Experimental assessment on the size effects of square concrete-filled steel tubular columns under axial compression. (15th April 2023)

• Record Type: Journal Article
• Authors: Gao, Pan; Zhou, Xuhong; Liu, Jiepeng; Lin, Xuchuan; Wang, Xuanding; Frank Chen, Y.
• Is Part Of: Engineering structures. Volume 281(2023)
• Publication Date: 2023-04-15
• Subjects: Square concrete-filled steel tube -- Size effect -- Large-dimension -- Ratio of width to thickness -- Axial compression; Structural engineering -- Periodicals; Structural analysis (Engineering) -- Periodicals; Construction, Technique de la -- Périodiques; Génie parasismique -- Périodiques; Pression du vent -- Périodiques; Earthquake engineering; Structural engineering; Wind-pressure; Periodicals; 624.105
• DOI: 10.1016/j.engstruct.2023.115706
• Languages: English
• ISSNs: 0141-0296

Abstract

Highlights: Square CFST columns up to 1000 mm in width were tested under axial compression. The difference in strength between the different thicknesses of steel tube used in the tests was only 18 MPa. The effects of size and width-to-thickness ratio on the steel tube stresses were discussed. A axial bearing capacity model considering the size effect was proposed for square CFST columns. Abstract: In this study, eight specimens with the sectional widths ( B ) of 200–1000 mm and the width-to-steel tube thickness ratios ( B / t ) of 40 and 50 were tested to failure under axial compression to investigate the size effects of square concrete-filled steel tubular (CFST) short columns, specifically those on the failure mode, composite elastic modulus, peak axial strain, peak axial stress, ductility index, strength index, and stress development. The test results indicate that the peak axial stress, ductility index, and strength index decrease with the increasing specimen size, while the failure mode and composite elastic modulus maintain relatively steady. Under the peak axial load, the longitudinal to yield stress ratio of steel tubes increases with the increasing specimen size, while the trend of transverse to yield stress ratio is opposite. The size effect on the transverse stress in the steel tube reduces the tube confinement effect, thus degrades the compressive strength of the core concrete. Compared to the test results, both the EC4 and the GB50936 codes are unconservative in predicting the strength of large square CFST columns. Therefore, a model considering the ratio of width to thickness ( B / t ) and specimen size is proposed to evaluate the axial bearing capacity of square CFST short columns.