Slab base for SC 220, 1000 kN, M30

Assumption: SC 220 (IS 808 column section) is taken as $h=220$ mm, $b_f=220$ mm, $t_f\approx16$ mm. The load of 1000 kN is taken as the factored axial load. Concrete M30 ($f_{ck}=30$), steel Fe410/E250 ($f_y=250$).

1. Bearing strength of concrete (IS 800:2007 cl. 7.4.1)

$0.45f_{ck}=0.45\times30=13.50$ N/mm²

2. Plate size

$$A_{req}=\frac{P}{0.45f_{ck}}=\frac{1000\times10^3}{13.50}=74074\ \text{mm}^2$$

Projection of about 50 mm all round the column (not less than 50 mm): $L=220+2\times50=320$ mm, $B=220+2\times50=320$ mm. Area provided $=102400$ mm² $>A_{req}$ ✓

$$w=\frac{P}{BL}=\frac{1000\times10^3}{320\times320}=9.77\ \text{N/mm}^2<13.50\ \text{N/mm}^2$$

3. Thickness (cl. 7.4.3.1)

Projections $a=50$ mm and $b=50$ mm (larger and smaller):

$$t_s=\sqrt{\frac{2.5w(a^2-0.3b^2)\gamma_{m0}}{f_y}}=\sqrt{\frac{2.5\times9.77\times(50^2-0.3\times50^2)\times1.10}{250}}=13.71\ \text{mm}$$

It must also be not less than the flange thickness $t_f=16$ mm. Provide $t_s=16$ mm.

4. Connections

• The column end is machined to bear on the plate; connect with a nominal 6 mm fillet weld all round (the load is transferred mainly by contact).
• Anchor bolts: 4 nos. M20, embedded about 450 mm with a washer plate (for erection and to resist any uplift).

Answer: base plate 320 × 320 × 16 mm, 4 anchor bolts M20, 6 mm weld, pedestal of M30 concrete.