Rebars for slabs & walls — mixed diameters
Cross-sectional area per 1 m for alternating bar pairs (Ø d₁ / Ø d₂) at given spacing
A = (100 / s) / 2 · π · Ø₁² / 4 + (100 / s) / 2 · π · Ø₂² / 4 [cm²/m]
Two diameters alternate at spacing s [cm], so each diameter appears every 2·s and contributes (100/s)/2 bars per metre. Rows with spacing that is a multiple of 5 cm (30, 25, 20, 15, 10, 5) are highlighted. Ø₁, Ø₂ — bar diameters [mm].