Overview of Research Progress for Concrete-Filled Steel Tubular Columns after Exposure to Fire

2014 ◽  
Vol 638-640 ◽  
pp. 197-201
Author(s):  
Yan Chong Pan ◽  
Guo Hui Wang ◽  
Kai Xiang
Keyword(s):  
Mechanical Properties ◽  
Residual Strength ◽  
Fire Safety ◽  
Axial Load ◽  
Research Progress ◽  
Building Structures ◽  
Fire Exposure ◽  
Tubular Columns ◽  
Cfst Columns ◽  
Exposure Process

Fire safety is one of the most important performances index to evaluate building structures. The property of building members after exposure to fire involved with the safety of buildings after fire, and it will be necessary to estimate the post-fire residual strength of the structure in order to decide the appropriate strategy for repair. This paper summarizes the research progress of concrete-filled steel tubular (CFST) columns. Basic mechanical properties of conventional CFST columns after exposure to fire, CFST columns after the whole fire exposure process under sustained axial load, and CFST columns with special forms after exposure to fire are discussed.

Review of Fire Performance Experiment of Concrete-Filled Steel Tubular Columns

2014 ◽  
Vol 638-640 ◽  
pp. 1397-1401
Author(s):  
Kai Xiang ◽  
Guo Hui Wang ◽  
Yan Chong Pan
Keyword(s):  
Load Ratio ◽  
Experimental Results ◽  
Research Progress ◽  
Future Research ◽  
Fire Performance ◽  
Cross Sectional ◽  
Tubular Columns ◽  
Cross Sectional Dimension ◽  
Cfst Columns ◽  
In Fire

This paper presents a review of research progress in fire performance of concrete-filled steel tubular (CFST) columns. Experimental results of CFST columns in fire are reviewed with influence parameters, such as heights, cross-sectional dimension, section types, concrete types, concrete strengths, load ratio, load eccentricity, fire exposed sides and so on. Some conclusions of CFST columns under fire conditions are summarized. Deficiencies in the fire performance experiments of CFST columns are identified, which provide the focus for future research in the field.

Experimental Investigation of Stiffened Square CFST Columns under Axial Load

2014 ◽  
Vol 919-921 ◽  
pp. 1794-1800
Author(s):  
Xin Zhi Zheng ◽  
Xin Hua Zheng
Keyword(s):  
Experimental Investigation ◽  
Bearing Capacity ◽  
Cross Sections ◽  
Axial Load ◽  
Local Buckling ◽  
Test Results ◽  
Tubular Columns ◽  
Economical Benefit ◽  
Steel Consumption ◽  
Cfst Columns

Abstract: 7 square steel tubular columns were tested to discuss the ultimate axial bearing capacity, ductility performance and the steel consumption under stiffened by steel belts and binding bars of different cross-sections. Test results indicate that only by increasing fewer amounts of steel usage, stiffened square CFST columns with binding bars can not only improve the overall effects of restraint and alleviate regional local buckling between the binding bars, but also improve the bearing capacity of concrete filled square steel tubular columns. The utility benefits and the economical benefit is considerable, deserving extensive use.

scholarly journals Fire-resistance Rating of Square Steel Tubes and Concrete-filled Square Steel Tubular Columns Protected with Ultra-thin Fire-retardant Coating

2020 ◽  
Vol 71 (6) ◽  
pp. 437-451
Author(s):  
Ansheng Wu ◽  
Bo Zhang ◽  
Le Tian
Keyword(s):  
Test Specimen ◽  
Fire Retardant ◽  
Building Structures ◽  
Fire Exposure ◽  
Test Results ◽  
Steel Tubes ◽  
Tubular Columns ◽  
Variation Characteristics ◽  
Test Furnace ◽  
Fireproof Coating

To promote and criterionize the application of ultra-thin the fireproof coating s to building structures, four concrete-filled square steel tubular (CFSST) pillars as well as two square steel tubes, each protected along with ultra-thin the fireproof coating , were subjected to full-scale fire tests to investigate their fireproof level on the basis of the ISO 834 criterion time�degrees curve. Test results revealed not only the temperature variation characteristics of specimens suffered from inconsistent fire exposure, but also effects of the steel ratio of the test specimen and the number of fire-exposed sides on the fire-refractory level of the test specimen. Test results demonstrated that when protected with an ultra-thin the fireproof coating , the heating rate of the specimens was considerably lower than that of the test furnace, suggesting that the ultra-thin the fireproof coating exhibits good thermal insulation performance. The test results were compared with China�s current criterions for the fire-refractory level of square steel tubes and CFSST pillars, indicating that the criterions would lead to a relatively conservative fire-safe design for four-side fire exposure.

