Built-up Section Calculator
Calculate area, mass, centroid, second moments of area, section moduli, radii of gyration and surface area of welded and built-up plate sections. Export the result as section XML.
Result – Welded H
Area A25,600mm²
Mass per metre200.96kg/m
Centroid (from bottom-left)200.0 / 200.0mm (x̄ / ȳ)
| Parameter | x-axis | y-axis | Unit |
|---|---|---|---|
| Second moment of area I | 761.333 | 266.786 | 10⁶ mm⁴ |
| Elastic section modulus Z (min) | 3,806.7 | 1,333.9 | 10³ mm³ |
| Elastic section modulus Z (top/right) | 3,806.7 | 1,333.9 | 10³ mm³ |
| Elastic section modulus Z (bottom/left) | 3,806.7 | 1,333.9 | 10³ mm³ |
| Plastic section modulus S | 4,240.0 | 2,022.4 | 10³ mm³ |
| Radius of gyration r | 172.5 | 102.1 | mm |
| Principal I1 / I2 | 761.333 | 266.786 | 10⁶ mm⁴ |
| Torsion constant JOpen thin-walled approximation Σ b·t³/3 | 4,644.5 | 10³ mm⁴ | |
| External surface area | 2.368 | m²/m | |
| Overall depth × width | 400.0 × 400.0 | mm | |
Method & assumptions
A = Σ Ai ; ȳ = Σ Ai·yi / A ; Ix = Σ (Ix,i + Ai·(yi − ȳ)²) ; Z = I / ymax ; r = √(I / A)
Plates are treated as perfectly joined rectangles; weld metal and corner rounding are neglected.
Plastic modulus S is found numerically from the equal-area axis. Local buckling, effective sections and weld design are outside the scope of this calculator.