Concrete- and timber-filled steel tubes (CTFSTs) have gained interest and popularity over the past few years. This popularity is mostly due to the high compressive strength of the timber, which makes it a perfect choice (as a green alternative) to be substituted (at least) with part of the concrete. The concrete, on the other hand, has an adverse effect on the environment owing to the substantial CO2 emission of the cement. Following the past experimental research projects, this paper addresses the effect of a comprehensive set of geometric and material variables in the novel composite columns including timber and concrete infills. A numerical and analytical study was carried out to elaborate on the axial capacity, energy absorption, slenderness and capacity-to-mass ratio of 88 FE models. Very consistent results were obtained comparing the results of the models with the experimental data in the literature.
