huangyhg

wood trusses as conc/mas wall out-of-plane anchorage
my question is regarding the use of wood trusses as out-of-plane wall anchorage for concrete and masonry walls.
the problem arises when i read section 1633.2.8.1, paragraph 5, of the 2001 cbc. it clearly states in this section that when using a wood member, in conjunction with a flexible diaphragm (wood trusses with plywood sheathing), in seismic zones 3 and 4, the wood member shall have a minimum actual net thickness of 2 1/2". this mandates the use of a 3x truss. most every contractor and every truss manufacture that bids this combination of trusses and cmu walls, states that the 3x trusses are not needed and are out of the ordinary.
questions: am i reading this correctly? is there an "out" somewhere in the wood chapter, chapter 23, that i am not aware of? what is everyone else out there doing when using wood trusses to anchor wall-out-of plane forces from concrete and masonry walls?
a prompt reply will be appreciated. thank you.
the section you refer to states that "wood elements of the wall anchorage system" shall have a 2.5" min thickness. i interpret this as requiring a 3x plate at cmu walls supported by a wood diaphragm. this is not at all unusual in california.
otherwise, if you keep expanding your definition of "wall anchorage system", you will end up with a 2.5" thick timber diaphragm...

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