Magnetic NDT and Computer Modeling of Steel Rope Deterioration in Suspended Bridges

A combined approach to strength assessment of stay ropes in suspension bridges is considered. The rope working condition is analyzed by in-situ magnetic testing, computational assessment of ultimate breaking load and evaluation of residual margin of safety. The diagnostic parameters - distributed and/or local faults in wires - are used as input data for mechanical model of rope structure. The model allows calculating the stresses in each wire, simulating the degradation process and evaluating the rope breaking tensile load. The safety factor of deteriorated rope is considered as a generalized parameter that specifies the rope safe operation as an element of bridge stay arrangement. Examples of integrity analysis of stranded stay ropes and locked coil stay ropes are presented.