Foundations, most certainly will be made of reinforced concrete; the towers can either be made of structural steel or reinforced concrete, the deck can be made of steel, or concrete or a mix of those, the suspension cables are, nowadays, made of high-tensile parallel strands or wires and the hanger cables are usually of wire steel stranded cables.
Suspension bridge, bridge with overhead cables supporting its roadway. One of the oldest of engineering forms, suspension bridges were constructed by primitive peoples using vines for cables and mounting the roadway directly on the cables. A much stronger type was introduced in India about the 4th century ad that used cables of plaited bamboo and later of iron chain, with the roadway suspended.
How? More durable concrete, the addition of stainless-steel rebar to reduce cracking and buckling, molten-zinc spray-on coatings for steel, and the inclusion of corrosion-monitoring sensors have helped extend the life of bridges. The increased strength of newer steel helps as well. Where 36000 pounds per square inch of capability was once the norm, now you can expect nearly double that: 70000 psi. That means engineers can achieve the same strength with less material, reducing cost and weight and optimizing bridge performance.
Simple Suspension Bridge Model
Your lengths of string can vary depending on the distance from pylon to pylon, your total span of the bridge, and your height you want the decks to be above the ground. These are some distances I used, for reference. Explore with different lengths to see which bridge looks nicer or more realistic.
How was the bridge built?
Folklore says that a the first rope across the gorge was taken by kite, or even by bow and arrow! The simplest and much more likely event was that common hemp ropes were taken down the side of the gorge, across the river by boat and pulled up the other side. These ropes were used to haul six wire cables across the Gorge, which were planked across and bound with iron hoops, making a footway.
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Picture a standard beam bridge, one with large columns underneath to support it and a flat roadway. The bridge might seem solid as cars and trucks pass over it daily, but now picture that bridge in the middle of an earthquake. The sturdy supports attached to the ground are now torn apart, shredding the bridge.
How to Build a Suspension Bridge
Set the anchors for the cables. The cables, which bear most of the weight of the decking, must be anchored in solid bedrock or enormous concrete anchors on each side of the bridge. These cables are then spread into the rock or concrete to more evenly distribute the weight.
Suspension Science: How Do Bridge Designs Compare?
Suspension bridges are a bit more complicated. They comprise a deck (the long straight part that includes the road), cables and towers. The cables stretch between the towers and help support the weight of the deck and its load. In this type of bridge the cables are under tension and the towers undergo compression.