Science Busts The Biggest Myth Ever About Why Bridges Collapse
“Just four months later, under the right wind conditions, the bridge was driven at its resonant frequency, causing it to oscillate and twist uncontrollably. After undulating for over an hour, the middle section collapsed, and the bridge was destroyed. It was a testimony to the power of resonance, and has been used as a classic example in physics and engineering classes across the country ever since. Unfortunately, the story is a complete myth.”
If you’ve only ever seen one bridge collapse ever, it was probably the Tacoma Narrows Bridge. On November 7th, 1940, high, sustained winds sent the bridge from an up-and-down undulation into a twisting, rocking pattern that led to the eventual collapse of the structure. It’s been used as a classic example of resonance at work, similar to how a wine glass will shatter when exposed to the right frequency pitch. While the shattering of glass is due to resonance, and it is a real phenomenon, the numbers just don’t add up for the bridge. Instead, it’s a much more intricate phenomenon that caused that infamous bridge collapse, known as flutter. If you’ve heard the resonance explanation, you’re not alone: it’s probably the most common misconception in all of physics and engineering!