How to Calculate Section Properties
1. Define the geometry
Start from a verified section family and define all dimensions using one consistent unit system. For hollow sections, the void is concentric in the current verified scope.
2. Calculate area and centroid
Determine gross geometric area and the centroid location. For the supported symmetric sections, the centroid lies at the geometric center of the bounding geometry.
3. Calculate Ix and Iy
Compute centroidal second moments about the local x and y axes. Hollow sections use outer-minus-inner geometry. The I-section uses flange and web components with the parallel-axis theorem.
4. Derive section modulus
Elastic section modulus is obtained from the centroidal second moment divided by the distance to the extreme fibre.
5. Derive radius of gyration
Radius of gyration is derived from second moment of area and cross-sectional area and is often used in later stability calculations.
6. Interpret the result correctly
Section properties describe geometry. They do not by themselves prove structural capacity, code compliance, buckling resistance, or safety.
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