Which structural form is typically least resistant to bending?

The structural form that is typically least resistant to bending is a long beam. This is primarily due to its increased length, which magnifies the effects of bending moments and deflections. As the length of a beam increases, it becomes more susceptible to bending forces. The bending resistance of a beam is influenced by both its material properties and its geometry; longer beams often experience greater stress and strain due to bending loads because they have a larger moment arm for any applied force.

In contrast, shorter beams can distribute loads more efficiently, maintaining higher rigidity and minimizing deflection under similar loads. Furthermore, different cross-sectional shapes, such as rectangular and circular beams, can also play a significant role in resisting bending. Generally, circular beams tend to offer better resistance due to their uniform distribution of material around the axis and higher moment of inertia, whereas rectangular beams, while better than long beams, may still experience significant bending.