Which type of Bridge is more wind resistant, Cable Stayed, Suspension, or Arch Bridge?
(Experimental Design; District Assessment)


Introduction: Bridges have made our lives much easier. They have helped us cross long areas where it would be impossible to cross without sailing or boating across. Although it is a great invention it needs to be safe especially long bridges that are placed in windy areas. The three of the most well known type of bridges are suspension bridges, cable stayed bridges, and arch bridges. Which of these will be better for wind resistance?


The Suspension Bridge. Perhaps the most well known type of bridge is the suspension bridge. This bridge may look very similar to the cable stayed bridges but they are very different. Suspension bridges typically span from 70 meters to over 1000 meters. The world’s longest suspension bridge is the Akashi Kaikyo Bridge, in Japan, which is 3,911 meters across. Practically all suspension bridges are continuous girders across the area, which is being spanned. There are one or more towers erected in the middle of the bridge span. The girder is usually a truss so it helps support the bridge so it does not sway in the wind as much.

A truss:
The main cables pass over the towers and are attached to anchors that are placed at the end of the girders. The cables are placed on special structures that are on the towers. These special structures are called saddles and these saddles allow the cables to slide a little bit as the load goes from on side of the bridge to the other. To hold the actual girder up and keep it form falling there are other smaller cables, which are attached to the larger cable. These smaller cables are then attached to the girder. These cables keep the girder up. The weight of the anchors that are at the end of the girder is the practically the only thing that stabilizes the bridge. If someone were to remove the anchor and let the cables loose then the cables would slide way too much and the center span; which is between the towers would fall. The girder is suspended from the cables. An these cables stay up because of the towers; so there is a lot of tension on the towers. Here is a picture showing how a suspension bridge works.




The Arch Bridge. The arch bridge is another really famous type of bridge. Arch bridges typically span from 40 to 150 meters. The world’s longest Arch bridge is the New River Gorge Bridge, U.S.A. with a total length of 924 meters. . (http://www.matsuo-bridge.co.jp/) Unlike other bridges arch bridges work pretty well with bricks and stone. Arch bridges are the best type of bridge for crossing rivers and valley because arch bridges don’t need central towers to span an area. Arches are curved so it is very resistant to loads that would bend the girder. One of the types of arch bridges is the hinge-less arch. This arch uses no hinges at the foundations so a lot of compression is at the foundation there fore it can only be built where the foundation is very stable. The other more commonly used type of arch bridge is the tied arch. The girder of this bridge ties the arch together; therefore the load is transferred to the arch. This allows this type of arch bridge to be also built on unstable ground.


Hinge-less arch:



Tied arch:


Cable Stayed Bridge. Cable stayed bridges typically span from 110 to 480 meters. The longest cable-stayed bridge is the Ta1tara Bridge in Japan with a total length of 1,480 meters. (http://www.matsuo-bridge.co.jp/) When you first look at it the cable stayed bridge looks a lot like the suspension bridge. But it actually is really different. Just like the suspension bridge it is one girder with one or more towers erected near the middle. And cables are attached to these towers and then the cables are attached to the girder. This type of bridge is much lighter than suspension bridges. The cable attachment in the cable- stayed bridges is very different from the attachment of the Suspension bridges. Cable stayed bridges have no main cables that run across the whole bridge. Instead, they have many