Which bridge collapsed 4 months after its completion in 1940 under a wind velocity of 19 m/s?

• A. Tacoma Narrows Bridge
• B. Golden Gate Bridge
• C. Brooklyn Bridge
• D. Sydney Harbour Bridge

Answer: (A)

Wind-induced aeroelastic flutter in long-span bridges is being tested here. When wind interacts with a slender, flexible deck, it can excite torsional and lateral vibrations. If damping is not enough, these vibrations can grow in a self-reinforcing loop, leading to catastrophic collapse.

In this case, the Tacoma Narrows Bridge, opened in mid-1940, collapsed about four months after completion under winds around 19 m/s. The wind induced torsional flutter that the structure couldn’t damp out, causing dramatic oscillations that tore the bridge apart. This famous failure illustrates how aeroelastic effects, not just simple gusts or static loads, can govern the stability of long-span bridges.

The other bridges listed did not fail under those wind conditions because their designs and aerodynamic characteristics differ—stiffer or differently shaped decks and different dynamic responses helped them withstand similar wind loads.