EngineeringDisasters!!!

1831Timeline: Broughton Suspension Bridge

One of Europes first suspension bridges was built in 1826 by the wealthy John Fitzgerald.

On 12 April 1831, the bridge collapsed due to the vibration caused by the marching of soldiers.

Timeline: 1859Angers Bridge:

Angers Bridge was a suspension bridge over the Maine River in Angers, France.

The bridge collapsed on 16 April 1850, while a battalion of French soldiers was marching across it, killing over 200 of them.

Timeline: 1940Tacoma Narrows Bridge:The 1940 Tacoma Narrows Bridge was a suspension bridge in the U.S. state of Washington, it opened to traffic on July 1, 1940, and dramatically collapsed on November 7 of the same year.

From the time the deck was built it began to move in windy conditions, and the bridge's main span finally collapsed under 64 km/h wind conditions on November 7, 1940.

Timeline: 2000Millennium Bridge:The Millennium Bridge is a steel suspension bridge for pedestrians crossing the River Thames in London, linking Bankside with the City of London, with the opening in June 2000.

Unexpected lateral vibration caused the bridge to be closed on 12 June 2000 for modifications.

Resonance Phenomenon !!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. It may cause violent swaying motions and even catastrophic failure in improperly constructed structures including bridges, buildings and airplanesa phenomenon known as resonance disaster.

Natural Frequency :

Dynamic Loads:1- People movements in buildings2- Working machines in buildings3- Moving cars on bridges4- Wind loads on structures5- Earthquakes6- Impact loads such as water waves

1831Timeline: Broughton Suspension Bridge Resonance

On 12 April 1831, the bridge collapsed, reportedly due tomechanical resonanceinduced by troops marching in step.

Timeline: 1859Angers Bridge Resonance:

The third battalion arrived during a powerful thunderstorm when the wind was making the bridge oscillate. When the soldiers began to cross, they gave the wind still more purchase.

The soldiers had been ordered to break step and to space themselves farther apart. However, their efforts to match the swaying and keep their balance may have caused them to involuntarily march with the same cadence, contributing to theresonance.

Timeline: 1940Tacoma Narrows Bridge:Resonance or Aeroelastic Flutter??!!

Timeline: 2000Millennium Bridge Resonance:The natural sway motion of people walking caused small sideways oscillations in the bridge, which in turn caused people on the bridge to sway in step, increasing the amplitude of the bridge oscillations and continually reinforcing the effect causing the resonance.

The Problem was fixed by : Dampers

DampingTypically, the dampers are huge concrete blocks or steel bodies mounted in skyscrapers or other structures, and moved in opposition to the resonance frequency oscillations of the structure by means of springs, fluid or pendulums.

Taipei 101

Burj Khalifa