What type of forces does a beam primarily resist?

A beam primarily resists flexural and shear forces during its operation. When a load is applied to a beam, it experiences bending, which creates a flexural moment across its length. This bending results in the upper fibers of the beam being in compression while the lower fibers are in tension. However, it's important to note that these tensile and compressive stresses are crucial for understanding the material behavior but are not the primary forces the beam is resisting in a conventional sense.

Simultaneously, beams also experience shear forces due to transverse loads, especially near the supports where the loads are applied. This shear force acts along the cross-section of the beam and can lead to shear failure if not adequately resisted by the design of the beam.

Thus, the combination of flexural (bending) and shear forces characterizes the main types of forces that beams must resist throughout their length and during various loading conditions. Understanding this interaction is critical for ensuring that beams are designed and reinforced appropriately to handle the expected loads and ensure structural integrity.