Solution: Two-way Slab Design

1.1 Effective Depth

• Assume slab thickness = 180mm
• Effective depth (d) = 180 - 20 - 6 = 154mm

1.2 Loading

• Self weight = 0.18 × 25 = 4.5 kN/m²
• Floor finish = 1.0 kN/m²
• Live load = 4.0 kN/m²
• Total load = 9.5 kN/m²
• Factored load = 1.5 × 9.5 = 14.25 kN/m²

2.1 Bending Moments (IS 456 Table 26)

• Short span moment = αx × wu × lx²
• αx = 0.045 (for two adjacent edges discontinuous)
• Short span moment = 0.045 × 14.25 × 3.5² = 7.85 kN⋅m/m
• Long span moment = αy × wu × lx²
• αy = 0.032
• Long span moment = 0.032 × 14.25 × 3.5² = 5.58 kN⋅m/m

3.1 Flexural Reinforcement (Short Span)

• Mu = 7.85 kN⋅m/m
• d = 154mm
• Required As = 145 mm²/m
• Provide 10mm @ 200mm c/c (393 mm²/m)

3.2 Flexural Reinforcement (Long Span)

• Mu = 5.58 kN⋅m/m
• d = 154mm
• Required As = 103 mm²/m
• Provide 8mm @ 200mm c/c (251 mm²/m)