Effects of Shear Studs in Composite Columns’ P-M Interaction Diagrams

Composite construction including composite columns are widely used in structural design. In the transmission towers’ industry, composite columns are replacing the old timber and steel adopted designs. Research on the capacity and behavior of these traditional columns has been previously performed, yet few researchers investigated the behavior of hybrid composite columns, such as concrete filled steel tube (CFST) with embedded steel section or embedded steel tube (double skin column) and studs. Besides the non-homogeneity in concrete composition, choosing the right geometry for embedded steel components and their distribution pattern in the column section presents a challenge in achieving maximum section capacity. This study focuses on developing the P-M Interaction diagrams for different geometrical column shapes highly used in the industry such as hexagonal, octagonal, decagonal shapes, and the effect of adding headed shear studs on such diagrams. Three-dimensional non-linear finite element models were built using ABAQUS to compare and validate the behavior of the transmission towers against experimental work. The models include detailed analysis and investigation of the concrete and steel components behavior up to failure using concrete damage plasticity (CDP) and bilinear elasto-plastic model respectively. Good comparison between the FE results of such sections and previously studied columns has been achieved which leads to studying and investigating multiple forms of composite transmission towers. P-M Interaction diagrams were constructed for the proposed shapes for various diameter-to-steel thickness ratio (D/t) beyond AISC code limitations. Further extensive study was performed to investigate the effect of number of studs, studs’ dimensions, and studs’ arrangement in the cross-section and along the column length on the capacity of the columns. It was concluded from this study that certain arrangement and a smaller number of studs can give the desired capacity which is more economical and requires less efforts.