(3) Conventional light frame construction, as
defined in Section 12.5 of FEMA 302, may be used
(b) Modification factors, m, for enhanced
only
for
buildings
required
to
comply
with
performance objectives and linear elastic procedures,
Performance Objective 1A.
are provided in Table 7-7 for deformation-controlled
reinforced masonry in-plane walls and piers.
(4) Deflections. Procedures for calculating
the deflection of wood frame shear walls are not yet
(c)
Modeling parameters and numerical
available.
The maximum height-width limitations
acceptance criteria for nonlinear procedures applied
given herein are presumed to satisfactorily control
to deformation-controlled reinforced masonry walls
deflections.
Relative stiffness of wood stud shear
and piers are provided in Table 7-8.
walls will be measured by the effective lineal width
of walls or piers between openings.
(d) Expected strength. The expected lateral
strength of reinforced masonry, QCE, in either flexure
(5)
Wall tie-down.
The end studs of any
or shear shall be determined using 1.25 fy for the
plywood sheathed shear wall and/or shear wall pier
contribution attributed to the reinforcement.
will be tied down in such a manner as to resist the
overturning forces produced by seismic forces
(e)
Lower-bound strength.
The lower-
parallel to the shear wall. This overturning force is
bound strength for all other actions in URM or
sometimes of sufficient magnitude to require special
reinforced masonry shear walls shall be taken as the
steel attachment details. A commonly used detail is
design strength defined by Section 11.5.3 of FEMA
shown on Figure 7-18.
302.
(6) Acceptance criteria.
i.
Wood Stud Shear Walls.
(a)
Compliance with the provisions of
(1) General design criteria. The criteria used
FEMA 302 constitutes the acceptance criteria for
to design wood stud shear walls are presented in
Performance
Objective
1A
for
light
frame
Chapter 12 of FEMA 302. Additional criteria and
construction.
details are included in the following paragraphs.
(b) Response modification factors, R, for
(2) Allowable shears for plywood. Details of
Performance 1A are provided in Table 7-1 for light
plywood sheathed walls are shown in Figure 7-17,
frame walls in bearing-wall systems and building
and the allowable shears are shown in Table 7-9.
frame systems.
When a combination of plywood and other materials
is used, the shear strength of the walls will be
determined by the values permitted for plywood
alone.
7-43
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