Taking into account the stiffness of steel ropes when evaluating their tension force based on the results of measuring the natural frequency of oscillations

The results of a previously performed inspection of steel ropes of a cable-stayed transition, where the tension force was determined by the frequencies of their transverse vibrations, are considered. The features of the technique for performing measurements of the natural frequencies of the rope oscillations are revealed, concerning the method of excitation of oscillations, their orientation and the volume of an informative sample of recorded frequencies. The physical model underlying the measurement technique does not take into account the elastic bending response of the rope and viscous friction. It is shown that taking into account such factors allows not only to improve the accuracy of measuring the tension force, but also opens up the possibility of detecting defects in the rope. For example, the breakage of the rope fibers, its thinning as a result of corrosion or abrasion leads to a decrease in flexural rigidity. A change in the state of the rope lubrication or the penetration of liquid into the rope leads to a change in the damping coefficient of its oscillations. The results of the study can be used to create monitoring systems for the state of steel ropes.

cable-stayed bridge, steel rope, steel cable, standing waves, rope tension force, bending stiffness, vibration damping, condition monitoring