How does the angle of diagonal bracing in a lattice tower primarily affect its resistance to torsional forces?

The angle of diagonal bracing in a lattice tower primarily affects its resistance to torsional forces by influencing the efficiency of shear force distribution within the tower structure. Torsional forces are twisting forces that can cause the tower to rotate around its vertical axis. Diagonal bracing members, which are structural elements arranged diagonally between the tower's legs, resist these forces by acting in tension and compression. A steeper angle of diagonal bracing (closer to vertical) generally results in a greater proportion of the applied torsional force being resolved into axial forces (tension and compression) within the bracing members themselves. Axial forces are forces acting along the length of a structural member. This is more efficient at resisting torsion than if the bracing angle were shallower (closer to horizontal), which would require the tower legs to bear a larger share of the shear forces. Optimal torsional resistance is achieved when the bracing angle is designed to effectively distribute the torsional load as axial loads across the bracing system, minimizing stress concentrations and preventing the tower from twisting excessively. In essence, the angle determines how efficiently the bracing transforms the twisting force into tension and compression within its members, rather than allowing the legs to bear the brunt of the rotational stress.