Math in Building Bridges

What is building bridge?

Building bridges has already had a long history. Nowadays, there are over half a million bridges in the United State. Besides, as we observed, we can know that not all the bridges looks similar. They have many different shape and different size depend on their features. But do you know how the bridges work and how do engineers use math to build the bridges?

Steel Truss Road Bridge

When architects are building a bridge, they need to concern it’s load-bearing capacity. For example, Steel Truss Road Bridge builds up with some triangles. Therefore, the architects need to calculate different angle can hold how much weight. Using trigonometric functions, they can solve out the horizontal and vertical components of force, so that the architects can know the capacity of the bridge.

Suspension Bridge

In a suspension bridge, architects still need to consider the capacity of the bridge. However, the shape of suspension bridge is different from Steel Truss Road bridge. The roadway of suspension bridge is actually hanging from large cables. Therefore, the architects must figure out the compression and tension forces that the bridge can hold by using math.

What’s more, the suspension of the bridge is also connected with math. When there is not other weight on the bridge, the cable would form a parabola which can be proved by mathematically.

Arch Bridge

Arch bridge is one of the most oldest types of bridge. Arch bridge is made by one arch, or several arches side by side. By looking at the arch, it is easy to know that, not like other types of bridge, arch bridge is built like a parabolic shape. Using geometry, we can calculate the long and the shape of the bridge.

Besides, in this design, the weight of the bridge is not pushing down directly but spread to the piers on two side.

Conclusion

There are seven different kinds of bridge: the beam, truss, arch, suspension, cantilever, cable-stay and drawbridge. Although they looks different, when building bridges, architects concern about similar problems. Generally, they need to calculate the mass, the carrying capacity, and the shape of bridge by using mathematics. It is easier to build a bridge compared to before because of the math. Not only building bridge, all things in the world are connected with mathematics. Math is changing the world

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This page by Iris D. ('19)

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