A structure's strength is derived from its shape and the materials it is constructed from. The strength of a structure is its capacity to withstand the forces that tend to break the structure or change its shape, according to PBS Learning Media. A triangle is considered the strongest structural shape. In the case of a triangular building, collapse occurs only due to material fatigue and not geometrical distortion.
Square and rectangular buildings or structures can collapse due to geometrical distortion when forces such as high winds act upon the structure, notes Reference.com. For this reason, triangles are the building blocks of many man-made structures. PBS Learning Media cites other geometrical shapes that add to the strength of a structure, such as arches and domes. These shapes can be seen prominently in bridges and large buildings. For example, arches utilize compression to strengthen bridges, while domes excel at bearing weight.
Compression is the inward pull of a structure and is opposed to the tension of a structure, which is its tendency to pull outward. Compression and tension are additional components of a building's strength. Compression and tension are what cause skyscrapers to sway slightly. A structure's strength differs from its stability. Stability is a structure's ability to maintain balance.