...
Should
...
I
...
apply
...
rigid
...
zones
...
when
...
checking
...
punching
...
shear?
...
Extended
...
Question:
...
I
...
am
...
finding
...
large
...
differences
...
in
...
the
...
moment
...
demands
...
for
...
punching
...
shear
...
when
...
rigid
...
zones
...
are
...
applied
...
over
...
columns.
...
Is
...
there
...
an
...
explanation
...
for
...
this
...
behavior,
...
and
...
is
...
there
...
a
...
recommendation
...
for
...
whether
...
or
...
not
...
to
...
include
...
this
...
option?
...
Answer:
...
When
...
the
...
option
...
to
...
Include
...
Automatic
...
Rigid
...
Zone
...
Area
...
Over
...
Column
...
is
...
specified,
...
the
...
rigidity
...
of
...
the
...
connection
...
increases,
...
causing
...
deflection
...
and
...
slab
...
reinforcement
...
to
...
decrease.
...
Further,
...
unbalanced
...
moments
...
generally
...
increase,
...
leading
...
to
...
higher
...
...
...
ratios.
...
While
...
this
...
modeling
...
decision
...
is
...
at
...
the
...
discretion
...
of
...
the
...
engineer,
...
we
...
generally
...
recommend
...
including
...
the
...
rigid
...
zones
...
over
...
column
...
objects.
How do I eliminate the negative moment at the face of columns and walls?
Answer: To decrease or eliminate negative moments, remove the rigid areas located over columns and walls, and uncheck the Wall Takes Out-of-plane
...
Moments
...
option.
...
When
...
walls
...
are
...
not
...
unidirectional,
...
or
...
when
...
they
...
do
...
not
...
follow
...
the
...
direction
...
of
...
design
...
strips,
...
slab
...
continuity
...
will
...
cause
...
some
...
negative
...
moment
...
which
...
is
...
usually
...
small
...
or
...
negligible.
...
Results
...
may
...
be
...
further
...
improved
...
by
...
decreasing
...
the
...
maximum
...
...
size.
...