masonry wall under bending and compression

[aloha]

When checking a bearing wall under lateral bending, why many example book use unity interaction equation: fa/Fa+fb/Fb<=1. rather than (fa+fb)<=(1/3)fm' as specified in 2.3.3.2.2 ACI530-05 for reinforced masonry? I should treat it as unreinforced masonry for a bearing wall? (I do use reinf. For bending)

 

[ARLORD]

That equation is the same as Section 2.3.3.2.2. You have to check both Fb and Fa, per section 2.3.3.2.2.