NUMERICAL INVESTIGATION OF FILLET WELDS EFFECTS ON THE LOCAL BUCKLING OF BOX STEEL COLUMNS

Abstract

The local buckling has always been known as an undesirable and destructive phenomenon in steel structures. Thus, it is necessary to identify the effective factors in local buckling of the steel box column. Currently, box columns are generally fabricated by welding plates using fillet or groove welds with various manufacturing patterns, in terms of weld leg size and the overlap length of the plates. Hence, the evaluation of these patterns and also the control of local buckling in built sections seem to be essential. In this research, a variety of columns with different welding patterns, including groove and fillet welds with various overlap values and weld legs are numerically modeled and their local buckling behavior is studied in the finite element domain by using ABAQUS software. A suitable welding pattern is proposed by assessing the energy absorption, as well as stress distribution, stress concentration and finally local buckling in steel box section columns. The obtained results indicate that, the sections fabricated utilizing groove welds, have the best nonlinear performance. And also a suitable implementation of fillet welds to fabricate steel box columns is to consider 20% overlap length and 80% weld leg size to plate thickness as this model subject to small amount of local buckling. This model has shown less than 6% reduction in plastic capacity and energy absorption in comparison with groove welding. Another method is to use 50% for both overlap length and weld leg size to plate thickness. This model has shown less than 8% reduction in plastic capacity and energy absorption in comparison with groove welding. In addition, unsuitable implementation of fillet welds especially with small overlaps and weld leg sizes has shown a 12.5% reduction in plastic capacity and energy absorption, compared to groove welding