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Span - the distance between two bridge supports, whether they are columns, towers or the wall of a canyon.
Types of Bridges
All beams in a truss bridge are straight. Trusses are comprised of many small beams that together can support a large amount of weight and span great distances.
Consists of a horizontal beam supported at each end by piers. The weight of the beam pushes straight down on the piers. The farther apart its piers, the weaker the beam becomes. This is why beam bridges rarely span more than 250 feet.
The arch is squeezed together, and this squeezing force is carried outward along the curve to the supports at each end. The supports, called abutments, push back on the arch and prevent the ends of the arch from spreading apart.
Case Study: Tacoma Narrows Failure
The first Tacoma Narrows suspension bridge collapsed due to wind-induced vibrations on Nov. 7, 1940. The bridge over engineered it to withstand hurricane winds, but the wind that day was only 40 mph… what happened!?