Moment of Inertia Calculation Guide

1. Choose one of the five frozen section types

TOOL-008 supports Rectangle, Hollow Rectangle, Circle, Hollow Circle, and Doubly Symmetric I-Section only.

2. Enter geometry dimensions

Dimensions may be entered in m, cm, or mm. The UI preserves the same physical geometry when the display unit changes.

3. Read Ix and Iy as the primary results

Ix and Iy are the centroidal-axis second moments of area. They are the primary TOOL-008 outputs.

4. Use Area and Centroid as secondary geometry information

Area and Centroid are inherited from the TOOL-002 Section Properties engine and are presented as secondary outputs.

5. Treat Sx, Sy, rx and ry as read-only Context

These values are inherited from TOOL-002. TOOL-008 does not independently recalculate them and does not promote them to primary results.

6. Apply the frozen Axis Convention

x is the horizontal centroidal axis and y is the vertical centroidal axis. Ix is about the centroidal x-axis and Iy is about the centroidal y-axis.

Rotated axes, principal axes, product of inertia, and arbitrary-axis second moments are outside TOOL-008 V1.

7. Check the I-Section geometry rule

The frozen authoritative rule is webThickness < flangeWidth.

Scope limits

This guide does not cover arbitrary polygons, composite sections, transformed sections, material-strength checks, code-based design verification, utilization, or PASS/FAIL conclusions.