AN EXAMPLE OF THE USE OF WIND TUNNELS FOR INVESTIGATING THE AERODYNAMIC STABILITY OF BRIDGES
THE LONGS CREEK BRIDGE IS A CABLE-STAYED ORTHOTROPIC GIRDER BRIDGE HAVING A MAIN SPAN OF 713 FEET 4 INCHES AND A TOTAL LENGTH OF 1,092 FEET. WHEN ERECTED IT WAS OBSERVED THAT THE BRIDGE WOULD VIBRATE IN VERTICLE FLEXURE WHEN THE WIND VELOCITY NORMAL TO THE BRIDGE WAS IN THE RANGE 25 TO 30 MPH. AMPLITUDES ARE HIGH AS 8 INCHES WERE OBSERVED. A TEMPORARY SOLUTION FOR DAMPING THE MOTION WAS DEVISED. WIND TUNNEL INVESTIGATIONS WERE THEN UNDERTAKEN TO OBTAIN A PERMANENT AERODYNAMIC SOLUTION AND IT WAS FOUND THAT THE BEHAVIOR OF THE BRIDGE COULD BE DUPLICATED IN THE MODEL EXPERIMENTS. VARIOUS MODIFICATIONS TO THE EXTERNAL SHAPER WERE EXAMINED, SOME OF WHICH SUCCESSFULLY ELIMINATED THE VIBRATION. THE MODIFICATION FINALLY ADOPTED INCLUDED SOFFIT PLATING BETWEEN THE GIRDERS AND TRIANGULAR EDGE FAIRINGS WHICH CONSIST OF A HORIZONTAL EXTENSION OF THE SOFFIT PLATING AND A SLOPING WEB. SINCE BEING MODIFIED THE BRIDGE HAS BEEN EXPOSED TO SEVERE WINDS INCLUDING SOME WHICH WOULD HAVE PREVIOUSLY CAUSED MOTION OF THE BRIDGE. NO MOTION OF THE MODIFIED BRIDGE HAS YET BEEN OBSERVED. /CGRA/
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Supplemental Notes:
- 32 Pp, 9 FiG, 3 PHOT, 13 REF
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Corporate Authors:
CANADIAN GOOD ROADS ASSOCIATION
OTTAWA, ONT.:
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Authors:
- Wardlaw, R L
- Ponder, C A
- Publication Date: 1969-10
Subject/Index Terms
- TRT Terms: Aerodynamics; Girder bridges; Orthotropic; Structural plates; Vibration; Webbing; Wind pressure; Wind tunnels
- Uncontrolled Terms: Model tests; Plates
- Subject Areas: Bridges and other structures; Highways;
Filing Info
- Accession Number: 00208210
- Record Type: Publication
- Source Agency: CANADIAN GOOD ROADS ASSOCIATION
- Files: TRIS
- Created Date: Oct 13 1970 12:00AM