Axial partial compressive behavior of round-ended concrete-filled steel tubular columns

The paper conducted 19 partially and 5 fully loaded tests on round-ended concrete-filled steel tubular (CFST) columns. These tests revealed that the ultimate strengths of round-ended CFST columns under partial load declined as the cross-sectional aspect ratio or partial compression area ratio increased. However, the use of a top plate effectively enhanced their ultimate strengths. In addition, a finite element model (FEM) was utilized to generate 487 large-size models to explore the confinement effect, stress distribution, and parametric effects. Since there are no specific design standards available for round-ended CFST columns, the paper has evaluated the applicability of design methods provided in Eurocode 4, AISC 360-16, and Chinese code GB50396 which are intended for circular, square, or elliptical CFST columns for round-ended CFST columns under partial load. However, these existing design techniques showed inaccurate and dispersed resistance predictions for round-ended CFST columns. Therefore, an effective simplified method for forecasting the resistance predictions of round-ended CFST columns under the partial load has been proposed based on the testing results and FEM analysis.