The maximum dimensions of the core section of a rectangular cross-section (b × d) under eccentric loading on a column are:
Try it first: pick an option, then read the explanation.
Correct answer: D. b/3 and d/3
Asked in SSC JE 2013
Detailed Explanation
The core extends b/6 on either side of the centroid along b and d/6 on either side along d.
Why “b/3 and d/3” Is Correct
Its maximum dimensions (the diagonals) are b/3 and d/3.
Why the Other Options Are Wrong
- A. b/6: b/6 is only the semi-diagonal (max eccentricity) along b.
- B. d/6: d/6 is only the semi-diagonal along d.
- C. d/8: d/8 belongs to a circular section (max eccentricity).
Key Point
Rectangle core: rhombus, diagonals b/3 and d/3; semi-diagonals b/6 and d/6.
Key Concepts for Students
- Middle third in each direction.
- The core is a rhombus, not a rectangle.
- A load on the core boundary gives zero stress at one corner/edge.
Practice more: this is question 36 in Columns and Struts MCQs – Part 3. Try the whole set and check every answer instantly.