achievable against high-severity threat levels (Figure 31). Relative to
other forms of construction, masonry walls provide penetration times only
slightly greater than stud/girt construction and for the same wall thickness,
masonry walls provide penetration times that are much less than reinforced
concrete. If additional penetration time is required, consider one or more
of the following options depending on the threat severity level.
c) Retrofit options for medium-severity threats. Several
techniques for hardening both hollow and mortar-filled 8-inch (200-mm) CMU
block are illustrated in Figures 50 and 51. Note that the retrofit hardening
layers are applied to the interior of the cross section. These options were
specifically designed and tested to provide enhanced attack resistance. The
CMU sections vary in the type of retrofit materials used. The data in
Figures 50 and 51 show the penetration times achievable by adding 3 to 4
inches (75 to 100 mm) of steel fiber-reinforced (i.e., ferro-cement)
concrete, expanded steel grating, and other options.
d) Retrofit options for high-severity threats. Consider
those retrofit options shown in Figures 50 and 51 for 8-inch (200-mm) CMU
block. The penetration times can be doubled from the values shown in Figure
33 by simply fixing a 10-gauge (3.4-mm) sheet steel (ASTM A589) to the
interior surface of the wall using lag screws or bolts. If this is still not
adequate, the steel-ply options summarized in Table 38 and Figures 46 through
48 or the riveted or welded grating shown in Figure 49 can be used. The
reader is referred to par. 184.108.40.206(1)(d) for further discussion.
Stud/Girt Wall Construction
a) Representative existing construction. Stud walls are
used in the construction of wood or light metal frame buildings. The basic
frame consists of wood or metal vertical supports, usually 2 by 4 inches (50
by 100 mm) or 2 by 6 inches (50 by 150 mm), placed 12, 16, or 24 inches (300,
400, or 600 mm) on-center. Metal girts are horizontal framing members used
in rigid frame systems. They range in depth from 6-1/2 to 9-1/2 inches ( 165
to 240 mm) and are spaced 2 to 7-1/2 feet (600 to 2,250 mm) on-center. An
architectural finish is attached to the exterior side of the stud or girt,
and an interior wall finish may be attached to the interior side. The seven
basic types of stud/girt wall construction include: stud and stucco, stud and
wood siding stud and plywood siding, stud and shingle siding, stud and
composition siding, stud/girt industrial siding, and conventional masonry
veneer construction. It should be noted that wood wall construction for
permanent buildings is confined primarily to housing and minor structures.
Wood construction must be in accordance with the fire protection requirements
set forth in MIL-HDBK-1008, Fire Protection for Facilities Engineering,
Design and Construction.