Mechanics

Interactive section builder

Build composite sections from rectangles, circles, polygons and voids, then compute geometric section properties.

Interactive section builder

Project settings

Edit unit

Convention: positive X to the right, positive Y upward, positive rotation counter-clockwise.

Profile presets

PresetMaterial

Outer width B [mm]Outer height H [mm]Wall thickness t [mm]

Examples

Parts list

Add the first section part or load an example to calculate area, centroid and second moments of area.

Materials

Add from Material Database

Reference material

Structural steel — ASTM A36

NameDensity [kg/m³]Young's modulus E [GPa]Yield strength fy [MPa]Ultimate tensile strength fu [MPa]Source typeSourceSource note

Aluminium 6061-T6

NameDensity [kg/m³]Young's modulus E [GPa]Yield strength fy [MPa]Ultimate tensile strength fu [MPa]Source typeSourceSource note

Concrete

NameDensity [kg/m³]Young's modulus E [GPa]Yield strength fy [MPa]Ultimate tensile strength fu [MPa]Source typeSourceSource note

Older files without fy, fu and material-source fields import without invented values.

Workspace

solid partvoid — dashed lineprincipal axes — dashed lines

Bending preview

Statusnot evaluated

Load modeAxis and section sideMoment [kN·m]Safety factor

Inputs used

Material

Selected W—cm³

Absolute moment—kN·m

Entered moment sign—kN·m

Stress σ = M/W—MPa

Preview results

Yield strength fy—MPa

Allowable stress—MPa

Yield moment My—kN·m

Allowable moment M_allow—kN·m

Model utilization—

Required section modulus W_req—cm³

Section modulus reserve—cm³

Allowable force F_allow—kN

Add the first section part or load an example to calculate area, centroid and second moments of area.

Import / export project

Export

Model assumptions and limitations

The tool determines idealized geometric properties; current-model problems remain visible with diagnostics.

Positive parts may touch at edges but may not overlap in area. Voids must remain strictly inside their parent part.
Material values are copied once from documented database records or user input; they are not an automatic code-design basis.
The transformed section assumes linear-elastic full composite action through Young's-modulus ratios.
The bending preview is not a beam solver and does not calculate reactions, internal-force diagrams or deformation.
No local/global buckling, lateral-torsional buckling, torsion, shear-center or plastic-capacity check.
No weld, notch, stress-concentration, damage, corrosion, fatigue, temperature or code check.
Jp = Ix + Iy. For non-circular sections it is not the general Saint-Venant torsion constant.

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Related calculators

Rectangle area moment of inertia Circle area moment of inertia Tube area moment of inertia Rectangle section modulus Principal area moments

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Interactive section builder