Steel Angle Bending - Calculating Moment About Principle Axis 1

[CivilSigma]

I am trying to evaluate the moment capacity of an equal leg steel angle using the Canadian S16-19 code.

The code requires you to consider factored bending moments about the principal axis.

I have calculated the factored moment about the geometric axis. But, I need the moment about the principal axis.

I can calculate the angle between the geometric and principal axis.

So, is determining the principal bending moments (about Mx and My) as simple as doing some trig with the angle?

Mx_princ. = Mx_geo. / cos(theta)
My_princ. = Mx_geo. / sin(180-90-theta)

Thank you.

 

[Celt83]

it is a geometric rotation, depending on the rotation direction -Mx*Sin + My*Cos or Mx*Cos + My*Sin : Wikipedia Link


My Personal Open Source Structural Applications:

https://github.com/buddyd16/Structural-Engineering

Open Source Structural GitHub Group:

https://github.com/open-struct-engineer

 

[CivilSigma]

Thank you ! I figured as much (btw my equations are incorrect, thank you for the reference)