Angle Section Properties

Like many others, I discovered through experience that the principal axis section modulus values for angles provided in the 13th Edition AISC manual are incorrect. While the principal axes moment of inertia values are accurate, the 'c' value used to calculate the section modulus was consistently incorrect. To address this and provide more comprehensive information, Version 2.0 now includes the following enhancements:

1. Angle Leg Orientation: The worksheet now allows you to specify the orientation of the angle legs and subsequently calculate the section properties about this modified axis orientation. The configurations addressed include:

   • SLVD: Unequal leg - short leg vertically down
   • SLVU: Unequal leg - short leg vertically up
   • LLVD: Unequal leg - long leg vertically down
   • LLVU: Unequal leg - long leg vertically up
   • EQVLD: Equal leg - long leg vertically down
   • EQVLU: Equal leg - long leg vertically up

2. Beta w Factor Calculation: The worksheet now includes the calculation of the Beta w factor, which is used in the 13th Edition AISC Manual - equation F10-6 for calculating allowable moments about the major principal axis for unequal length angles. The correct sign of Beta w, which depends on whether the shear center is in flexural compression or tension, is also calculated.

3. Torsional Resistance Factor (J) Calculation: The worksheet now calculates the torsional resistance factor, J.

4. Extreme Fiber Distances Calculation: The worksheet now calculates the distances from the neutral axis to all angle tip points.

Please note that while the worksheet is protected, it does not require a password.

Calculation Reference

AISC 13th Edition

Modern Formulas for Statics and Dynamics

Structural Steel Designer's Handbook