Bending Fatigue Response of Grouted Stay Cables; Research rept. (Mar. 2000 - Aug. 2006)

摘要

Both the Fred Hartman Bridge and the Veterans Memorial Bridge have experienced large-amplitude vibrations of the stay cables. A major concern resulting from these vibrations is the possibility of fatigue damage to the parallel, seven-wire, prestressing strand in the grouted stay cables and the overall safety of the bridges. An experimental investigation was conducted to determine the susceptibility of grouted stay cables to fatigue damage. Two series of experiments were conducted: twelve stay-cable specimens were subjected to bending fatigue loads in the first series and three small-scale specimens were subjected to bending fatigue loads in the second series. The test results indicate that fatigue damage is expected to be concentrated in the regions of highest bending stress: the ends of the stays and locations where a damper or restrainer induces local bending in the stay. The risk of fatigue damage was considered to be low at the tension ring, along the free length of the stay, and in the vicinity of unintentionally crossed strands. The acoustic monitoring systems installed on the Fred Hartman Bridge and the Veterans Memorial Bridge provided a reliable means of detecting wire breaks in the laboratory specimens.