Section Modulus Calculation Guide

1. Choose one of the five frozen section types

TOOL-009 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 Sx and Sy as the primary results

Sx and Sy are elastic geometric section modulus values about the centroidal x and y axes.

4. Treat other section properties as read-only Context

Ix, Iy, Area, Centroid, rx and ry are inherited directly from TOOL-002 and are not independently recalculated by TOOL-009.

5. Apply the frozen Axis Convention

x is the horizontal centroidal axis and y is the vertical centroidal axis. Sx corresponds to the centroidal x-axis and Sy to the centroidal y-axis.

Rotated axes, principal axes, arbitrary-axis section modulus and product-of-inertia-based transformations are outside TOOL-009 V1.

6. Understand Extreme-Fiber Distance ownership

Extreme-fiber distance semantics are owned by TOOL-002. TOOL-009 does not accept or modify cx/cy and does not recalculate those distances.

TOOL-009 V1 provides Elastic Geometric Section Modulus only. Plastic Section Modulus is outside scope.

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, Plastic Section Modulus, material-strength checks, code-based design verification, utilization, or PASS/FAIL conclusions.