A slab having total thickness 120 mm is provided reinforcement bars of following diameters. The permissible diameter is
- A15 mmCorrect
- B16 mm
- C18 mm
- D19 mm
Solution
Concept
Maximum diameter of reinforcement (IS 456 cl. 26.5.2.2)
Formula
φmax ≤ D / 8
Step-by-step solution
1. φmax = 120 / 8 = 15 mm.
Explanation
IS 456 limits the diameter of bars in a slab to one-eighth of the total thickness.
Why the other options are wrong
16, 18 and 19 mm exceed D/8 = 15 mm.
Shortcut
Bar diameter ≤ D/8.
Common mistake
Using D/6.
Correct answer: A) 15 mm