This study presented a detailed structural evaluation of the behavior of composite columns under the effect of eccentric loads. The study focused on the impact of circular and square openings in the steel section. The study was carried out on 10 composite column specimens with different opening sizes and at three positions in the flanges and the web. The effect of these openings on the load-carrying capacity of the columns, as well as the slip behavior between the concrete and the steel section and their interaction, was studied. The study also aims to compare the effects of openings with those of shear studs and to explore the extent to which openings can replace shear studs to improve the structural efficiency of composite columns and simplify the construction process. The results of the study showed that the use of openings, especially those in the flanges, reduces slip and friction between the steel section and the concrete, thereby increasing the efficiency of force transfer between the concrete and the steel section and enabling them to act as a single element. Square openings reduced slip by 51.5%, while circular openings reduced it by 43.4%. Accordingly, this study represents an essential contribution to improving the design of composite columns, enhancing structural performance, and leveraging the mechanical properties of the section itself during self-connection with concrete to ensure load transfer, as well as the possibility of replacing shear studs with openings in future designs.
