Steel Sections Inertia Calculator
Calculate section properties for structural steel elements. Choose between I-Beams, C-Channels, Z-Sections, Rectangular Hollow Sections (RHS), and Square Hollow Sections (SHS) to find Moments of Inertia, Section Moduli, and Radii of Gyration.
Section Shape & Dimensions
Section Properties
| Cross-sectional Area (A) | -- |
| Inertia X-Axis (Ix) | -- |
| Inertia Y-Axis (Iy) | -- |
| Section Modulus (Sx) | -- |
| Section Modulus (Sy) | -- |
| Radius of Gyration (rx) | -- |
| Radius of Gyration (ry) | -- |
Steel Sections Structural Formulas
• Hollow RHS Section: Outer $B\times H$, Inner $b=B-2t$, $h=H-2t$. Ix = (B·H³ - b·h³) ÷ 12 | Iy = (H·B³ - h·b³) ÷ 12
• I-Beam Section: Flange $B$, Web thickness $tw$, total height $H$, flange thickness $tf$, inside height $h=H-2tf$. Ix = [B·H³ - (B - tw)·h³] ÷ 12 | Iy = (2·tf·B³ + h·tw³) ÷ 12
• C-Channel Section: Flange B, Web thickness tw, total height H, flange thickness tf. Centroid offset Xcg is computed relative to back of web, and Y-axis Inertia is calculated using the Parallel Axis Theorem: Iy = [h·tw³/12 + h·tw(X_cg - tw/2)²] + 2[tf·B³/12 + B·tf(X_cg - B/2)²]
• Other properties: Modulus S = I ÷ ymax, Gyration r = √(I ÷ A). All units are expressed in standard metric format: Area in mm², Inertia in mm⁴ (and scaled to cm⁴ for engineering usability), Section Modulus in cm³, Radius of Gyration in mm.
How to use Steel Sections Inertia Calculator
- Select the steel section type: I-Beam, C-Channel, Z-Section, RHS/SHS, or Circular.
- Enter the section dimensions: flange width, flange thickness, web height, web thickness, or wall thickness.
- Click Calculate to view structural area, centroid, moments of inertia, section moduli, and radius of gyration.
What is Steel Sections Inertia Calculator?
In structural engineering, the cross-sectional shape of a beam determines its load capacity and resistance to bending and deflection. Key design parameters include the Cross-sectional Area ($A$), Moment of Inertia ($I_x, I_y$ which determine bending resistance), and Section Modulus ($S_x, S_y$ which determine bending stress limits).
This calculator computes these exact engineering properties for five common steel profile geometries. It is an essential tool for civil and mechanical engineers designing structural beams, columns, and purlins.
FAQ
- What is the Moment of Inertia?
- The Moment of Inertia (I) measures a shape's resistance to rotational bending around a specific axis. A higher Moment of Inertia means the beam will deflect less under a given load.
- What is the Section Modulus?
- The Section Modulus (S) is the ratio of the Moment of Inertia to the distance from the neutral axis to the outermost fiber. It is used to calculate the maximum bending stress in a beam under load (Stress = Moment / S).
- How does a hollow section compare to a solid section?
- Hollow sections (RHS/SHS) place material far from the neutral axis, giving them excellent strength-to-weight ratios and high torsional resistance compared to solid bars of similar weight.
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