EXPERIMENTAL ASSESSMENT OF CONCENTRICALLY LOADED PRE-STRESSING CONCRETE-FILLED STEEL TUBULAR COLUMNS

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Aman Mwafy ◽  
Amr El-Dieb ◽  
Abdulaziz Lazkani
Keyword(s):  
Compressive Strength ◽  
Axial Load ◽  
Load Capacity ◽  
Concrete Compressive Strength ◽  
Tubular Columns ◽  
Modes Of Failure ◽  
Axial Load Capacity ◽  
Load Tests ◽  
Expansive Additive ◽  
Cfst Columns

Although expansive additives are frequently used in contemporary concrete-filled steel tubular (CFST) structures to improve the bond between concrete and steel tubes, little information is available regarding their influence on the mechanical characteristics of CFST columns. This reflects the pressing need to investigate the impacts of the pre-stressing achieved through the expansive additives, especially on the concrete confinement and axial load capacity of CFST. This paper thus discusses the results of concentric load tests carried out for 12 pre-stressing CFST columns to assess their axial load capacity and modes of failure. The main parameters investigated are the concrete compressive strength (40, 50 and 90 MPa) and the dosage of the expansive agent (0%, 6%, 12% and 24% by mass of cement). The results indicate that the axial load capacity is improved by increasing both the concrete compressive strength and the expansive additive dosage. The expansive additive has an important influence on the confinement effect of CFST. The paper presents new test results that contribute to fill a gap in the literature and provides insights into the behavior of concentrically loaded pre-stressing CFST columns.

The Constitutive Relationship of Concrete Core in Circular Concrete-Filled Steel Tubular Columns

2010 ◽  
Vol 163-167 ◽  
pp. 2063-2067
Author(s):  
Lin Lin Liu ◽  
Yong Qing Tu ◽  
Ying Hua Ye
Keyword(s):  
Numerical Simulation ◽  
Axial Load ◽  
Lateral Pressure ◽  
Confined Concrete ◽  
Constitutive Relationship ◽  
Concrete Core ◽  
Tubular Columns ◽  
Cfst Columns ◽  
Relationship Of ◽  
Concrete Model

Considering the confining mechanism in circular concrete-filled steel tubular (CFST) columns, a volume-based method for dividing the effectively and ineffectively confined area of concrete core and calculating the value of effectively confined coefficient is presented. The constitutive relationship of concrete core is developed by means of modifying the expressions of effective lateral pressure and the descending stage in Mander’s confined concrete model. Numerical simulation of several circular CFST columns under axial load is carried out in ABAQUS. The comparisons between calculated results and experimental results demonstrate that the suggested concrete constitutive relationship is appropriate for the nonlinear analysis of circular CFST columns.

Effects of bottom plate in friction stir welding of AA6061-T6

2020 ◽  
Vol 118 (1) ◽  
pp. 108
Author(s):  
M.A. Vinayagamoorthi ◽  
M. Prince ◽  
S. Balasubramanian
Keyword(s):  
Mechanical Properties ◽  
Axial Load ◽  
Weld Zone ◽  
Welding Process ◽  
Bottom Plate ◽  
Welding Parameters ◽  
Nugget Zone ◽  
Friction Stir ◽  
Weld Joints ◽  
Fine Grain

The effects of 40 mm width bottom plates on the microstructural modifications and the mechanical properties of a 6 mm thick FSW AA6061-T6 joint have been investigated. The bottom plates are placed partially at the weld zone to absorb and dissipate heat during the welding process. An axial load of 5 to 7 kN, a rotational speed of 500 rpm, and a welding speed of 50 mm/min are employed as welding parameters. The size of the nugget zone (NZ) and heat-affected zone (HAZ) in the weld joints obtained from AISI 1040 steel bottom plate is more significant than that of weld joints obtained using copper bottom plate due to lower thermal conductivity of steel. Also, the weld joints obtained using copper bottom plate have fine grain microstructure due to the dynamic recrystallization. The friction stir welded joints obtained with copper bottom plate have exhibited higher ductility of 8.9% and higher tensile strength of 172 MPa as compared to the joints obtained using a steel bottom plate.

scholarly journals A Review: Research Progress in Modification of Poly (Lactic Acid) by Lignin and Cellulose

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 776
Author(s):  
Sixiang Zhai ◽  
Qingying Liu ◽  
Yuelong Zhao ◽  
Hui Sun ◽  
Biao Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Composite Materials ◽  
Crystallization Rate ◽  
Research Progress ◽  
Poly Lactic Acid ◽  
Green Composite ◽  
Materials Development ◽  
Research Attention ◽  
Biomass Components

