...
An
...
influence
...
surface
...
is
...
generated
...
for
...
a
...
specific
...
point
...
along
...
a
...
structure
...
subjected
...
to
...
moving
...
load,
...
where
...
the
...
variation
...
of
...
a
...
given
...
response
...
quantity
...
(axial,
...
shear,
...
or
...
flexural
...
force,
...
reaction,
...
etc.)
...
at
...
that
...
specific
...
point
...
is
...
plotted
...
as
...
the
...
moving
...
load
...
travels
...
across
...
the
...
structure.
...
The
...
influence
...
surface
...
provides
...
insight
...
into
...
the
...
structural
...
response
...
expected
...
at
...
a
...
point
...
within
...
a
...
structural
...
member
...
or
...
connection
...
relative
...
to
...
where
...
the
...
structure
...
is
...
subjected
...
to
...
loading.
...
Resolution
...
of
...
the
...
influence
...
surface
...
is
...
integral
...
to
...
...
...
analysis
...
.
...
For
...
example,
...
Figure
...
1
...
presents
...
an
...
influence
...
line
...
which
...
indicates
...
the
...
flexural
...
response
...
(Moment
...
3-3)
...
which
...
occurs
...
at
...
the
...
midspan
...
location
...
of
...
the
...
left
...
span
...
as
...
a
...
vehicle
...
load
...
moves
...
across
...
the
...
two-span
...
continuous
...
girder
...
system.
