Finite element model for tapered three layers composite columns (Stobie poles)

Abstract

A Stobie pole is a specific configuration of composite steel-concrete column which is being used widely as power poles in South Australia. It consists of two steel H sections, with the space between them filled with plain concrete. The two steel sections, and the concrete part in between, are connected by transverse bolts, which generate the composite action between them. These poles are tapered, from ground level to the top, and from the ground section to the toe. A 3D Finite element model (FEM) has been developed to analyse the structural behaviour of this type of composite column. This model considers the slippage between the different components e.g., the steel profile and concrete, bolt washers and steel profile, bolt shanks and the concrete, and the effect of the material nonlinearity of the steel profiles, steel bolts, and the concrete, including the damage of the concrete (in tension and compression). Also, the axial tensile forces initiated in the bolts because of the tightening is simulated to get the real behaviour of these poles. After defining the boundary and load conditions, the 3D FEM's results agreed well with the experimental results. Load-deformation curves, failure progression, shear distribution between different components as well as the stress distribution have all been presented.