This article deals with the influence of adjacent segments on the torsional load bearing behaviour of assembled half-shell towers for wind energy turbines. The main objective is to detect and understand the load transfer in the modular tower structure considering the effects of adjacent segments. The engineering approach already developed for two assembled half-shells – based on the warping theory of thin-walled bars – is investigated for its applicability to the entire tower structure. Numerical comparative studies show that an adjacent half-shell pair level at the top and bottom is sufficient to take the influence of the entire tower structure into account. The adjacent segments affect the quantitative determination of the load-bearing components from shear force and torsion. Furthermore, the coupling conditions in the horizontal joint depend on the stress consideration and include only one (normal stresses via linear superposition) or both half-shells (shear stresses via Bredt shear flow). Therefore, an analytically and numerically based approach is presented that can be applied to the use case of segmental towers for wind turbines and the constant component heights of the precast segments. In this case, the methods take the decrease of the bending shear force component and the simultaneous increase of the torsion component in the system axis into account. The boundary conditions of the frame structure remain unaffected. Based on the further developed engineering model, the complex torsional load-bearing behaviour and the stress state in the horizontal joint of modular tower structures can now be analytically determined in the compressed and static friction condition based on the warping theory of thin-walled bars.