This paper deals with an extended analytical calculation model for the torsional load-bearing behaviour of assembled half-shell structures. The objective is to transfer the complex torsional load-bearing behaviour of segmented tower constructions into a simplified and mechanically comprehensible bar model. The presented approach determines the proportional load-bearing effects of shear force and torsion of a cut out single half-shell for a global torsional load based on the deformation equilibrium. The previous model approach – including the principle of load redistribution and the flexibility method – leads to a slenderness-independent determination of the load-bearing components. The developed method enables the specific isolation of the geometric influencing variables by separating the deformation-depending partial internal forces. In addition, the deformation approach can be used to investigate the influence of warping shear softness on the load-bearing behaviour of compact reinforced concrete segments with vertical joints according to the extended warping theory. Compared to the extended first-order warping torsion, the significantly simplified deformation calculation based on the second-order tension rod analogy leads to sufficiently accurate results. In general, the internal force calculation is considered to be extremely sensitive to the smallest changes, so that the improved and much more accurate approach finds its application. The numerical validation leads to very good matches of the internal forces as well as the deformations and stresses.