November 02 (Thursday)
다상유동(III)
Oral,
제1발표장(201A호),
14:10~15:10
  • Chair :
  •  신원규(충남대)
Th01E-5
14:10~15:10
Tacoma Narrows Bridge의 붕괴 과정
김우진, 최해천(서울대학교)
The Tacoma Narrows Bridge (TNB) was collapsed in 1940 at the wind speed (U) of 18m/s corresponding to Re = 3000000 based on the height (h = 2.4m) of the deck. The deck was lifted by two cables with 110 hangers and each cable was suspended by two towers. The deck experienced a vertical vibration with the spanwise wavelengths (λ) of 1/4 and 1/4.5 of the deck length (L) and the non-dimensional frequency of St = fh/U = 0.08, followed by a torsional vibration with λ = L and St = 0.027. We investigate the procedure before the collapse of the TNB using numerical simulation with fluid-structure interaction. We consider Re = 300 and 1000 because the non-dimensional frequency of vortex shedding is not much changed by the change in the Reynolds number due to a fixed separation point at the leading edge of the deck. A nonlinear model for a suspension bridge (Arioli & Gazzola, 2017) is used for the motion of the TNB. Initially, two-dimensional vortex shedding is generated with a weak vibration of the deck. Then, the deck oscillates vertically with λ = L/4.5 and St = 0.09, together with three-dimensional vortical structures behind the deck. Finally, the deck oscillates torsionally with λ = L and St = 0.033. These predicted vibrations of the TNB are in good agreements with those occurred in 1940.
Keywords : Tacoma Narrows Bridge, Fluid-structure interaction, Vortex shedding, Lock-in phenomenon
Paper : Th01E-5.pdf

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