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StructuralEngineerLab · TOOL-002

Section Properties Calculator

Calculate area, centroid, centroidal second moments of area, elastic section modulus, and radii of gyration for five standard symmetric sections.

Section input

Length unit
Ready.

Results

Result units: canonical SI — m, m², m³ and m⁴. Input units may be mm, cm or m.

Enter section dimensions and calculate to see engineering properties.

Assumptions

  • All dimensions are positive and converted to canonical SI before calculation.
  • Hollow rectangle and hollow circle are concentric.
  • I-section is doubly symmetric with equal top and bottom flanges.
  • Ix and Iy are centroidal second moments about the local section axes.

Limitations & warnings

  • No rotated or principal-axis transformation.
  • No plastic section modulus, torsion constant, warping constant, or code design.
  • Results are geometric properties, not a structural capacity check.

Method & assumptions

This calculator evaluates geometric properties for five verified symmetric section families. Dimensions are normalized to canonical SI before calculation, while the user interface can accept millimetres, centimetres, or metres.

  • All dimensions are positive and finite.
  • Hollow rectangle and hollow circle are concentric.
  • The I-section is doubly symmetric with equal top and bottom flanges.
  • Ix and Iy are centroidal second moments about the local section axes.
  • Input dimensions are normalized to canonical SI before calculation.

Limitations

  • No arbitrary polygon or user-drawn section.
  • No rotated/principal-axis transformation.
  • No plastic section modulus.
  • No torsion constant or warping constant.
  • No structural capacity or code-based design verification.

These are geometric properties only and should not be interpreted as a structural safety or code-compliance result.

Worked example: 300 × 150 × 20 × 10 mm I-section

Use an I-section with overall depth 300 mm, flange width 150 mm, flange thickness 20 mm, and web thickness 10 mm. The calculator converts each input to canonical SI, calculates the composite area and centroid, then evaluates Ix and Iy using flange/web component formulas and the parallel-axis theorem. Sx, Sy, rx, and ry are derived from the verified section properties.

Use the Load example button in the calculator to reproduce the same geometry.

Frequently asked questions

What does the Section Properties Calculator calculate?

It calculates geometric section properties including area, centroid, Ix, Iy, elastic section modulus Sx and Sy, and radii of gyration rx and ry for five standard symmetric section shapes.

Which section shapes are supported?

The current verified version supports rectangle, concentric hollow rectangle, circle, concentric hollow circle, and doubly symmetric I-section geometry.

What units are used for results?

Inputs can be entered in millimetres, centimetres, or metres. The calculation engine normalizes dimensions to canonical SI and reports results in m, m², m³, and m⁴.

Does this calculator check structural capacity or code compliance?

No. The tool calculates geometric section properties only. It does not perform strength design, code compliance checks, buckling design, torsion design, or structural capacity verification.

How is the I-section moment of inertia calculated?

The verified engine calculates the doubly symmetric I-section from flange and web components and applies the parallel-axis theorem for the centroidal x-axis.

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