A unified formulation for circle and polygon concrete-filled steel tube columns under axial compression

Abstract

Current design practice of concrete-filled steel tube (CFST) columns uses different formulas for different section profiles to predict the axial load bearing capacity. It has always been a challenge and practically important issue for researchers and design engineers who want to find a unified formula that can be used in the design of the columns with various sections, including solid, hollow, circular and polygonal sections. This has been driven by modern design requirements for continuous optimization of structures in terms of not only the use of materials, but also the topology of structural components. This paper extends the authors' previous work [1] on a unified formulation of the axial load bearing capacity for circular hollow and solid CFST columns to, now, including hollow and solid CFST columns with regular polygonal sections. This is done by taking a circular section as a special case of a polygonal one. Finally, a unified formula is proposed for calculating the axial load bearing capacity of solid and hollow CFST columns with either circular or polygonal sections. In addition, laboratory tests on hollow circular and square CFST long columns are reported. These results are useful addition to the very limited open literature on testing these columns, and are also as a part of the validation process of the proposed analytical formulas. Keywords：Concrete-filled steel tube (CFST), hollow and solid section, circular and polygonal section, load bearing capacity Notations sc f combined strength of CFST sc ϕ stability factor of CFST 0

Nonlinear finite element analysis of double skin composite columns subjected to axial loading

“…Yu et al [51] proposed an equation confirming the experimental ultimate axial strength results. The formula was for the single skin solid and hollow section CFST columns and presented as follows:…”

“…In this study, the modified formulas were utilized as given below. In addition, in the literature, there are some proposed empirical models which were developed or derived by the researchers such as Uenaka et al [2], Han et al [50], Yu et al [51], and Hassanein et al [52]. This section also includes the explicit presentation of these proposed empirical models.…”

Study on Axial Compression Bearing Capacity of Reinforced Concrete Filled Steel Tube Members

“…The yield and ultimate strengths for the steel were obtained in the steel tensile tests, which show that both the steel tube and reinforcement have very good ductility. The concrete cubic compressive strength ck f is used to calculate the compressive strength of the prism by using : 2 k is the conversion factor，for ordinary strength concrete, 2 0.67 k  ).…”

“…Extensive studies have been conducted on the static and dynamic analyses, and the fire performance of CFST members [1][2][3][4][5][6][7][8][9][10]. For example, Han et al [1], Yu et al [2], Dundu et al [3], Dai et al [4] studied the compressive strength of CFST members. Han et al [1], Yu et al [5], Prabhu et al [6] investigated the axial compression performance of CFST members encased by various different materials, such as concrete, FRP and CFRP.…”

Study of recycled concrete–filled steel tubular columns on the compressive capacity and fire resistance

“…According to the analytical solution 25,26 for CFST members in the elastic phase, the effective axial stresses with confining effect on concrete and steel sections (i.e. s c and s s ) are the superposition of the uniaxial compressive stress using the plane strain condition…”