Estimation of the Remaining Strength of Locally Corroded P. W. S. Ropes

Abstract

A method to estimate the remaining strength of locally corroded P. W. S. ropes was developed. In this method, the degree of corrosion first evaluated in terms of the loss of cross-sectional area by magnetic inspection. Second, the remaining strength is estimated from the area loss by a numerical simulation of the load-elongation behaviour of the corroded P.W.S. With this method the remaining strength was considerably lower than expected from the area loss, because the P. W. S. consists of wires corroded to various degrees. To verify the validity of this method, bundles of partially thinned wireswere examined as a model of locally corroded P.W.S. The area loss and the strength for these specimens were in good agreement with the actual values. The method was then used to evaluate the degree ofdeterioration of P.W.S. 75 ropes that had been seriously corroded during 15 years' exposure to weather as suspension members of roofing. Two P.W.S. 75's were removed from the roofing for replacementand then subjected to tensile test. The remaining strength of those ropes was successfully predictedbythis method.