Basic shapes and axes
Section geometry
Inputs
Basic closed forms with centroidal horizontal axis.
For circle/tube, enter outer diameter here.
Used for rectangle only.
Results
Cross-sectional areaA
7,200
Second moment of areaI
8,640,000
Section modulusS
144,000
mm³A = bh; Iₓ = bh³ / 12; Sₓ = Iₓ / (h/2)
A first-pass number, not a code check, certification, or approval. Read the method and its limits below. What this is and is not.
Nearby: Right-triangle frame · 3D coordinate span · Cylinder geometry · Circular arc & segment
Method
Formula, when it applies, and when it does not
Resolve geometric properties for a small set of explicitly diagrammed cross-sections.
A = bh; Iₓ = bh³ / 12; Sₓ = Iₓ / (h/2)
When
- Named reference axes
- Positive geometry
Don’t
- Geometry values are calculated about the displayed centroidal horizontal axis. Verify the chosen axis and that the basic shape represents the actual section.
Roark's Formulas for Stress and Strain — section properties