511C.3 Crosswalls. Crosswalls when used shall meet the requirements of this section.

511C.3 Crosswalls. Crosswalls when used shall meet the requirements of this section.

511C.3.1 Crosswall definition. A “crosswall” is a wood-framed wall sheathed with any of the materials described in Table 5C-D or 5C-E or other system as defined in Section 511C.3.5. Spacing of crosswalls shall not exceed 40 feet (12.19 m) on center measured perpendicular to the direction of consideration and shall be placed in each story of the building. Crosswalls shall extend the full story height between diaphragms.

EXCEPTIONS:

1. Crosswalls need not be provided at all levels in accordance with Section 511C.4.2(4).

2. Existing crosswalls need not be continuous below a wood diaphragm at or within 4 feet (1.219 m) of grade, provided:

(1) Shear connections and anchorage requirements, Section 511C.5 are satisfied at all edges of the diaphragm.

(2) Crosswalls with total shear capacity of 0.08åWd interconnect the diaphragm to the foundation.

(3) The demand-capacity ratio of the diaphragm between the crosswalls that are continuous to their foundations shall be calculated as:

DCR = (0.332Wd+Vca)/2vuD (5C-4)

and DCR shall not exceed 2.5.

511C.3.2 Crosswall shear capacity. Within any 40 feet (12.19 m) measured along the span of the diaphragm, the sum of the crosswall shear capacities shall be at least 30 percent of the diaphragm shear capacity of the strongest diaphragm at or above the level under consideration.

511C.3.3 Existing crosswalls. Existing crosswalls shall have a maximum height-to-length ratio between openings of 1.5 to 1. Existing crosswall connections to diaphragms need not be investigated as long as the crosswall extends to the framing of the diaphragm above and below.

511C.3.4 New crosswalls. New crosswall connections to the diaphragm shall develop the crosswall shear capacity. New crosswalls shall have the capacity to resist an overturning moment equal to the crosswall shear capacity times the story height. Crosswall overturning moments need not be cumulative over more than two stories.

511C.3.5 Other crosswall systems. Other systems, such as moment resisting frames, may be used as crosswalls, provided that the yield story drift does not exceed 1 inch (25.4 mm) in any story.