Yi Sun-sin Bridge: High Speed Wind Tunnel Tests of Twin Box Girder

This paper presents experimental results for twin box girder of the Yi Sun-sin Bridge in order to investigate the sensitivity of the Reynolds numbers on aerostatic force coefficient. High speed wind tunnel tests on 1:30 scale sectional model were carried out at the aeronautical wind tunnel in Korea Air Force Academy. It was found from the tests that the drag and lift coefficients revealed significant decrease of nearby 23% at supercritical region. The safety rail prevented the Reynolds number dependency of aerostatic force coefficients at negative angles of attack. In similar way, the boundary layer trip strip attached at bottom surface of girder removed the Reynolds number dependency of aerostatic forces by fixing the location of flow transition. The pressure coefficients at girder surface near the gap significantly changed as the Reynolds number increase because of variation of the locations of flow separation and transition. The significantly unbalanced division of the drag force and lift forces at each box girder appeared in subcritical region was gradually resolved, and both girders almost equally divided the forces at supercritical region.