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 – Built-up Channel
Area A7,520mm²
Mass per metre59.03kg/m
Centroid (from bottom-left)33.1 / 200.0mm (x̄ / ȳ)
| Parameter | x-axis | y-axis | Unit |
|---|---|---|---|
| Second moment of area I | 183.170 | 10.323 | 10⁶ mm⁴ |
| Elastic section modulus Z (min) | 915.8 | 118.8 | 10³ mm³ |
| Elastic section modulus Z (top/right) | 915.8 | 118.8 | 10³ mm³ |
| Elastic section modulus Z (bottom/left) | 915.8 | 312.0 | 10³ mm³ |
| Plastic section modulus S | 1,075.8 | 213.5 | 10³ mm³ |
| Radius of gyration r | 156.1 | 37.1 | mm |
| Principal I1 / I2 | 183.170 | 10.323 | 10⁶ mm⁴ |
| Torsion constant JOpen thin-walled approximation Σ b·t³/3 | 433.7 | 10³ mm⁴ | |
| External surface area | 1.260 | m²/m | |
| Overall depth × width | 400.0 × 120.0 | 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.