With the depletion of petroleum energy, the possibility of prices of petroleum-based materials increasing, and increased environmental awareness, biodegradable materials as a kind of green alternative have attracted more and more research attention. In this context, poly (lactic acid) has shown a unique combination of properties such as nontoxicity, biodegradability, biocompatibility, and good workability. However, examples of its known drawbacks include poor tensile strength, low elongation at break, poor thermal properties, and low crystallization rate. Lignocellulosic materials such as lignin and cellulose have excellent biodegradability and mechanical properties. Compounding such biomass components with poly (lactic acid) is expected to prepare green composite materials with improved properties of poly (lactic acid). This paper is aimed at summarizing the research progress of modification of poly (lactic acid) with lignin and cellulose made in in recent years, with emphasis on effects of lignin and cellulose on mechanical properties, thermal stability and crystallinity on poly (lactic acid) composite materials. Development of poly (lactic acid) composite materials in this respect is forecasted.

scholarly journals Effect of Elevated Temperature on Mechanical Properties of High-Volume Fly Ash-Based Geopolymer Concrete, Mortar and Paste Cured at Room Temperature

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1473
Author(s):  
Jun Zhao ◽  
Kang Wang ◽  
Shuaibin Wang ◽  
Zike Wang ◽  
Zhaohui Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Residual Strength ◽  
Elevated Temperatures ◽  
High Volume ◽  
Sem Analysis ◽  
Geopolymer Concrete ◽  
Ordinary Concrete ◽  
Exposure Temperature

This paper presents results from experimental work on mechanical properties of geopolymer concrete, mortar and paste prepared using fly ash and blended slag. Compressive strength, splitting tensile strength and flexural strength tests were conducted on large sets of geopolymer and ordinary concrete, mortar and paste after exposure to elevated temperatures. From Thermogravimetric analyzer (TGA), X-ray diffraction (XRD), Scanning electron microscope (SEM) test results, the geopolymer exhibits excellent resistance to elevated temperature. Compressive strengths of C30, C40 and C50 geopolymer concrete, mortar and paste show incremental improvement then followed by a gradual reduction, and finally reach a relatively consistent value with an increase in exposure temperature. The higher slag content in the geopolymer reduces residual strength and the lower exposure temperature corresponding to peak residual strength. Resistance to elevated temperature of C40 geopolymer concrete, mortar and paste is better than that of ordinary concrete, mortar and paste at the same grade. XRD, TGA and SEM analysis suggests that the heat resistance of C–S–H produced using slag is lower than that of sulphoaluminate gel (quartz and mullite, etc.) produced using fly ash. This facilitates degradation of C30, C40 and C50 geopolymer after exposure to elevated temperatures.

scholarly journals Approaches to the Mechanical Properties of Threaded Studs Welded to RHS Columns

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1429
Author(s):  
Ismael García ◽  
Miguel A. Serrano ◽  
Carlos López-Colina ◽  
Fernando L. Gayarre ◽  
Jesús M. Suárez
Keyword(s):  
Mechanical Properties ◽  
Tensile Tests ◽  
Efficient Solutions ◽  
Bolted Joints ◽  
Building Structures ◽  
Static Behavior ◽  
Steel Tubes ◽  
Punch Test ◽  
Different Types ◽  
The Face

The use of Rectangular Hollow Sections (RHS) as columns in steel construction includes important advantages like higher mechanical strength and fire resistance. However, the practical demountable bolted joints between beams and columns are not easy to execute, due to impossibility of access to the inner part of the tube. The use of threaded studs welded to the face of the tube and bolted to the beam by means of angle cleats is one of the cheaper and most efficient solutions to obtain beam–column joints with a semi-rigid behavior, as is usually sought in building structures. Nevertheless, it is important to point out that the stud-diameter and the stud-class selection may affect the mechanical properties of the welded parts of the joint. In this paper, 8MnSi7 (with a commercial designation K800) and 4.8 threaded studs were welded to RHS steel tubes and mechanical properties on the weld, the Heat Affected Zones (HAZ), and the base metal were obtained in two different ways: through a correlation with the Vickers hardness and by means of the Small Punch Test (SPT). A study of the microstructure and tensile tests on the threaded studs and in the columns was also carried out. The research involved different types of stud qualities, tube wall thicknesses, and stud diameters. The work presented in this paper proved that in most cases, the welded joint between these studs and the RHS steel tubes present a reasonable static behavior that fulfils the requirements for the beam–column joints under static loading.

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