Effect of continuous spirals on uni-axial strength and ductility of CFST columns

Concrete-filled steel tube (CFST) columns are increasingly used in the construction of high-rise buildings which require high strength and large working space especially at lower stories. As compared to reinforced concrete columns, existence of the exterior steel tube not only bears a portion of axial load but also most importantly provides confinement to the infill concrete.with the confinement provided by the steel tube, axial strength of the infill concrete can be largely enhanced.this paper presents the investigation effect of impact load on concrete-filled steel tube columns under fire by numerical simulations using ABAQUS software.the results indicate that the CFST sections with larger confinement factor ξ=1.23 behaved in a very ductile manner under lateral impact. And the sections with smaller confinement factor ξ=0.44 generally behaved in a brittle mechanism.

Download Full-text

A numerical model with varying passive confinement for circular and elliptical concrete-filled steel tubular columns

Proceedings 12th international conference on Advances in Steel-Concrete Composite Structures - ASCCS 2018 ◽

10.4995/asccs2018.2018.7246 ◽

2018 ◽

Author(s):

Andrés Lapuebla-Ferri ◽

Cesar Lacuesta ◽

Manuel L. Romero ◽

José M. Adam

Keyword(s):

Numerical Model ◽

Concrete Strength ◽

High Strength ◽

Experimental Tests ◽

Concrete Core ◽

Tubular Columns ◽

Volumetric Deformation ◽

Cfst Columns ◽

Plastic Components ◽

Strength And Ductility

In this work, a non-linear 3D numerical model to study concrete-filled tubular (CFST) columns is presented. The numerical model is capable to consider the passive confinement that occurs in the concrete core of CFST columns, under which an increase in the strength and ductility of the element is expected. Passive confinement is governed by the volumetric deformation of the concrete core and by the increment of concrete strength, so it was necessary to define both aspects in the constitutive model. In the volumetric deformation, the elastic and plastic components were included, the latter by using the Drucker-Prager model. Different values for the angle of dilatancy were defined for normal and high strength concrete. The model was validated by using experimental tests performed on stub columns and eccentrically loaded columns. In addition, different section geometries were tested. According to the results, the model was able to describe the non-uniform confinement that appears in the concrete core of CFST columns.

Download Full-text

Axial load behaviour of steel tube columns in-filled with various high performance concretes

10.32920/ryerson.14654235.v1 ◽

2021 ◽

Author(s):

Katie Chu

Keyword(s):

Axial Load ◽

High Performance ◽

Failure Modes ◽

Lightweight Concrete ◽

High Strength ◽

Crumb Rubber ◽

Steel Tube ◽

Axial Strength ◽

Coarse Aggregates ◽

Cfst Columns

This research concentrates on the axial load behaviour of circular, square and rectangular concrete filled steel tube (CFST) columns incorporating high-performance self-consolidating concretes such as ultra-high strength concrete (UHSC), engineered cementitious composite (ECC), lightweight concrete (LWC), and crumb rubber concrete (CRC). Seventy-four CFST specimens with varying slenderness, shape, concrete type and presence of internal bar reinforcements are tested experimentally under axial compression loading. The effect of these variables on axial load-deformation response, strain characteristics, failure modes, concrete confinement and axial strength are evaluated through experimental results. Performance of existing analytical/code based models for axial strength and concrete confined strength is evaluated. Concretes without coarse aggregates including UHSC proved less effective at enhancing axial strength of filled tube columns through confinement. In contrast, confinement in filled steel tube columns was found most effective with the use of concretes with coarse aggregates such as LWC and CRC.

Download Full-text

Study on Axial Compressive Capacity of FRP-Confined Concrete-Filled Steel Tubes and Its Comparisons with Other Composite Structural Systems

International Journal of Polymer Science ◽

10.1155/2017/6272754 ◽

2017 ◽

Vol 2017 ◽

pp. 1-7 ◽

Cited By ~ 3

Author(s):

Jun Deng ◽

Yifeng Zheng ◽

Yi Wang ◽

Tonghua Liu ◽

Hui Li

Keyword(s):

