Defect detection in strand wires within the anchorage area of high tensioned cables

摘要

Assessment of cables of cable supported structures is complicated there these elements are oftenrndifficult to inspect visually. Owners of these kind of structures are facing a lack of information onrnthese key elements of their structures.rnThis paper presents a new promising technology that can provide a solution for this problem byrnproviding information on the condition of the cables inside the anchorage area.rnIn general the anchorage areas of cables is the most vulnerable part of cables due to waterrningress, lower protection of the wires and fatigue issues. Typical defects in these areas arerncorrosion, cross section loss and wire breaks.rnThe development of this technology over the past years in cooperation with the French NationalrnLaboratory IFSTTAR has resulted in a fully proven and operational tool that recently demonstratedrnits value on a full scale application on one of world’s largest stay Cable Bridge where it successfullyrnassessed the condition of the cables behind the bottom anchorage. Over 80 000 wires have beenrninspected for defects on this project. Other structural owners have acknowledged the value of therntechnology by testing their cable anchorages.rnThe technology is based on Ultrasonic guided waves principle transmitted along a single wire of arn7 x 5 wire strand. This paper explains the principle of the technology, shows how it can berndeployed on site, and provide feedback from lab tests and real measurement on site.