DS 2-8 Earthquake Protection for Water-Based Fire ... - FM Global

2-8 Earthquake Protection
Page 26 FM Global Property Loss Prevention Data Sheets
Fig. 14. Detail of connection of sway brace to side of wood beam with through bolt.
5. Adhere to the following guidelines for attachments to wood members:
a) Connect sway braces to wood components with through bolts whenever practicable (see Fig.
14). When roof configuration or other factors make the use of through-bolts impractical, lag screws
may be used.
b) Use neither through-bolts nor lag screws in wood members less than 3- 1 ⁄ 2 in. (90 mm) in least
dimension.
c) Dimensionally locate through-bolts and lag screws with respect to structural members per Fig.
15.
d) Pre-drill holes for through-bolts 1/32 or 1/16 in. (0.8 or 1.6 mm) larger in diameter than the bolt
diameter.
e) Pre-drill lead (pilot) holes for lag screws in accordance with Table 8 and Figure 16.
f) Install lag screws properly, by turning them with a wrench, not driving them with a hammer.
g) Select the appropriate fastener size from Tables 9 and 11 (Tables 10 and 12 for metric) for
through-bolts and lag screws in wood, based on the configuration of the fastener with respect to
the structural member, and the angle of the brace from the vertical. The load values given correspond
to the applied horizontal seismic load (either H or a fraction of H not less than H/2, depending on
sway bracing configuration) for the worst-case angle from the vertical for the range of angles given.
In other words, the seismic design load on the fastener must be less than the table values for the
fastener size and configuration selected.
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