Suspension Bridge Sway: Vortex-Shedding Resonance (2D)

This 2D companion isolates the actual mechanism behind the 3D bridge's sway: a forced, damped torsional oscillator representing the deck's twisting mode, driven by wind-induced vortex shedding whose frequency is set by the Strouhal relation f_v = St·V/D. A side panel exposes wind speed, deck width, the structure's torsional natural frequency and its damping ratio; a live resonance-response curve plots the classic amplification curve for the current damping and marks exactly where the current wind conditions sit on it, while a twist-history strip and a structural-status readout (SAFE / WARNING / COLLAPSE RISK) make the Tacoma-Narrows-style danger of driving the shedding frequency toward resonance directly visible instead of implied.