Evaluation on remaining bearing capacity and service life for parallel wire cable

Since 1980s China has forged more than one hundred cable-stayed bridges. With the passage of time, the stay cables of many bridges have been gravely corroded and some of them were broken causing collapses. In the grim situation, apprehensions about the safety of these cable-stayed bridges arise. This paper advances a series of pragmatic methods to attack inspection and evaluation of parallel wire cables.

First of all, a grading contrast standard for corrosive wires is established for the convenience of visual inspection. Inspections are then carried out on cables dismantled from cable-stayed bridges to find out the distributing rule of internal corrosion. Furthermore, a single wire modelling is built based on wire deterioration mechanism. It is required that the modelling should consider the dual influences of corrosion (including homogenous corrosion and rust pit etc.) and fatigue, which can be adjusted through testing. On the basis of the single wire modelling, a parallel cable model can be applied to figuring out remaining bearing capacity and forecasting remaining service lives of the cables. Finally, the experimental values of the discarded cables are compared with theoretical ones to verify the precision of the theoretical analysis.

The method proposed in the paper was once applied to the inspection and evaluation of Shimen Bridge to determine the first replacement of stay cables. In the evaluation, the remaining service lives of the remaining cables were successfully estimated.