Section Properties
🏗️ Civil · Area, moment of inertia, section modulus, and radius of gyration — 4 section types
A cross-section’s geometric properties directly determine its bending and buckling behavior. Four fundamental properties are calculated:
- Area (A): relates to axial load-carrying capacity.
- Moment of inertia (I): determines bending stiffness — the farther material is moved from the axis, the larger I grows.
- Section modulus (W = I/c): directly related to bending strength (σ = M/W).
- Radius of gyration (r = √(I/A)): an indicator of buckling resistance.
This tool supports four common section types: rectangle, circle, tube (hollow circle), and I-beam.
Why do beams have an I cross-section? For the same amount of material (same area), placing material as far as possible from the neutral axis increases the moment of inertia. The I-profile applies this principle optimally: most of the material is concentrated in the top and bottom flanges (where bending stress is highest), while the web is kept thin since it mainly carries shear force. This gives a much higher bending stiffness than a rectangular section of the same weight.
This tool's calculation logic has been checked against a hand-computed numerical verification test. Test source: src/lib/calc/kesit.test.ts.
- [2] Hibbeler, R. C.. Mechanics of Materials, 10 ed.. Pearson, 2017. ↗
Section Properties — EngineersLab calc card
Formula: I = bh³/12 (rectangle), I = πd⁴/64 (circle)
Sources: [2] Mechanics of Materials
Tool version: 1.0.0 · Date:
Source URL: https://engineerslab.com.tr/en/araclar/kesit
Results are for educational and preliminary-sizing purposes; final engineering design decisions must reference the relevant standards and a licensed engineer's approval.