Slenderness Ratio
According to CLT Handbook, Chapter 8, Section 4.1.4.1, Equation 16 the radius of gyration for calculating the slenderness ratio for CLT panels = √ (I/A), so the slenderness ratio is
Ieff and Aeff are calculated using the longitudinal layers only.
Column Stability Factor CP
Chapter 8, Section 4.1.4.1, Equation 16 gives the CLT formula for the Stability Factor CP also given in NDS C3.7.1.4 - Alternative Stability Factor for CLT Wall Panels.
Combined Axial and Bending
Chapter 8,Section 4.1.4.1, Equation 18 gives the alternative formula for CLT combined axial and bending design also given in NDS C15.4 - CLT Combined Axial and Bending :
Fire Design
For axial fire design assumptions, refer to Axial CLT Fire Design