Structural behaviour of slender columns of high strength S690 steel welded H-sections under compression

This paper presents an experimental investigation into structural behaviour of slender columns of high strength S690 steel welded H-sections under axial compression. A total of seven slender columns with four sections of different cross-sectional dimensions and two different effective lengths were tested successfully. As expected, all of these columns failed in overall buckling about minor axes of their cross-sections, similar to those of conventional steel welded H-sections. Hence, these tests may be regarded to be confirmatory tests to structural behaviour of slender columns of high strength S690 steel welded H-sections under axial compression. No welding failure was observed after close inspection to all the columns after tests. It should be noted that the measured failure loads of these slender columns were directly compared with predicted resistances of corresponding sections based on their measured geometrical and materials properties according to current design rules given in European, Chinese, and American Steel Codes, namely, EN 1993-1-1, GB 50017-2003, and ANSI/AISC 360-16 respectively. As effects of residual stresses in S690 steel welded H-sections were considered to be proportionally less pronounced when compared with those in S355 steel welded H-sections, their buckling resistances should be significantly increased when compared with those S355 welded H-sections. It was found that the current design rules given in both EN 1993-1-1 and GB 50017-2003 underestimated buckling resistances of slender columns of S690 steel welded H-sections significantly, and use of a different buckling curve with an increased structural efficiency was suggested. However, the predicted resistances of these slender columns to the current design rules given in ANSI/AISC 360-16 were found to be close to the measured failure loads. Hence, they were considered to be applicable to design slender columns of S690 steel welded H-sections.