Behavior of square tubed steel reinforced-concrete (SRC) columns under eccentric compression

• We report the behavior of square tubed SRC columns under eccentric compression.
• Local buckling was delayed since no axial load was directly applied on tube.
• Initial geometric imperfections were discussed in the FE analysis.
• A modified Eurocode 4 design method was adopted to calculate the ultimate strength.

This paper presents experimental and analytical studies on the behavior of square tubed SRC (TSRC) columns subjected to eccentric compression. Eight square TSRC columns were tested to investigate the effects of eccentricity ratio of the compression force, width-to-thickness ratio (B/t) of the steel tubes, and use of shear connector studs on the steel sections. The test results indicated that local buckling of the square tubes was delayed effectively since axial load was not directly applied on the steel tube. Buckling of the tube initially occurred when the load reached the ultimate value for the specimens with B/t ratio of 100, and buckling occurred earlier for the specimens with B/t ratio of 133 when the load reached 88% to 94% of the ultimate load. A nonlinear finite element (FE) model was developed using ABAQUS, in which the nonlinear material behavior and initial geometric imperfections were included. Good agreement was achieved between the predicted results using the proposed FE model and the test results. A modified Eurocode 4 design method was adopted to calculate the ultimate strength of square TSRC columns.