The Steel Section Properties Calculator looks up cross-sectional properties for Indian rolled steel sections — ISMB (medium beams), ISWB (wide-flange), ISHB (heavy-duty), ISLB (light), ISMC (channels), ISJC (joist channels), ISA (angles), ISLC (light channels) — per IS 808:1989. Output includes area, depth, flange/web thickness, moment of inertia (Ixx, Iyy), section modulus (Zxx, Zyy), radius of gyration, and weight per metre.
Use it during preliminary structural sizing, when reading existing drawings to confirm a tagged section, or as a quick reference during design verification. The values match those in IS 808 Table 1 and Annex A within tolerance.
Per IS 808:1989, sections are designated by the series letter and nominal depth in mm: ISMB 250 = Indian Standard Medium Beam, 250 mm depth. ISMB ranges 100-600 mm; ISWB 150-600 mm; ISHB 150-450 mm; ISMC 75-400 mm. Heavier variants suffixed with weight-grade letter (e.g., ISHB 200H is the heavier version at the same depth). Always cross-check with IS 808 Table 1 if the drawing's section letter is unclear.
For flexural design (IS 800 Cl. 8.2): use Zxx (plastic or elastic section modulus depending on plastic or elastic design method) for major-axis bending; Zyy for minor-axis. For shear (Cl. 8.4): web area = (D − 2T_f) × t_w, capacity 0.6 × f_y × A_v / γ_m0. For axial compression (Cl. 7): use minimum radius of gyration r_min = √(I_min / A) to compute slenderness ratio λ = Le / r_min. Effective length factor Le depends on end conditions (Cl. 7.2.2 Table 11).
Nominal IS 808 properties differ from IS 1852 cross-section tolerances by ±2-3% on area and ±5% on outer dimensions. For competition design (composite, hot-rolled vs welded), refer to actual mill test certificates. For routine RCC + steel residential / commercial design, IS 808 nominal values are used directly.
Total load: 25 × 6 = 150 kN. Max moment (UDL): wL²/8 = 25 × 36 / 8 = 112.5 kN·m. For Fe 410 (f_y = 250 N/mm²), required Zxx = M / (f_y / γ_m0) × γ_m0 = 112.5 × 10⁶ / (250 / 1.10) = 495 × 10³ mm³ = 495 cm³. From IS 808: ISMB 300 has Zxx = 573 cm³ — adequate. Lighter ISMB 275 has Zxx = 477 cm³ — marginal. Pick ISMB 300 (44.2 kg/m). Check shear: V_max = 75 kN, A_v = (300 − 2×7.6) × 7.5 = 2,138 mm², capacity 0.6 × 250 × 2,138 / 1.10 = 291 kN >> 75 kN OK. Check deflection: δ_max = 5wL⁴/(384 EI) — see IS 800 Cl. 5.6.1 for serviceability limits.
ISMB (Medium Beam): standard-section-depth I-beam, narrow flange, used for general light-to-moderate flexure. ISWB (Wide-flange Beam): same depth but wider flange — better lateral-torsional buckling resistance, preferred for longer spans or wind-exposed structures. ISHB (Heavy-duty Beam): same flange width as ISWB but thicker web and flanges — used for heavy axial load + flexure (column-like beams). For pure axial column use, ISHB or built-up sections are typical.
W = ρ × A where ρ is steel density (7,850 kg/m³ ≈ 7.85 × 10⁻⁶ kg/mm³) and A is cross-section area in mm². For nominal IS 808 sections, the calculator simply reads from Table 1. For arbitrary cross-sections, compute area first.
I_xx is the moment of inertia about the horizontal (strong) axis through the centroid — used when bending about the strong axis (typical floor beams). I_yy is about the vertical (weak) axis — relevant for biaxial bending (column under wind), or for sections used flat (channels as purlins).
No. IS 808 covers rolled sections only. For welded built-up sections (deep girders, plate girders), compute I and Z from first principles using parallel-axis theorem on the constituent plates, then apply IS 800 Cl. 8.2.2 / Cl. 8.5 for plate-girder design checks (web shear buckling, flange compactness).
Plastic section modulus Z_p is the property used in IS 800 Limit State design — it represents the moment capacity at full plastic yield (entire cross-section yielded in tension or compression). Z_p > Z_e (elastic) by the shape factor ~1.10-1.15 for I-sections. For plastic design (IS 800 Cl. 8.2.1.2 a), only Class 1 and Class 2 sections (compact) can use Z_p.