What does shear strength in concrete refer to?

Shear strength in concrete specifically refers to the capacity of a concrete member to resist sliding failure along a plane, particularly under the action of shear forces. When shear forces are applied, they attempt to cause one part of a concrete structure to slide over another. Shear strength is crucial for the stability and integrity of concrete structures, especially in situations where forces act parallel to the material's cross-section, such as in beams, slabs, and columns.

Understanding shear strength is essential for structural engineers as it helps in the design and assessment of concrete components, ensuring they can effectively carry the anticipated loads without experiencing shear failure, which could lead to significant structural issues. The other options, while relating to different properties of concrete, do not accurately describe shear strength. For instance, bending forces relate to flexural strength, thermal expansion pertains to temperature-related expansion properties, and fatigue resistance concerns the material's ability to withstand cyclic loading. All of these are important, but they are distinctly different from shear strength.