I’m trying to understand if alternate braced walls are permitted in SDC 'D' in the 2006 IBC and have two questions.

Question 1: Footnote “a” of Table 2308.12.4 requires that the bracing have a h/w ratio not exceeding 2:1, so are the alternates per Section 2308.9.3.1 and 2308.9.3.2 permitted?

Answer 1: Yes. That footnote originated in the 1997 NEHRP Provisions (FEMA 302) where the alternates were not included. As a participant in the committee that developed these provisions, we know that the intent of the footnote is to apply to wall bracing that has no explicit overturning restraint. The alternate bracing panels do have explicit overturning restraint and should not be subject to the 2:1 h/w limit.

Question 2: Table 2308.12.4 requires a minimum length of wall bracing per each 25 linear feet of braced wall line, so how do the alternates per Section 2308.9.3.1 and 2308.9.3.2 contribute toward meeting the required amounts?

Answer 2: Each alternate braced wall panel per Section 2308.9.3.1 and 2308.9.3.2 is intended to replace 4-ft of bracing. In other words, they count as 4-ft of bracing even though they all actually measure less than 4-ft.