...
When
...
static
...
loading
...
is
...
applied
...
in
...
the
...
X
...
direction,
...
net
...
reaction
...
in
...
the
...
Y
...
direction
...
will
...
be
...
zero,
...
though
...
individual
...
reactions
...
may
...
be
...
nonzero,
...
depending
...
on
...
the
...
type
...
of
...
structure.
...
For
...
example,
...
when
...
a
...
single-story
...
frame
...
system
...
with
...
four
...
columns,
...
arranged
...
in
...
a
...
square
...
plan
...
with
...
interconnecting
...
beams
...
at
...
the
...
roof
...
level,
...
is
...
subjected
...
to
...
a
...
horizontal
...
point
...
load
...
in
...
the
...
major
...
direction
...
at
...
the
...
top
...
of
...
one
...
column,
...
torsion
...
will
...
cause
...
horizontal
...
support
...
reactions
...
in
...
the
...
direction
...
orthogonal
...
to
...
loading.
...
Given
...
a
...
dynamic
...
loading
...
condition,
...
net
...
reactions
...
are
...
in
...
equilibrium
...
for
...
both
...
applied
...
loading
...
and
...
...
...
.
...
When
...
the
...
structural
...
center
...
of
...
stiffness
...
differs
...
from
...
the
...
center
...
of
...
...
,
...
loading
...
in
...
the
...
X
...
direction
...
may
...
generate
...
motion
...
in
...
the
...
Y
...
direction.
...
This
...
motion
...
will
...
correlate
...
with
...
a
...
set
...
of
...
inertial
...
forces
...
and
...
support
...
reactions
...
orthogonal
...
to
...
the
...
direction
...
of
...
loading.
...
Most
...
non-symmetric
...
structures
...
exhibit
...
orthogonal
...
reactions
...
and
...
response
...
quantities
...
when
...
subjected
...
to
...
either
...
static
...
or
...
dynamic
...
loading.
...
This
...
behavior
...
naturally
...
occurs
...
as
...
a
...
structure
...
establishes
...
equilibrium.
...
Design
...
must
...
account
...
for
...
these
...
orthogonal
...
forces,
...
along
...
with
...
all
...
others
...
which
...
result
...
from
...
load
...
application.