Consider the following statements regarding the behavior of a column under a compression load : 1. The stress-strain properties do not remain constant throughout the section. 2. Residual stresses due to cooling after rolling the steel section and those imposed by welding during construction exist in the section before loading. 3. Due to construction details, the load is perfectly concentric and the end conditions will not vary from case to case. Which of the above statements is/are correct ?
- A1 and 2Correct
- B1 only
- C2 only
- D1 and 3
Solution
Concept
Imperfections in real columns
Step-by-step solution
1. Material properties vary across the section (true). 2. Residual stresses from rolling and welding are present before loading (true). 3. In practice loads are never perfectly concentric and end conditions vary from case to case (false).
Explanation
Real columns have residual stresses, varying yield strength, initial crookedness and accidental eccentricities.
Why the other options are wrong
Statement 3 describes an ideal column.
Shortcut
Real column = imperfect.
Common mistake
Assuming ideal conditions.
Correct answer: A) 1 and 2