Experiences with non-destructive examination on rope terminations and fittings on selected examples

Bridge ropes and guy ropes are used as high-strength tension members in civil engineering. Depending on the design of the bridge structure the ropes may be either carrying ropes or ropes for suspension - or cable stayed bridges. Guy ropes are also used in radio towers, steel chimney stacks, roof systems and similar structures. Usually their life expectancy is affected by static load, pulsating tensile stress and corrosion. There are no generally valid calculation methods, or at most only inadequate ones, by which the aforementioned three critical variables can be determined. Damage such as wire breaks and corrosion on the free length of the ropes will be detected principally by means of a magneto-inductive testing method. Damage frequently occurs to high-strength tension members in areas which are not freely accessible, for example in the transition between the rope or wire bundle and the sockets, below a mounted clamp or a deflection saddle. For examinations in these zones an ultrasonic (UT) method has been found to be appropriate. With this it is possible to detect even small levels of damage, such as cracks in wires, complete wire breaks and heavy corrosion scars. This paper describes the usage of the ultrasonic technique for the examination of rope terminations and fittings built in bridges and cable stayed constructions with some examples.

 Author(s): O. Gronau, J. Klein & H. Lobert