Assalam-o-alaikum!
The term 'load bearing structure' is commonly referred to a structure, in which the superstructure loads are transferred to the foundation, through masonry walls. These walls may consist of plain or reinforced masonry. Here are a few good books dealing with design of structural masonry:
1. Manual for Des of Plain Masonry in Building Structures, Institute of Struct Engineers, UK, 1997
2. Design of Structural Masonry by McKenzie, 2001 (BS & Eurocode 6 based)
3. Structural masonry designers’ manual by Curtin et al., 2006 (BS 5628 based)
4. Masonry Structural Design by Klingner, 2010 (IBC 2009 & MSJC-2008 based)
5. Design of Reinforced Masonry Structures by Narendra Taly, 2010 (IBC 2009 & MSJC-2008 based)
Besides, you may find several other resources on the internet, dealing with design of load bearing masonry structures.
Regards.