CABLE-STAY CONUNDRUM

Abstract

Wind- and rain-induced vibrations of cables on cable-stayed bridges are a relatively new phenomenon. While some observers report hearing about such vibrations ten or 12 years ago, typically in Japan and Europe, it is only in the past few years that research has begun here in the United States. A study coordinated by the Texas Dept. of Transportation centers on vibrations at the Fred Hartman bridge, Baytown, Tex., which was opened in 1995, and the Veterans Memorial bridge in Port Arthur, Tex., which opened in 1991. The University of Texas, Austin, Texas Technological University, the University of Kentucky and Johns Hopkins University are contributing to the study and the Virginia firm of Whitlock, Dalrymple Poston & Assoc., working with these institutions. This article explores the possible reasons for the vibrations, as well as proposed remedial systems. Among them are restraining systems, dampers and strakers. The vibrations cause mororists concern, and can cause metal fatigue and other problems. Remediation can be costly. Design procedures are also suggested. A sidebar discusses the interim remediation work at the Fred Hartman bridge, and offers comments from engineers who have designed many cable-stayed bridges.