Bond strength in concrete filled built-up steel tube columns with tab stiffeners

2011 ◽  
Vol 38 (6) ◽  
pp. 627-637 ◽  
Author(s):  
Clotilda Petrus ◽  
Hanizah Abdul Hamid ◽  
Azmi Ibrahim ◽  
Joe Davylyn Nyuin
Keyword(s):  
Experimental Investigation ◽  
Bond Strength ◽  
Mild Steel ◽  
Steel Tube ◽  
Composite Action ◽  
Strength Concrete ◽  
Cfst Columns ◽  
Push Out ◽  
Strength And Ductility ◽  
Concrete Cube

Apart from strength and ductility, adequate bond between steel and concrete at the interface is important in concrete filled steel tube (CFST) columns to ensure a composite action. One way of improving the bond strength of a CFST column is introducing internal stiffeners. This paper presents an experimental investigation into the bond strength of a CFST column with tab stiffeners by conducting a push out test. Twenty-one square specimens of sides 200 mm × 200 mm, fabricated from 2 mm thick mild steel sheeting were tested in two series. The first series considered the variation in the tab spacing along the stiffeners, namely 75, 100, 150, and 300 mm, while in the second series, the concrete cube compressive strengths were 36, 40, and 50 MPa. The bond strength at the concrete–steel interface was found to increase with decreasing tab spacing. In-filling the tubes with higher strength concrete had also resulted in an increase in the bond strength by up to an average of 40%.

Push-out tests and bond strength of rectangular CFST columns

2015 ◽  
Vol 19 (1) ◽  
pp. 21-41 ◽  
Author(s):  
Xiushu Qu ◽  
Zhihua Chen ◽  
David A. Nethercot ◽  
Leroy Gardner ◽  
Marios Theofanous
Keyword(s):  
Bond Strength ◽  
Cfst Columns ◽  
Push Out

scholarly journals Interfacial Bond Behavior of High Strength Concrete Filled Steel Tube after Exposure to Elevated Temperatures and Cooled by Fire Hydrant

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 150
Author(s):  
Zongping Chen ◽  
Jiyu Tang ◽  
Xingyu Zhou ◽  
Ji Zhou ◽  
Jianjia Chen
Keyword(s):  
Bond Strength ◽  
High Strength Concrete ◽  
Elevated Temperatures ◽  
High Strength ◽  
Steel Tube ◽  
Water Cooling ◽  
Interfacial Bond ◽  
Concrete Filled Steel Tube ◽  
Bond Behavior ◽  
Strength Concrete

For the engineering structure in case of fire, a fire hydrant is generally used for extinguishing the fire. This paper presents an experimental investigation on interfacial bond behavior of high-strength concrete-filled steel tube (HSCFST) after exposure to elevated temperatures and cooled by fire hydrant using the pull-out test of 22 specimens. According to the experimental study, the failure mechanism of HSCFST exposed to elevated temperatures and water-cooling (ETWC) was revealed, the influence of various parameters on the bond behavior was analyzed, and the calculation formula of the bond strength of HSCFST subjected to ETWC was put forward. The results show that the load-slip curves of the loading end and the free end of the specimen are basically similar, and can be divided into three types of typical curves. In the push out test, the strain on the outer surface of the steel tube is exponentially distributed with its distance from the loading end. After ETWC exposure, the bond strength of the specimen is less affected by the concrete strength, which is inversely proportional to the anchorage length, and it is basically stable after the constant temperature duration is longer than 60 min. With the increase of the maximum temperature, the ultimate bond strength increases first, then decreases and then increases, and the residual bond strength increases first and then decreases. Besides, the study indicate that cooling method has significant influence on the bond behavior, compared with natural cooling specimens, the ultimate bond strength, residual bond strength, and shear bond stiffness of water-cooling specimens are smaller, and the interfacial energy dissipation capacity is larger.

scholarly journals Experimental Behaviour of Steel Tubular Columns for Varying in Filled Concrete

2017 ◽  
Vol 63 (4) ◽  
pp. 149-160 ◽  
Author(s):  
P. Sangeetha ◽  
R. Senthil
Keyword(s):  
Carrying Capacity ◽  
Slenderness Ratio ◽  
Steel Tube ◽  
Load Carrying Capacity ◽  
Concrete Core ◽  
Composite Action ◽  
Tubular Columns ◽  
Load Carrying ◽  
Cfst Columns ◽  
Quarry Dust

AbstractThis paper investigates the behaviour of axially-loaded tubular columns filled with M20 grade concrete and partially replaced concrete. The parameters varying in the study are slenderness ratio (13.27, 16.58 & 19.9), and normal M20 grade concrete, partially replaced quarry dust and concrete debris. The effects of the various concrete mixes and composite action between the steel tube and the concrete core are studied and a graph visualizing the differences between the load carrying capacity and the axial deflection is plotted. Some of the performance indices like the Ductility Index (DI), Concrete Contribution Ratio (CCR), Confinement Index (θ) and Strength Index (SI) are also evaluated and compared amongst the CFST columns. From the results it has been noted that an increase in the L/D ratio decrease the behaviour of the composite columns irrespective of the in filled materials. The composite action was achieved in the CFST columns filled with partially replaced quarry dust and concrete debris when compared with hollow steel columns. The load carrying capacity of the CFST column increases by 32 % compared with the hollow tubular columns.

