RC Member Design to IS 456:2000

11 checks fail. Read the advice on the failing member and increase the section on step 3, or reduce the span by adding a bay.

Slab panels

IS 456 Table 26 — restrained two-way slabs

Thickness

125.00mm

Effective depth d

101.00mm

Cover

20.00mm

Table 16

Max moment

5.94kNm/m

Ast required

150.00mm²/m

Ast minimum

150.00mm²/m

Cl. 26.5.2.1

Main steel

8 @ 300mm c/c

Distribution steel

8 @ 300mm c/c

Ast provided

167.55mm²/m

Actual span/d

29.70

Cl. 23.2.1

Allowable span/d

35.78

OKSection is adequate.

Table 26 coefficients αx, αy

Mx negative (support)

5.94kNm/m

Mx positive (mid span)

4.46kNm/m

My negative (support)

4.84kNm/m

My positive (mid span)

3.60kNm/m

Panel A1-B2: lx 3.00 m, ly 3.50 m, β 1.17, two-way, Table 26 case 4.

step by step

1Effective depth d = h − cover − φ/2
= 125 − 20 − 8/2
→ 101 mm
IS 456 Cl. 26.4.2
2Aspect ratio β = ly / lx
= 3.50 / 3.00
→ 1.17 → two-way
IS 456 Cl. 24.4
3Moments M = α · wu · lx²
= αx⁻=0.058, αx⁺=0.043, αy⁻=0.047, αy⁺=0.035; wu=11.44 kN/m², lx=3.00 m
→ Mx⁻=5.94, Mx⁺=4.46, My⁻=4.84, My⁺=3.60 kNm/m
IS 456 Table 26, case 4
4Ast = (0.5 fck/fy)·[1 − √(1 − 4.6 Mu/(fck b d²))]·b·d
= Mu=5.94 kNm/m, fck=25, fy=500, b=1000, d=101
→ 150 mm²/m (min 150)
IS 456 Cl. 38.1 / G-1.1, min Cl. 26.5.2.1
5Spacing s = area of one bar × 1000 / Ast, s ≤ min(3d, 300)
= 50 × 1000 / 150, cap 300
→ φ8 @ 300 mm c/c → Ast prov 168 mm²/m
IS 456 Cl. 26.3.3
6Deflection (l/d) actual ≤ basic × kt
= 29.7 ≤ 20 × 1.79
→ 35.8 → OK
IS 456 Cl. 23.2.1