Twisting in the Wind

by Virginia Fairweather, Editor; Civil Engineering, 345 E. 47th St., New York, NY 10017,


Serial Information: Civil Engineering—ASCE, 1987, Vol. 57, Issue 10, Pg. 60-62


Document Type: Feature article

Abstract:

Wind tunnel tests are being used increasingly to test the aerodynamic stability of bridges. Many designers think these tests should be used early in the conceptual design stage, rather than after design is complete. The tests should be a design tool, rather than an aerodynamic check after the fact. For the Annacis Island cable-stayed bridge in Canada, wind tunnel tests were used early to refine the design for the best aerodynamic stability. The resulting refinements used 20% less steel than the original concept and thus reduced costs for the bridge, the world's longest span cable-stay. Early use of wind tunnel tests are also a safety check for bridges with very long spans that have the potential for instability during construction stages. Tiedowns and construction sequences can be tested for stability. There are two types of wind tunnel tests: aeroelastic, in which the entire bridge is modeled to scale, and section model tests, which are far less complex and costly. Increasingly, the aeroelastic tests are being used, but many designers think mathematical models for section tests are improving. As more research is done, designers will be able to make better use of this tool.



Subject Headings: Bridge tests | Wind tunnel | Cables | Cable stayed bridges | Mathematical models | Aerodynamics | Steel bridges

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