scholarly journals Finite Model Analysis and Practical Design Equations of Circular Concrete-Filled Steel Tube Columns Subjected to Compression-Torsion Load

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5564
Author(s):  
Yongzhi Gong ◽  
Faxing Ding ◽  
Liping Wang ◽  
Borong Huang ◽  
Yingjie Shan ◽  
...  
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Axial Force ◽  
Maximum Shear Stress ◽  
Steel Tube ◽  
Steel Tubes ◽  
Concrete Filled Steel Tube ◽  
Composite Action ◽  
Practical Design ◽  
Cfst Columns

The objective of this study is to investigate the mechanical properties and the composite action of circular concrete-filled steel tube (CFST) columns subjected to compression-torsion load using finite element model analysis. Load–strain (T–γ) curves, normal stress, shear stress, and the composite action between the steel tubes and the interior concrete were analyzed based on the verified 3D finite element models. The results indicate that with the increase of axial force, the maximum shear stress at the core concrete increased significantly, and the maximum shear stress of the steel tubes gradually decreased. Meanwhile, the torsional bearing capacity of the column increased at first and then decreased. The torque share in the columns changed from the tube-sharing domain to the concrete-sharing domain, while the axial force of the steel tube remained unchanged. Practical design equations for the torsional capacity of axially loaded circular CFST columns were proposed based on the parametric analysis. The accuracy and validity of the proposed equations were verified against the collected experimental results.

scholarly journals Influence of steel tube thickness and concrete strength on the axial capacity of stub CFST columns

2018 ◽  
Author(s):  
Carmen Ibáñez Usach ◽  
David Hernández-Figueirido ◽  
Ana Piquer Vicent
Keyword(s):  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Steel Tube ◽  
Experimental Program ◽  
Ultimate Capacity ◽  
Strength Concrete ◽  
Axial Capacity ◽  
Thin Walled ◽  
Cfst Columns

In order to study the mechanical response of concrete-filled steel tubular (CFST) columns, several experimental and theoretical studies have been conducted in the last years. However, the influence of thin-walled steel tubes on the axial capacity of these composite columns is not completely stablished, especially when it is combined with high-strength concrete as infill. In this paper, the results of an experimental campaign on 9 concrete-filled steel tubular stub columns subjected to concentric load are presented. Different cross-section shapes are considered in this campaign, i.e. circular, square and rectangular. The influence of the steel tube wall thickness is analysed by including in the tests specimens with thin-walled tubes, whose behaviour needs to be studied in depth given the issues arising when working under compression. The experimental program is designed so the analysis of the results permits to drawn consistent conclusions. For each series, the steel tube thickness is the only geometric parameter modified in order to properly study its effect. Besides, two different concrete strengths were considered for the concrete infill, i.e. normal and high- strength concrete, to observe their effect on the ultimate capacity of the columns. During the tests, the specimens are subjected to axial load and the evolution of the axial displacement with the load is registered. The ultimate capacity of each specimen is obtained and an analysis of the steel tube thickness and concrete strength influence is accomplished. Finally, the study of the dependency of the failure mode on these parameters is carried out.

scholarly journals Use of the Gene-Expression Programming Equation and FEM for the High-Strength CFST Columns

2021 ◽  
Vol 11 (21) ◽  
pp. 10468
Author(s):  
Huanjun Jiang ◽  
Ahmed Salih Mohammed ◽  
Reza Andasht Kazeroon ◽  
Payam Sarir
Keyword(s):  
Gene Expression ◽  
Bearing Capacity ◽  
High Strength Concrete ◽  
Gene Expression Programming ◽  
High Strength ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Quick Method ◽  
Strength Concrete ◽  
Cfst Columns

The ultimate strength of composite columns is a significant factor for engineers and, therefore, finding a trustworthy and quick method to predict it with a good accuracy is very important. In the previous studies, the gene expression programming (GEP), as a new methodology, was trained and tested for a number of concrete-filled steel tube (CFST) samples and a GEP-based equation was proposed to estimate the ultimate bearing capacity of the CFST columns. In this study, however, the equation is considered to be validated for its results, and to ensure it is clearly capable of predicting the ultimate bearing capacity of the columns with high-strength concrete. Therefore, 32 samples with high-strength concrete were considered and they were modelled using the finite element method (FEM). The ultimate bearing capacity was obtained by FEM, and was compared with the results achieved from the GEP equation, and both were compared to the respective experimental results. It was evident from the results that the majority of values obtained from GEP were closer to the real experimental data than those obtained from FEM. This demonstrates the accuracy of the predictive equation obtained from GEP for these types of CFST column.

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