In one-dimensional modelling, the tower is treated as a cantilever beam-column with varying inertia along the height. The properties of the beam are calculated assuming that the legs are the flanges of an equivalent I-beam so that the moment of inertia and area can be used in calculating the forces due to bending and axial loads. But the effect of bracing and torsion are very difficult to include mainly because the contribution of each of these in resisting the load as a beam can be done only by approximations. Further, as the beam is non- prismatic and skeletal, the approximations completely neglect the integral action of the members. This brings in disproportionate distribution of loads on to the various components resulting in either over-design or under-design