TACOMA BRIDGE NOVEMBER 1940

The evolution of long span bridge designs and construction. Choice of bridge deck section could have caused Tacoma bridge and other factors the designers underlooked then. But with time, many bridges of that nature have had improvement on their sections and shape as guided by various wind tunnel testing.
Tacoma bridge, Suspension bridge was one of the longest bridges at the time. The video clip was purposely for education and as a student, i had the opportunity to get first-hand information from the professor.
There are three wind induce vibrations to consider at design and construction stage. They include.
1. Turbulence induced: This is random effects due to fluctuation of wind inform of gusts.
2. Vortex Induced: this is periodic in nature where vortices are formed behind an object in question. The vortex shedding formed can easily excite the bridge.
3. Motion Induced Vibration: this is considered the most dangerous form that is created by both the bridge and surrounding wind moving together/working together.
In the case of Tacoma bridge, the bridge began moving at the begining of the wind effect and together the bridge and wind kept exciting the bridge to a point where more energy kept being pumped out of wind flow into the bridge exceeding all limits including capacity of the bridge and bridge elements. Torsional galloping was real.
The collapsed of the bridge changed the way engineers perceived long span bridge design and construction and more innovations set in and today, we have not registered serious cases as that at the time.