Bridges and Other “static” Structures
How does the suspension bridge support the roadway?
The longest suspension bridge in the world is in Kobe, Japan. The Akashi Kaikyo spans a distance of 1,991 meters (6,532 feet). The total length of the bridge is 3,911 meters (12,831 feet). This $3.3 billion bridge took 12 years to build and is designed to withstand 8.5-Richter scale earthquakes and 178 mph winds. It weathered the 7.2-Richter earthquake that killed 5,000 citizens of Kobe in January 1995. The only damage sustained by this incredibly well engineered bridge was that one of the piers and anchorages shifted a little less than 1 meter. This high-tech bridge uses pendulums within the massive vertical towers to counteract dangerous bridge movement produced by seismic activity. These high-tech mechanisms move against the motion of the bridge, stabilizing it and keeping drivers on the bridge relatively safe.
The twenty longest bridges in the world are all suspension bridges. Suspension bridges are able to span huge distances because the long cables suspending or holding up the roadbed are draped over a set of tall vertical towers called pylons. The pylons support the suspension cables from which vertical cables are attached that lift the deck. The ends of the suspension cables must be anchored into the ground at each end of the bridge to exert the tension forces on the cables.
The first known suspension bridge was constructed in the seventh century C.E. by Mayans at their capital Yaxchilan, Mexico. It spanned 100 meters.