The structural device that supports vertical loads by transforming them into axial forces is called which of the following?

• A. A cantilever
• B. An arch
• C. A post-and-beam system
• D. An arch (structure)

Answer: (B)

An arch carries loads primarily through compression along its curved shape. When vertical loads are applied to the arch, the geometry directs those forces as axial forces along the arch, creating a compressive path that pushes outward at the supports. This arch action transforms vertical gravity into axial forces, allowing a generous span with relatively little material. The supports must resist the outward thrust, which is a key feature of arches.

In contrast, a cantilever relies on bending of a fixed-ended beam to resist loads, not primarily on axial compression along a curved path. A post-and-beam system transfers loads through a frame of columns and beams, with bending, shear, and some axial components, rather than the main action being arch-like compression. Therefore, the term that best describes transforming vertical loads into axial forces is the arch.