How is 'yield strength' defined in the context of reinforcing steel?

Yield strength in the context of reinforcing steel refers to the point where the material begins to deform plastically. This is a critical characteristic in understanding how steel behaves under load; it indicates the maximum stress that can be applied to the material without permanent deformation. When the stress applied exceeds the yield strength, the steel will undergo irreversible change, leading to permanent deformation.

This property is fundamental in structural engineering and construction applications, as it helps engineers determine the safe working loads for materials being used in construction projects, ensuring safety and integrity. Understanding yield strength allows ironworkers and engineers to make informed choices about reinforcing steel specifications, ensuring structural components can withstand expected loads without failing.

The other choices address different aspects of material behavior. The maximum load a material can sustain pertains to the ultimate tensile strength, while the point of maximum elasticity relates to the elastic limit. The amount of stress before fracture refers to ultimate strength, which occurs after the material has already undergone yielding. Therefore, B accurately captures the definition of yield strength.