• Steel and Composite Structures
• /
• 제1권1호
• /
• pp.51-74
• /
• 2001

A series of tests on concrete-filled SHS (Square Hollow Section) stub columns (twenty), columns (eight) and beam-columns (twenty one) were carried out. The main parameters varied in the tests are (1) Confinement factor (${\xi}$) from 1.08 to 5.64, (2) concrete compression strength from 10.7MPa to 36.6MPa, (3) tube width to thickness ratio from 20.5 to 36.5. (4) load eccentricity (e) from 15 mm to 80 mm and (5) column slenderness (${\lambda}$) from 45 to 75. A mechanics model is developed in this paper for concrete-filled SHS stub columns, columns and beam-columns. A unified theory is described where a confinement factor (${\xi}$) is introduced to describe the composite action between the steel tube and filled concrete. The predicted load versus axial strain relationship is in good agreement with stub column test results. Simplified models are derived for section capacities and modulus in different stages of the composite sections. The predicted beam-column strength is compared with that of 331 beam-column tests with a wide range of parameters. A good agreement is obtained. The predicted load versus midspan deflection relationship for beam-columns is in good agreement with test results. A simplified model is developed for calculating the member capacity of concrete-filled SHS columns. Comparisons are made with predicted columns strengths using the existing codes such as LRFD (AISC 1994), AIJ (1997), and EC4 (1996). Simplified interaction curves are derived for concrete-filled beam-columns.

• Steel and Composite Structures
• /
• 제9권1호
• /
• pp.19-38
• /
• 2009

The present paper provides test data to evaluate the seismic performance of recycled aggregate concrete (RAC) filled steel square hollow section (SHS) beam-columns. Fifteen specimens, including 12 RAC filled steel tubular (RACFST) columns and 3 reference conventional concrete filled steel tubular (CFST) columns, were tested under reversed cyclic flexural loading while subjected to constant axially compressive load. The test parameters include: (1) axial load level (n), from 0.05 to 0.47; and (2) recycled coarse aggregate replacement ratio (r), from 0 to 50%. It was found that, generally, the seismic performance of RACFST columns was similar to that of the reference conventional CFST columns, and RACFST columns exhibited high levels of bearing capacity and ductility. Comparisons are made with predicted RACFST beam-column bearing capacities and flexural stiffness using current design codes. A theoretical model for conventional CFST beam-columns is employed in this paper for square RACFST beam-columns. The predicted load versus deformation hysteretic curves are found to exhibit satisfactory agreement with test results.

• Steel and Composite Structures
• /
• 제30권2호
• /
• pp.185-199
• /
• 2019

Modular construction is an emerging technology to accommodate the increasing restrictions in terms of construction period, energy efficiency and environmental impacts, since each structural module is prefabricated offsite beforehand and assembled onsite using industrialized techniques. However, some innate structural drawbacks of this innovative method are also distinct, such as connection tying inaccessibility, column instability and system robustness. This study aims to explore the theoretical and numerical stability analysis of a tenon-connected square hollow section (SHS) steel column to address the tying and stability issue in modular construction. Due to the excellent performance of composite structures in fire resistance and buckling prevention, concrete-filled steel tube (CFST) columns are also taken into account in the analysis to evaluate the feasibility of adopting composite sections in modular buildings. Characteristic equations with three variables, i.e., the length ratio, the bending stiffness ratio and the rotational stiffness ratio, are generated from the fourth-order governing differential equations. The rotational stiffness ratio is recognized as the most significant factor, with interval analysis conducted for its mechanical significance and domain. Numerical analysis using ABAQUS is conducted for validation of characteristic equations. Recommendations and instructions in predicting the buckling performance of both SHS and CFST columns are then proposed.

• 한국강구조학회 논문집
• /
• 제11권4호통권41호
• /
• pp.385-395
• /
• 1999

철골구조물에 각형강관기둥과 H형강보가 많이 사용되는 추세에 있다. 각형강관기둥과 H형강보의 접합부는 그 회전강성이 약한 것으로 알려져 있다. 그러한 약점을 보완하기 위해서 콘크리트 충전된 각형강관과 H형강보 접합부에 대한 많은 고안이 이루어지고 있다. 그런데 이렇게 고안된 모든 접합부 모델에 대해서 실험을 행할 수는 없으므로 수치해석 모델링과 수치해석에 의해 그 강도를 규명해야 한다. 본 논문에서는 유한요소 모델링기법을 연구하고 접합부의 강성을 좌우하는 여러요소 즉 콘크리트 강도, 각형강관두께, 축력의 크기 및 편심위치 등을 변화시켜 접합부 강성변화에 어떤 영향을 미치는지 살펴보았다.

• Steel and Composite Structures
• /
• 제4권2호
• /
• pp.95-112
• /
• 2004

A series of tests was performed to consider the behaviour of short composite columns under axial compressive loading, covering a range of S275 and S355 grade steel square hollow section filled with normal and high strength concrete. The interaction between the steel and the concrete component is considered and the results show that concrete shrinkage has an effect on the axial strength of the column. Comparisons between Eurocode 4, ACI-318 and the Australian Standards with the findings of this research were made. Result showed the equation used by the ACI-318 and the proposed Australian Standards gave better predication for the axial capacity of concrete filled SHS columns than the Eurocode 4.

• Steel and Composite Structures
• /
• 제42권1호
• /
• pp.91-106
• /
• 2022

Concrete-filled square stainless steel tubes (CFSSST), which possess relatively large flexural stiffness, high corrosion resistance and require simple joint configurations and low maintenance cost, have a great potential in constructional applications. Despite that the use of stainless steel may result in high initial cost compared to their conventional carbon steel counterparts, the whole-life cost of CFSSST is however considered to be lower, which offers a competitive choice in engineering practice. In this paper, a comprehensive experimental and numerical program on 24 CFSSST stub column specimens, including 3 austenitic and 3 duplex stainless steel square hollow section (SHS) stub columns and 9 austenitic and 9 duplex CFSSST stub columns, has been carried out. Finite element (FE) models were developed to be used in parametric analysis to investigate the influence of the tube thickness and concrete strength on the ultimate capacities more accurately. Comparisons of the experimental and numerical results with the predictions made by design guides ACI 318, ANSI/AISC 360, Eurocode 4 and GB 50936 have been performed. It was found that these design methods generally give conservative predictions to the ultimate capacities of CFSSST stub columns. Improved calculation methods, developed based on the Continuous Strength Method, have been proposed to provide more accurate estimations of the ultimate resistances of CFSSST stub columns. The suitability of these proposals has been validated by comparison with the test results, where a good agreement between the predictions and the test results have been achieved.