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THE
FOLLOWING IS A
DESCRIPTION OF BUILDING
DESIGN
IRREGULARITIES
THAT CAN LEAD TO
INCREASED DAMAGE
IN EARTHQUAKES
2.4.1.1.1
In-Plane
Discontinuity
Irregularity:
An in-plane
discontinuity
irregularity
shall be
considered to
exist in any
primary element
of the
lateral-force-resisting
system whenever
a
lateral-force-resisting
element is
present in one
story, but does
not continue, or
is offset within
the plane of the
element, in the
story
immediately
below. Figure
2-1 depicts such
a condition.
2.4.1.1.2
Out-of-Plane
Discontinuity
Irregularity:
An out-of-plane
discontinuity
irregularity
shall be
considered to
exist in any
primary element
of the
lateral-force-resisting
system when an
element in one
story is offset
out-of-plane
relative to that
element in an
adjacent story,
as depicted in
Figure 2-2.
2.4.1.1.3
Severe Weak
Story
Irregularity:
A severe weak
story
irregularity
shall be
considered to
exist in any
direction of the
building if the
ratio of the
average shear
DCR of any story
to that of an
adjacent story
in the same
direction
exceeds 125%.
For buildings
with flexible
diaphragms, each
line of framing
shall be
independently
evaluated.
2.4.1.1.4
Severe Torsional
Strength
Irregularity: A
severe torsional
strength
irregularity
shall be
considered to
exist in any
story if the
diaphragm above
the story under
consideration is
not flexible
and, for a given
direction, the
ratio of the
critical element
DCRs for primary
elements on one
side of the
center of
resistance of a
story, to those
on the other
side of the
center of
resistance of
the story,
exceeds 1.5.
Proceed
to RISK
ASSESSMENT
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