Question

Which of the following factors is included in the limit state of strength?

• A. Fire
• B. Failure by excessive deformation
• C. Corrosion
• D. Repairable damage or crack due to fatigue

Hint:

Strength limit state is about {safety against collapse}. Serviceability is about {comfort/appearance} (deflection, cracking) without collapse.

Answer 1

The Correct Option is B

Step 1: Understand what “limit state of strength” means.
Limit state of strength refers to a condition related to collapse or failure of the structure, where the structure becomes unsafe.
It includes failures such as yielding, buckling, fracture, instability, or deformation leading to loss of load carrying capacity.
Step 2: Check each option with respect to strength (collapse) criteria.
(A) Fire: Fire is generally treated as an accidental/exceptional loading condition, not a normal strength limit state factor.
(B) Failure by excessive deformation: If deformation becomes excessive such that the member loses stability or load capacity, it is treated under strength/collapse considerations. Hence, this is the best match.
(C) Corrosion: Corrosion is mainly a durability issue and affects long-term performance, not directly a strength limit state factor in standard MCQ classification.
(D) Repairable damage or crack due to fatigue: Fatigue cracking is usually treated under fatigue/durability or service life criteria and is not taken as the primary “strength limit state” factor in such MCQs.
Step 3: Conclusion.
Therefore, the factor included in the limit state of strength (collapse-type consideration) is (B) Failure by excessive deformation.