• Title/Summary/Keyword: concrete filled steel tubular column

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An Experimental Study on Structural Performance of Welded Built-up Square CFT Stub Columns (용접조립 각형 CFT 단주의 구조특성에 관한 실험적 연구)

  • Lee, Seong Hui;Choi, Young Hwan;Yom, Kyong Soo;Kim, Jin Ho;Choi, Sung Mo
    • Journal of Korean Society of Steel Construction
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    • v.20 no.5
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    • pp.645-653
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    • 2008
  • Welded built-up square tubes are manufactured by flare welding at the center of the column width for cold-formed L-shaped four-piece plates and improved composite effect of concrete and steel by vertical inner anchor. Also, the axial resistance of concrete is increased by the thinness of the steel column, and the composite effect of concrete and steel prevents the steel column from local buckling. In this study, we introduced a manufacturing method of built-up square column steel square concrete-filled tubular column with vertical inner anchor and superior structural performance of the square stub column verified by the structural test for 15 specimens with parameters of shape of tube (built-up square tube, general steel tube), width over thickness of the steel tube (B/t=50, 58, 67) and the strength of concrete (f'c=10MPa, 50MPa).

Second-order inelastic dynamic analysis of cable-stayed bridges using rectangular concrete-filled steel tubular columns

  • Van-Tuong Bui;Seung-Eock Kim
    • Steel and Composite Structures
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    • v.52 no.6
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    • pp.673-693
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    • 2024
  • An advanced numerical method is proposed in this paper for the second-order inelastic dynamic analysis of cable-stayed bridges using rectangular concrete-filled steel tubular (CFST) columns under earthquake loadings for the first time. The proposed method can exactly predict the nonlinear response of the bridges by using only one element per member in simulating the structural model. This comes from considering both the geometric and material nonlinearities in a fiber beam-column element and a catenary cable element. In the fiber beam-column element, the geometric nonlinearities are captured by applying the stability functions, whereas the material nonlinearities are evaluated by tracing the uniaxial cyclic stress-strain curves of each fiber on the cross-sections, which are located at the integration points along the member length. A computer program was developed based on Newmark's average acceleration algorithm to solve the nonlinear equations of motion. The accuracy and computational efficiency of the proposed program were verified by comparing the predicted results with the experimental results, and the results obtained from the commercial software SAP2000 and ABAQUS. The proposed program is promising as a useful tool for practical designs for the nonlinear inelastic dynamic analysis of cable-stayed bridges.

A new base plate system using deformed reinforcing bars for concrete filled tubular column

  • Park, Yong-Myung;Hwang, Won-Sup;Yoon, Tae-Yang;Hwang, Min-Oh
    • Steel and Composite Structures
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    • v.5 no.5
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    • pp.375-394
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    • 2005
  • An experimental study was conducted to develop a new base plate anchorage system for concrete filled tubular column under an axial load and a moment. The column was connected to a concrete foundation using ordinary deformed reinforcing bars that are installed at the inside and outside of the column. In order to investigate the moment resisting capacity of the system, horizontal cyclic loads are applied until the ultimate condition is reached with the axial load held constant. To derive a design method for moment resisting capacity, the reinforced concrete section approach was investigated with the assumption of strain compatibility. The results by this approach agreeded well with those of experiments when the bearing pressure of confined concrete and tangent modulus of steel bars are assumed appropriately. Also, it was found that the column interaction curve can be used to predict the yield strength of the base plate system.

