definition of suspension bridge

A bridge has a very specific function: to unite two places to promote travel, trade and exchange in general. A bridge is a work of engineering but its function serves as a metaphor to refer to other contexts (communication bridges, bridge ideas or bridges as short vacation periods).

Classification of bridges

Bridges can be divided into two large groups: depending on the material used or its type. In terms of materials, the most common are wood, stone, metal and reinforced concrete. Each material has its advantages and disadvantages. For example, wood is inexpensive and building bridges with it is relatively fast, but wooden bridges are sensitive to the effects of weather. The use of reinforced concrete favors resistance and has a reduced maintenance cost. With regard to the type of bridges, there are three variants: the beam bridge, the arch bridge and the hanging bridge.

Hanging bridges

The suspension bridge is the only structure that can span more than a kilometer in distance and is normally used to connect two points separated by water, for example a bay or a river. Its construction is complex, since it requires properly distributing the loads of the cables and the anchors that support them.

Suspension bridges have to withstand various forces: their own weight, inclement weather and also the weight of road traffic. In the history of these constructions, collapses have occurred, as their design did not meet the necessary technical requirements.

To design a suspension bridge, engineers must take into account all the atmospheric phenomena that can affect them (mainly wind and hurricanes), as well as the force of gravity. On the other hand, suspension bridges can be a strategic target in situations of war or terrorist threat.

As there is nothing to support them in its lower part, the length of a suspension bridge is calculated by the section between the two towers that support it. You could say that the towers are like the poles of a clothesline, in such a way that if the towers fail the entire bridge collapses.

At present, most suspension bridges are manufactured using steel, as it is a ductile material, that is, it does not break easily. On the other hand, damping systems are often used to counteract possible lateral movements. With new techniques and materials, suspension bridges are increasingly longer and safer.

Photos: iStock - Leonardo Patrizi / gionnixxx