Influence of the Reynolds-Number on Flow Induced Vibrations of Generic Bridge Sections

Abstract

Bridge structures are often composed of more or less bluff bodies. A main point of the lecture is the question: In which case does the Re. No. play a significant role, in particular concerning their influence on the propensity to flow induced vibrations. The paper reviews the results of experiments carried out over a wide range of Reynolds numbers in a high pressure windtunnel. The two dimensional bodies investigated are: a generic Tacoma section, a sharp-edged, trapezoidal-shaped bridge section (approach span of “Great Belt” bridge) and a rectangular section with aspect ratio 1:5. Concerning the aeroelastic behaviour of the simplified Tacoma section, response curves will be presented, showing the occurrence of nonlinear vortex resonance phenomena. In case of the Belt section, variation of Re No led to significant changes in the force coefficients and St. No., caused by changes in the topological structure of the separated flow. For an angle of incidence α = 4° the rectangular cylinder shows strong Re No effects in particular in the curve of the lift coefficient. Generally one can say, bluff bodies having sharp-edged sections may suffer pronounced Reynolds-number effects as well.