Question

A student asks why triangles often appear in structures such as bridges, building frames, and trusses. How do you respond?

Answer 1

Triangles have been used extensively in construction due to their rigid shape and strength.

Due to the rigidness of the triangle's shapes, high amounts of forces can be sustained without deformation. Triangles are often used as trusses in bridges, or other support structures in buildings. They can easily be fit together to provide strength and stability over a wide area

A triangle is stable. If all of the joints in a frame are pins, so that they can turn freely, a triangle will retain its shape, while anything with more sides will not - imagine a square frame, you can simply squish it by its corners.

The design behind structures that make use of triangles has a basic assumption that all of the joints act as pins and can rotate, requiring them to be made of stable shapes.

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