Shallow Foundations MCQ with answer and solution

Concept

IS 456:2000 gives a minimum thickness at the edge of a footing: 150 mm for footings on soil and 300 mm above the top of piles for footings on piles.

Step-by-step solution

1. Recall the IS 456:2000 rule for footings. 2. The edge thickness must not be less than 150 mm for footings on soils. 3. For footings on piles, it must not be less than 300 mm above the top of piles. 4. So the answer is 150 mm, option C.

Explanation

IS 456:2000 fixes a minimum edge thickness so the footing edge is strong enough and the steel gets proper cover. For footings resting on soil, this minimum is 150 mm. For footings on piles, the limit is 300 mm above the pile top.

Why the other options are wrong

A (120 mm), B (125 mm) and D (100 mm) are all less than the code limit of 150 mm.

Shortcut

Remember 150 / 300: 150 mm on soil, 300 mm on piles.

Common mistake

Mixing up the footing edge limit with the minimum cover or the minimum slab thickness values.