Cp for stud wall members

[conradlovejoy]

Somewhat new to wood framing design so I apologize in advance if this is an elementary question. I am attempting to calculate the combination load effects for a stud wall with sheathing on both faces (exterior plywood sheathing and interior gyp-board) and would like to know if the column stability factor, C_p, should be calculated using Eqn. 3.7-1 in the NDS or if it should just be 1.0 (considered supported throughout its length to prevent lateral displacement). My thought is that the sheathing doesn't necessarily prevent bending in the strong axis, but only prevents lateral movement or buckling in the weak axis but I want to be sure that is a correct assumption because the C_p value can make a big difference in the final F'_c value. Thank you.

 

[JAE]

We typically assume that in the strong axis bending of the stud the sheathing does nothing except laterally brace the stud. Some designers will utilize the composite action of the sheathing with the stud but we don't.