An enhanced unified model for the self-damping of stranded cables under aeolian vibrations

A new formulation for cable self-damping, based on a mechanical model for the hysteretic bending of metallic strands, is derived by extending a previous model by the authors. It accounts for the possible occurrence of micro-slip phenomena at the wire contact surfaces and distinguishes between the different dissipation mechanisms that can take place before and after the activation of the gross-sliding between the wires. The dissipated energy per unit of length is shown to depend on the cube of the bending curvature in the no-sliding regime, and on the square of the curvature when gross-sliding takes place. A specific value of the bending curvature is proposed to switch between the two dissipation mechanisms. The resulting unified dissipation model can be used to compute the dissipated power in the mono-modal steady-state vibrations characteristic of the Energy Balance Principle. The proposed model allows to recover, as limit cases, the exponents controlling the dissipated power evaluated with different theoretical models under both assumptions of micro-slip and gross-sliding. Moreover, it gives very good predictions of the experimentally measured vibration amplitude on a field-line. The results obtained make mechanical models for the prediction of cable self-damping viable tools that can be adopted in the practice.