According to IS: 456-1978, the thickness at the edge in reinforced concrete footings shall not be less than _______ for footings on soils.
- A100 mm
- B150 mmCorrect
- C250 mm
- D350 mm
Solution
Concept
Minimum edge thickness of concrete footings
Formula
NONE
Step-by-step solution
1. IS: 456 specifies minimum edge thickness for reinforced concrete footings to ensure structural integrity and durability. 2. For footings supported directly on soils, the edge thickness shall not be less than 150 mm. 3. For footings on piles, the minimum edge thickness requirement is 300 mm above the top of piles. Answer: B
Explanation
Indian Standard IS 456 specifies minimum structural dimensions to ensure safety and durability at footing edges. For reinforced concrete footings resting directly on soil, the thickness at the edge must not be less than 150 mm. This minimum depth prevents localized shear failures and ensures proper concrete cover.
Why the other options are wrong
A) 100 mm is the minimum edge thickness permitted for footings on piles, not on soil. C) 250 mm exceeds the specified IS code minimum of 150 mm for soil footings. D) 350 mm is greater than the standard minimum edge thickness required by IS 456.
Shortcut
Minimum RC footing edge thickness is 150 mm on soil and 300 mm on piles.
Common mistake
Confusing the minimum edge thickness for footings on soil with the higher thickness required for footings on piles.
Correct answer: B) 150 mm