Comparison of the aerodynamics of bridge cables with helical fillets and a pattern-indented surface in normal flow

Kenneth Kleissl, Christos Georgakis

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Abstract

Over the last two decades, several bridge cable manufacturers have introduced surface modi-fications on the high-density polyethylene (HDPE) sheathing that is often installed for the protection of inner strands. The main goal of this is rain rivulet impedance, leading to the suppression of rain-wind induced vibrations (RWIVs). The modifications are based on re-search undertaken predominantly in Europe and Japan, with two different systems prevailing; HDPE tubing fitted with helical surface fillets and HDPE tubing with pattern-indented sur-faces. In the US and Europe, helical fillets dominate, whilst pattern indented surfaces are more common in Asia. Research into the effectiveness of helical fillets and pattern-indented surfaces has shown that, besides their potential to suppress rain-wind induced vibrations, they are also modestly reducing drag forces at design wind velocities. This is of particular interest to bridge design-ers, as wind on stay planes of long bridges can now produce more than 50% of the overall horizontal load on a bridge. Nevertheless, there is no definitive aerodynamic performance comparison between the two systems. One of the problems of comparing them lies in the fact that different researchers, in different facilities, with varying wind-tunnel flow characteristics and performance, have developed each separately. As part of a comprehensive review of the aerodynamics of existing cable surface modifica-tions, the resulting static force coefficients obtained from wind-tunnel tests on cables normal to flow and employing both systems are presented herewith and compared to those from a plain reference cylinder. This is the first known direct comparison of this type. Evaluation of lift force fluctuations and flow visualisation tests are also undertaken to obtain insight into the structures of the flow around the modified profiles.
Original languageEnglish
Title of host publicationInternational Conference on Wind Engineering
VolumeCD-ROM
Publication date2011
Publication statusPublished - 2011
Event13th International Conference on Wind Engineering - Amsterdam, Netherlands
Duration: 10 Jul 201115 Jul 2011
Conference number: 13
http://www.icwe13.org/

Conference

Conference13th International Conference on Wind Engineering
Number13
CountryNetherlands
CityAmsterdam
Period10/07/201115/07/2011
Internet address

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