Long Term Load-Carrying Capacity of Eccentrically Compressed Concrete Filled Steel Tubular Members

The reinforced concrete-filled steel tube (RCFST) column solves several of the problems of the concrete-filled steel tube (CFST) column in practical engineering applications. Moreover, RCFST has a simple joint structure, high bearing capacity, good ductility, and superior fire resistance. From a structural safety perspective, designers prioritize the creep performance of CFST members in structural design. Therefore, the creep behavior of RCFST columns should be thoroughly investigated in practical engineering design. To study the influence of the creep behavior of RCFST columns under axial compression, this work analyzed the mechanical behavior of composite columns based on their mechanical characteristics under axial compression and established a creep formula suitable for RCFST columns under axial compression. A creep analysis program was also developed to obtain the creep strain–time curve, and its correctness was verified by existing tests. On this basis, the effects of the main design parameters, such as the stress level, steel ratio, and reinforcement ratio, on the creep behavior were determined and analyzed. The creep of the tested composite columns increased rapidly in the early stages (28 days) of load action; the growth rate was relatively low after 28 days and tended to stabilize after approximately six months. The stress level had the greatest influence on the creep of RCFST columns under axial compression, followed by the steel ratio. The influence of the reinforcement ratio on the creep behavior was less. The results of this study can provide a reference for engineering practice.

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“…Han and Wang [ 18 ] derived the relationship with the ratio of the principal stress in the three directions from experimental data.…”

Section: Creep Calculation Formulamentioning

confidence: 99%

Creep behavior of reinforced concrete-filled steel tubular columns under axial compression

2021

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“…For the past few years, scholars have studied deeply on the behaviors of traditional CFST members under axial load 7 , 8 , axial load-moment interaction 9 – 11 and pure bending 12 – 14 . The results show that the flexural capacity, stiffness, ductility, and energy dissipation ability are all strengthened and showed a good ductility failure of the CFST columns and beams due to the filling concrete of the interior.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on rubber concrete filled steel tube members under pure bending

Wang

Bai

et al. 2022

Sci Rep

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The test of four rubber concrete filled steel tube (RuCFST) members, one concrete filled steel tube (CFST) member and one empty member were conducted under pure bending. The main parameters were the shear span ratio (λ) from 3 to 5, and the rubber replacing ratio (r) from 10% to 20%. The bending moment-strain curves, the bending moment-deflection curves and the bending moment–curvature curves were obtained. The failure modes of core rubber concrete were analyzed. The failure mode of RuCFST members was bending failure from the results. The cracks of rubber concrete were distributed evenly and sparsely, and the filling of rubber in core concrete prevented the development of cracks. The shear span ratio has little effect on the behavior of the tested specimens. While the rubber replacing ratio had little effect on the bending moment capacity, but had some influence on the bending stiffness of the tested specimens. After filling in rubber concrete, the bending moment capacity and the bending stiffness can be improved compared with the empty steel tube specimen.

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Stability bearing capacity of concrete filled steel tubular columns subjected to long-term load

Lai

Gao²,

Yang

et al. 2023

Sci Rep

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Concrete-filled steel tube (CFST) are commonly used in modern building and bridge applications. Despite their popularity, studies on the investigation of the influence of long-term load on the stability bearing capacity of such elements are scarce. This study investigates how the key parameters including slenderness ratio (λ), axial load ratio (m), and eccentricity ratio (e/r) affect the stability bearing capacity of a CFST column under sustained load. Twenty three CFST columns were fabricated to investigate the effect of long-term load on the stability bearing capacity. Fourteen specimens were subjected to constant compressive loading for 462 days and then tested for failure. The remaining 9 were companion load-free specimens. A three-stage finite element method was used to predict the stability bearing capacity after creep. The results indicate that the stability bearing capacity of CFST columns decrease after being subjected to long-term load. Both the experimental and numerical results indicated that the load of steel tube for long-term load specimens reaching up to the elastic–plastic and plastic process was lower than that of the load-free specimens. Moreover, the corresponding strain of the creep specimens was greater than that of the load-free specimens when the member reached the maximum load. Benchmarking analyses have shown that the creep reduction coefficient (kcr) proposed for CFST columns can be used to predict the reduction of stability bearing capacity after creep. Furthermore, a collected database comprising 49 CFST specimens subjected to long-term load was used to investigate the proposed formulae for kcr. The results show that the formulae were consistent with the experiment results.

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Long Term Load-Carrying Capacity of Eccentrically Compressed Concrete Filled Steel Tubular Members

Cited by 3 publications

References 6 publications

Creep behavior of reinforced concrete-filled steel tubular columns under axial compression

Creep behavior of reinforced concrete-filled steel tubular columns under axial compression

Experimental study on rubber concrete filled steel tube members under pure bending

Stability bearing capacity of concrete filled steel tubular columns subjected to long-term load

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