...
The
...
pattern
...
live-load
...
factor
...
(Pllf)
...
is
...
intended
...
to
...
account
...
for
...
variability
...
in
...
the
...
live-load
...
arrangement
...
on
...
a
...
structure.
...
Since
...
live-load
...
pattern
...
is
...
not
...
automated,
...
Pllf
...
approximates
...
its
...
design
...
effect.
...
When
...
nonzero
...
Pllf
...
is
...
assigned
...
to
...
a
...
...
object,
...
positive
...
design
...
moments
...
are
...
calculated
...
assuming
...
a
...
simply
...
supported
...
condition
...
under
...
live-load
...
application.
...
While
...
this
...
does
...
affect
...
design
...
moments,
...
analysis
...
moments
...
are
...
not
...
affected.
...
Pllf
...
enables
...
users
...
to
...
specify
...
the
...
live-load
...
percentage
...
applied
...
to
...
a
...
frame
...
object
...
for
...
which
...
no
...
continuity
...
is
...
assumed.
...
Negative
...
moments
...
are
...
then
...
redistributed
...
in
...
a
...
manner
...
similar
...
to
...
that
...
of
...
moment
...
redistribution
...
from
...
yielding.
...
As
...
a
...
result,
...
positive
...
midspan-moment
...
values
...
increase.
...
Zero
...
Pllf
...
may
...
be
...
specified
...
to
...
avoid
...
moment
...
redistribution.
...
Pattern
...
live-load
...
factors
...
may
...
be
...
assigned
...
to
...
individual
...
elements
...
using
...
the
...
Design
...
>
...
Steel
...
Frame
...
Design
...
or
...
Concrete
...
Frame
...
Design
...
>
...
View/Revise
...
Preferences
...
command,
...
as
...
shown
...
in
...
Figure
...
1:
Example
The maximum positive midspan design moment induced by uniform dead- and live-load application would be calculated as follows:
where:
- f1 = code-based dead-load factor (1.2)
- f2 = code-based live-load factor (1.6)
- l = element length
- LL = distributed live load (force/length)
- MDL = positive dead-load moment with actual boundary conditions due to dead load only
- Mpos MAX - maximum positive midspan design moment assuming a simply-supported condition with no continuity for live load
Given point loading, Mpos MAX would be calculated similarly as for uniform loading, in which a simply supported condition is assumed and the live-load factors specified are applied.