Test: RCC Design- 3 - Civil Engineering (CE) MCQ

As per IS 456:2000, Clause 5.3.3.1:

For Heavily reinforced concrete members as in the case of ribs of main beams, the nominal maximum size of aggregate should usually be restricted to 5 mm less than the minimum clear distance between the main bars or 5 mm less than the minimum cover to the reinforcement whichever is smaller.

Theoretical value = 0.70 L

Recommended value = 0.80 L

As per IS 456 : 2000 Clause number 26.4,

For nominal reinforcement.

For footings, minimum cover shall be 50 mm.

For a longitudinal reinforcing bar in a column nominal cover shall in any case not be less than 40 mm, or less than the diameter of such bar.

In the case of columns of minimum dimension of 200 mm or under, whose reinforcing bars do not exceed 12 mm, a nominal cover of 25 mm may be used.

The horizontal distance between parallel main reinforcement bars shall not be more than three times the effective depth of solid slab or 300 mm whichever is smaller. The total reinforcement in the slab should remain same. By replacing 10 mm bars by 16 mm bars, the spacing will increase as

As per IS 456:2000, minimum eccentricity equals to unsupported length of column/500 plus lateral dimension/30, subject to minimum of 20 mm.

In this case:  along shorter side

And mm along longer side.

f_ck = 20 MPa

D = 700 mm

q_o = 7 Mpa



∴ tan⁡ α = 700/L ⇒ L = 129.6 ≃ 130mm

Area of footing = 2 × 3 = 6m²

Section modulus,

From (i) and (ii), we get

⇒ M = 60 kNm

P_u = 1.5 × 2500 = 3750 kN

A = 460 × 460 = 211600 mm²

P_u = 0.4 f_ck A_c + 0.67 f_y A_sc

3750 × 10³ = 0.4 × 20 × (211600 - A_sc) + 0.67 × 415 A_sc

A_sc = 7618 mm² 

The critical section for bending moment is the face of the column:-
P_o = Net upward pressure = 1.5 N/mm²