube ◽  
Steel Beam ◽  
Static Test

To investigate the seismic behavior of joint between special-shaped concrete-filled steel tubular (CFST) column and H-section steel beam, a pseudo-static test was carried out on five specimens with scale ratio of 1:2. The investigated factors include stiffening types of steel tube (multi-cell and tensile bar) and connection types (exterior diaphragm and vertical rib). The failure modes, hysteresis curves, skeleton curves, stress distribution, and joint shear deformation of specimens were analyzed to investigate the seismic behaviors of joints. The test results showed the connections of exterior diaphragm and vertical rib have good seismic behavior and can be identified as rigid joint in the frames with bracing system according to Eurocode 3. The joint of special-shaped column with tensile bars have better seismic performance by using through vertical rib connection. Furthermore, a finite element model was established and a parametric analysis with the finite element model was conducted to investigate the influences of following parameters on the joint stiffness: width-to-thickness ratio of column steel tube, beam-to-column linear stiffness ratio, vertical rib dimensions, and axial load ratio of column. Lastly, preliminary design suggestions were proposed.

Three Types of Stress-Strain Relationship’s Comparison of Circular Tubed Reinforced Concrete in FEA

2012 ◽  
Vol 204-208 ◽  
pp. 930-933
Author(s):  
Xiao Hu ◽  
Zhen Lin Chen
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Uniaxial Stress ◽  
Steel Tube ◽  
Finite Element Analyses ◽  
Stress Strain ◽  
Concrete Filled Steel Tube ◽  
Bearing Analysis

The paper introduces 3 types of uniaxial stress-strain relationships of concrete filled steel tube by Pan Youguang, Susantha and Saenz, and performs finite element analyses of the axial strengths of 18 CTRC columns, studies the characters of three models, and comprises between the axial strengths from FEA and existed experiments. Results show these 3 types of model are all suitable for bearing analysis, but Pan’s model is more accurate.

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