Abstract
Steel beams with eccentric loads are subjected to combined bending and torsional moments that lead to lateral displacements, unwanted stresses at the top and bottom flanges, and global buckling along their length. To resist these displacements and stresses, horizontal stiffeners were used in the direction of the beam axis at locations of the beam’s web height. To conduct this study, Finite Element Modeling (FEM) was used to simulate these steel beams. The reliability of the FEM results was first verified by comparing them with the results of 25 steel beams that had been experimentally tested in previous studies, and the results showed high accuracy in modeling these steel beams. Secondly, a FEM analysis was performed on 70 steel beams, considering certain variables, namely the locations of the horizontal stiffeners relative to the beam’s web height, the width of the horizontal stiffeners, and the reduction in the spacing between the vertical stiffeners. The results showed that locating the horizontal stiffeners closer to the top or bottom flange enhances the beam’s resistance to eccentric loads. The placement of horizontal stiffeners near the flanges influences the stress distribution at their edges and the overall load capacity, with optimal locations at 10%, 20%, and 90% of the web height. Additionally, combining stiffeners at two web height locations increased capacity synergistically, though less than the sum of their individual effects. Using small-width horizontal stiffeners at low ratios of web height achieved similar efficiency to full-width stiffeners at higher ratios, allowing for material savings. Reducing the distance between vertical stiffeners by half also led to similar improvements to using steel beams with horizontal stiffeners of 20% or 90% of the web height. An interaction diagram was developed to predict the ultimate load capacity of steel beams under combined bending and torsion moments with varying horizontal stiffeners.