Basalt Fiber ◽

Fiber Reinforced Polymer ◽

Structural Systems ◽

Fiber Reinforced ◽

Steel Tubes ◽

Axial Strength ◽

Cfrp Sheets ◽

Existing Structures ◽

Reinforced Polymer ◽

Cfst Columns

Concrete-filled steel tubular (CFST) columns have been widely used for constructions in recent decades because of their high axial strength. In CFSTs, however, steel tubes are susceptible to degradation due to corrosion, which results in the decrease of axial strength of CFSTs. To further improve the axial strength of CFST columns, carbon fiber reinforced polymer (CFRP) sheets and basalt fiber reinforced polymer (BFRP) sheets are applied to warp the CFSTs. This paper presents an experimental study on the axial compressive capacity of CFRP-confined CFSTs and BFRP-confined CFSTs, which verified the analytical model with considering the effect of concrete self-stressing. CFSTs wrapped with FRP exhibited a higher ductile behavior. Wrapping with CFRP and BFRP improves the axial compressive capacity of CFSTs by 61.4% and 17.7%, respectively. Compared with the previous composite structural systems of concrete-filled FRP tubes (CFFTs) and double-skin tubular columns (DSTCs), FRP-confined CFSTs were convenient in reinforcing existing structures because of softness of the FRP sheets. Moreover, axial compressive capacity of CFSTs wrapped with CFRP sheets was higher than CFFTs and DSTCs, while the compressive strength of DSTCs was higher than the retrofitted CFSTs.

Download Full-text

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

Canadian Journal of Civil Engineering ◽

10.1139/l11-030 ◽

2011 ◽

Vol 38 (6) ◽

pp. 627-637 ◽

Cited By ~ 10

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%.

Download Full-text

Effect of concrete wet packing density on the uni‐axial strength of manufactured sand CFST columns

Structural Concrete ◽

10.1002/suco.202100280 ◽

2022 ◽

Author(s):

Mianheng Lai ◽

Kaijie Wu ◽

Xiaoling Ou ◽

Mengru Zeng ◽

Chengwei Li ◽

...

Keyword(s):

Packing Density ◽

Manufactured Sand ◽

Axial Strength ◽

Cfst Columns

Download Full-text

Axial strength and ductility of square composite columns with two interlocking spirals

Journal of Constructional Steel Research ◽

10.1016/j.jcsr.2013.07.021 ◽

2013 ◽

Vol 90 ◽

pp. 184-192 ◽

Cited By ~ 8

Author(s):

Tsu-Han Shih ◽

Cheng-Chih Chen ◽

Cheng-Chiang Weng ◽

Samuel Yen-Liang Yin ◽

Jui-Chen Wang

Keyword(s):

Composite Columns ◽

Axial Strength ◽

Interlocking Spirals ◽

Strength And Ductility

Download Full-text

Comparison of the predictability of the ultimate axial strength of elliptical CFST columns using existing square and circular section-based code formulae

Harran Üniversitesi Mühendislik Dergisi ◽

10.46578/humder.875260 ◽

2021 ◽

Author(s):

Süleyman İPEK ◽

Esra Mete GÜNEYİSİ

Keyword(s):

Circular Section ◽

Axial Strength ◽

Cfst Columns

Download Full-text

Comparison of ultimate strength results from ACI and Eurocode 4 for steel tubular columns filled with SCC

MATEC Web of Conferences ◽

10.1051/matecconf/201816204002 ◽

2018 ◽

Vol 162 ◽

pp. 04002

Author(s):

Asraa Al-Goody ◽

Esra Mete Güneyisi ◽

Süleyman İpek

Keyword(s):

American Concrete Institute ◽

Steel Tube ◽

Steel Tubes ◽

Composite Columns ◽

Axial Strength ◽

Tubular Columns ◽

Circular Steel Tube ◽

Structural Applications ◽

Cfst Columns ◽

Infill Material

The Concrete Filled Steel Tubular (CFST) columns have several benefits in comparison to the ordinary steel or reinforced concrete ones. Therefore, they have become more commonly acknowledged in the structural applications. In this study, two design codes such as American Concrete Institute (ACI) and Eurocode 4 (EC4) were used for predicting the ultimate axial strength of CFST columns filled with self-compacting concrete (SCC). To evaluate the results, circular steel tube with different diameter to thickness (D/t) ratio of 30, 60, and 90 and steel yielding strength of 185, 275, and 450 MPa were considered as prediction parameters. The wall thickness and length to diameter (L/D) ratio of the steel tubes were kept constant. As an infill material for the steel tubes, 16 different SCC mixtures reported in the literature were studied and their compressive strength results were used to get the code predicted ultimate axial strength of the composite columns. The analysis of the results based on ACI and EC4 were performed and discussed comparatively.

Download Full-text