Which of the following stresses is used for identifying the quality of structural steel? A. Ultimate stress B. Yield stress C. Proof stress D. None of the above

The correct answer is: B. Yield stress

The yield stress is the stress at which a material begins to deform permanently. It is a measure of the material’s strength and is used to identify the quality of structural steel.

The ultimate stress is the stress at which a material fails. It is a measure of the material’s toughness and is not used to identify the quality of structural steel.

The proof stress is a stress that is lower than the yield stress. It is used to determine the yield strength of a material in the presence of residual stresses.

None of the above is the correct answer.