RCC Design IS 456:2000

Short Span Lx

Long Span Ly

Concrete

Steel

Cover (mm)

Depth

195 mm

Factored Load

13.3 kN/m²

Main Steel

8mm @ 210mm

Long Span

8mm @ 210mm

Ly/Lx = 1.25

1.25 < 2 → Two-way slab (bends in both directions)

d = Lx / (20 × MF) ≈ 4000 / 24

Effective depth d = 170mm, Total depth D = 195mm

Self-weight = 195×25/1000 = 4.88 kN/m² DL (total) = 6.88 kN/m², LL = 2 kN/m² wu = 1.5 × (6.88 + 2) = 13.31 kN/m²

Factored load wu = 13.31 kN/m²

Mux = αx × wu × Lx² = 0.056 × 13.31 × 4.00² Muy = αy × wu × Lx² = 0.056 × 13.31 × 4.00²

Mux = 11.93 kN·m/m (short span) Muy = 11.93 kN·m/m (long span)

Mu,lim = 0.36 × fck × xu,max/d × (1 - 0.42 × xu,max/d) × b × d²

Mu,lim = 96.53 kN·m/m. Mu = 11.93 < Mu,lim ✓ Singly reinforced

Ast = (fck×b×d)/(2×0.87×fy) × [1 - √(1 - 4.6Mu/(fck×b×d²))]

Short span: 8mm @ 210mm c/c (Ast = 239 mm²/m) Long span: 8mm @ 210mm c/c (Ast = 239 mm²/m)

Actual L/d = 4000/170 = 23.5 Allowed L/d = 20 × 1.6 = 32.0

23.5 ≤ 32.0 ✓ OK