Experimental Study on the Structural Behavior of Concrete-Filled Circular Tubular Column to H-Beam connections without Diaphragm (다이아프램이 없는 콘크리트 충전 원형강관 기둥-H형강 보 접합부의 구조적 거동에 관한 실험적 연구)

  • Kang, Hyun Sik;Moon, Tae Sup
    • Journal of Korean Society of Steel Construction
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    • v.9 no.1 s.30
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    • pp.13-22
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    • 1997
  • This paper is concerned with an experimental study on structural behavior of Concrete-Filled Circular Tubular(CFCT) column to H-beam connections. The important parameters are the number of inner reinforced rib and the width of H-beam flange(100, 150, 200mm) with variable column thickness(5.8mm, 9.2mm, 12.5mm) around the joint between CFCT and H-beam. Test results are summarized for the displacement, strength, initial stiffness, failure mode and energy absorption capacity of each specimen. The purpose of this paper is to investigate the initial stiffness and the strength of connections to evaluate the structural behavior of the CFCT column to H-beam connections. From the discussion about the test results, the basic data for non diaphragm connection design would be suggested.

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Buckling resistance of axially loaded square concrete-filled double steel tubular columns

  • Ci, Junchang;Ahmed, Mizan;Tran, Viet-Linh;Jia, Hong;Chen, Shicai;Nguyen, Tan N.
    • Steel and Composite Structures
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    • v.43 no.6
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    • pp.689-706
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    • 2022
  • Thin-walled square concrete-filled double steel tubular (CFDST) columns composed of the inner circular tube filled with concrete can be used to carry the large axial loads or strengthen existing CFST columns in composite constructions. This paper reports an experimental program carried out on short square CFDST columns loaded concentrically. The influences of important column parameters on the post-buckling performance of such columns are investigated. Test results exhibit that the inner circular tube significantly improves the ultimate loads and the ductility of such columns compared to conventional concrete-filled steel tubular (CFST) and double-skin CFST (DCFST) columns with an inner void. A mathematical model developed is used to simulate the ultimate strengths and load-strain curves of such columns loaded axially. Furthermore, the ultimate strengths of such columns are predicted using existing codified design models for conventional CFST columns as well as the formulas proposed by previous researchers and compared against a large database comprising 500 CFDST columns. Lastly, an accurate artificial neural network model is developed for the practical applications of such columns under axial loading.

Strength of Square Shaped CFT Stub Column Considering the Confining Effect of Concrete (콘크리트 구속효과를 고려한 정사각형 CFT단주의 강도)

  • Hwang, Won Sup;Kim, Dong Jo
    • Journal of Korean Society of Steel Construction
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    • v.14 no.6
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    • pp.813-822
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    • 2002
  • The squash strength and design strength are smaller than the experimental strength of square shaped concrete-filled steel tubular columns in a short concentrically loaded column. This study presents an evaluation procedure accounting for the confining effect of concrete. For the purpose of evaluating a confining effect of concrete, the 3D finite element method was used. The influence of parameters, width-thickness ratios, strength of the concrete and the yield strength of the steel, were examined. The suggested evaluation procedure that assembled three parameters was compared with previous experimental results. Also, the tendency of the confining effect of concrete was examined in the three types of load application.

Resistance and Flexure Behavior of Slender Welded Built-up Square CFT Column Using Internal Reinforced Steel Tube under Eccentric Loads (강관내부 보강재를 고려한 용접조립 각형 CFT 편심 장주의 내력 및 휨 거동)

  • Lee, Seong-Hui;Kim, Young-Ho;Choi, Sung-Mo
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.6 no.2
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    • pp.32-39
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    • 2015
  • So far, square concrete filled tubular(CFT) columns have been used in a limited width thickness ratio. The reason is that local buckling occurs in steel tube easily. Once the local buckling occurs, the confinement effect of steel tube on concrete disappears. In this study, we developed welded built-up square steel tube with reinforcement which are placed at the center of the tube width acts as an anchor. 3 specimens of slender welded built-up square CFT columns and 3 specimens of slender welded built-up square steel tube columns were manufactured with parameters of width(B) of steel tube, width thickness ratio(B/t). we conducted a experimental test on the 6 specimens under eccentric load, and evaluated the structural resistance and behavior of 6 specimens.

