How did the Broughton suspension bridge collapse?
On 12 April 1831, the bridge collapsed, reportedly due to mechanical resonance induced by troops marching in step. As a result of the incident, the British Army issued an order that troops should “break step” when crossing a bridge.
Why do soldiers march out of step on a bridge?
At a certain point, the bridge would start oscillating to the same rhythm as that of the marching steps. This oscillation would reach a maximum peak when the bridge can no longer sustain its own strength and hence collapses. Therefore, soldiers are ordered to break their steps while crossing a bridge.
How can bridge resonance be prevented?
In order to mitigate fully the resonance effect in a bridge, engineers incorporate dampeners into the bridge design to interrupt the resonant waves and prevent them from growing. Another way to halt resonance is to give it less room to run wild.
What is the mechanical resonant frequency?
Mechanical resonance. Mechanical resonance is the tendency of a mechanical system to respond at greater amplitude when the frequency of its oscillations matches the system’s natural frequency of vibration (its resonance frequency or resonant frequency) than it does at other frequencies.
What is the most famous bridge collapse?
Here are four of the deadliest bridge collapses in the U.S. since 1967.
- Sunshine Skyway (1980) — Tampa Bay, Fla.
- Cypress Street Viaduct (1989) — Oakland, Calif.
- Silver Bridge (1967) — between Point Pleasant, W.V. and Gallipolis, Ohio.
- Big Bayou Canot Bridge (1993) — Mobile, Ala.
Why are soldiers asked to break their steps?
When a troop crosses a suspension bridge, the soldiers are asked to break steps. The reason is that when soldiers march in steps, all the separate periodic forces exerted by them are in same phase and therefore forced vibrations of a particular frequency are produced in the bridge.