3. Reinforced concrete shear walls.
concrete shear walls described in Paragraph iii
above.
i.
Controlled by flexure.
For shear
walls in which the vertical reinforcement is expected
(c)
Force-controlled actions. Structural
components shall have lower-bound strengths, QCL,
to yield in flexure prior to the wall exceeding its
not less than the required strength, QUF, from the
shear capacity, the acceptance criteria in Table 7-4
are provided in terms of the plastic rotation, 2 , as
appropriate combinations of seismic and gravity load
effects. Lower-bound strengths, QCL, are defined in
indicated in Figure 6-4 and are similar to that for
concrete moment-resisting frames in Paragraph 2
Paragraph 6-3a(3)b and in Chapters 7 through 10.
above with the depth, d, in Equation 6-11 to be
replaced by the length of the wall.
(d). Reanalysis. The results of the analysis
must be carefully monitored to determine whether
ii.
Controlled by shear.
For shear
any of the structural components have exceeded the
walls when the shear capacity is attained prior to
deformation limits indicated in Chapters 7 through
flexural yielding of the reinforcement, the tabulated
10 for the desired performance objectives. Minor
acceptance criteria values in Table 7-5 represent
exceedance (i.e., 10 to 15 percent) of the deformation
allowable values of the interstory drift ratio, ) /h,
limits in a limited number of components may be
with reference to Figure 6-2b, and it is not necessary
acceptable if it can be demonstrated that the
to determine ) y.
additional deformation does not have an adverse
effect on the performance of the structure. All other
iii. Coupling beams. The acceptance
components with excessive deformations should be
criteria in Table 7-4, for coupling beams controlled
strengthened to meet the acceptance criteria. If the
by flexure, are evaluated as shown in Figure 6-5 for
revised member sizes for the components are
beams in moment frames.
Coupling beams
significant, a reanalysis may be required to confirm
controlled by shear are evaluated as indicated above
an acceptable response. Similarly, if the results of
for walls controlled by shear, and the acceptance
the analysis indicate that a number of the
criteria are tabulated in Table 7-5.
components or elements are overdesigned by a factor
of 10 to 15 percent, the overdesigned components or
4. Reinforced masonry shear walls. The
elements shall be redesigned, and the analysis
acceptance criteria for these shear walls, tabulated in
reported, unless it can be demonstrated that the
Table 7-9, are provided in terms of drift ratios, ) /h,
overdesign is cost-effective, or otherwise beneficial.
as indicated in Figure 6-2b. Acceptance criteria for
If the structural members are required to be
coupling beams for reinforced masonry walls are
substantially stronger or stiffer, as compared to the
similar to criteria for coupling beams in reinforced
design for gravity loads, the designer should
consider the use of a supplementary structural
6 - 15
Previous Page