Compressive Behaviour of Geopolymer Concrete-Filled Steel Columns at Ambient and Elevated Temperatures

  • Tao, Zhong;Cao, Yi-Fang;Pan, Zhu;Hassan, Md Kamrul
    • International Journal of High-Rise Buildings
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    • v.7 no.4
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    • pp.327-342
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    • 2018
  • Geopolymer concrete (GPC), which is recognised as an environmentally friendly alternative to ordinary Portland cement (OPC) concrete, has been reported to possess high fire resistance. However, very limited research has been conducted to investigate the behaviour of geopolymer concrete-filled steel tubular (GCFST) columns at either ambient or elevated temperatures. This paper presents the compressive test results of a total of 15 circular concrete-filled steel tubular (CFST) stub columns, including 5 specimens tested at room temperature, 5 specimens tested at elevated temperatures and the remaining 5 specimens tested for residual strength after exposure to elevated temperatures. The main variables in the test program include: (a) concrete type; (b) concrete strength; and (c) curing condition of geopolymer concrete. The test results demonstrate that GCFST columns have similar ambient temperature behaviour compared with the conventional CFST counterparts. However, GCFST columns exhibit better fire resistance than the conventional CFST columns. Meanwhile, it is found that the GCFST column made with heat cured GPC has lower strength loss than other columns after exposure to elevated temperatures. The research results highlight the possibility of using geopolymer concrete to improve the fire resistance of CFST columns.

Axial compression behavior of double-skinned composite tubular columns under pure compression on concrete cores

  • Lee, Jeonghwa;Byun, Namju;Kang, Young Jong;Won, Deok Hee;Kim, Seungjun
    • Steel and Composite Structures
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    • v.43 no.4
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    • pp.431-445
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    • 2022
  • A double-skinned composite tubular (DSCT) column, which is an internally confined concrete-filled tubular column with a hollow section, has been developed for efficient use of materials that reduce self-weight and enhance seismic performance. It exhibits excellent material behavior with ductility owing to the confinement induced by outer and inner steel tubes. This study conducted axial compression tests considering the effects of steel tube thickness and hollow diameter ratios of DSCT columns on the material behavior of confined concrete under pure axial compression on concrete cores. From the axial compression tests, various combinations of outer and inner tube thicknesses and two different hollow section ratios were considered. Additionally, confined concrete material behavior, axial strength, failure modes, and ductility of DSCT columns were evaluated. Based on this study, it was concluded that the tests show a good correlation with peak strength and shapes of nonlinear stress-strain curves presented in literature; however, the thinner outer and inner steel tubes may reduce the ductility of DSCT columns when using thinner outer and inner tubes and higher confined stress levels. Finally, the minimum thickness requirements of the steel tubes for DSCT columns were discussed in terms of strength and ductility of test specimens.

Design of High Strength Concrete Filled Tubular Columns For Tall Buildings

  • Liew, J.Y. Richard;Xiong, M.X.;Xiong, D.X.
    • International Journal of High-Rise Buildings
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    • v.3 no.3
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    • pp.215-221
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    • 2014
  • Ultra-high strength concrete and high tensile steel are becoming very attractive materials for high-rise buildings because of the need to reduce member size and structural self-weight. However, limited test data and design guidelines are available to support the applications of high strength materials for building constructions. This paper presents significant findings from comprehensive experimental investigations on the behaviour of tubular columns in-filled with ultra-high strength concrete at ambient and elevated temperatures. A series of tests was conducted to investigate the basic mechanical properties of the high strength materials, and structural behaviour of stub columns under concentric compression, beams under moment and slender beam-columns under concentric and eccentric compression. High tensile steel with yield strength up to 780 MPa and ultra-high strength concrete with compressive cylinder strength up to 180 MPa were used to construct the test specimens. The test results were compared with the predictions using a modified Eurocode 4 approach. In addition, more than 2000 test data samples collected from literature on concrete filled steel tubes with normal and high strength materials were also analysed to formulate the design guide for implementation in practice.