May 11, 2023
|
RISA-3D,
Wood
Do
you
need
to
include
effective
length,
le,
per
NDS
Table
3.3.3
for
your
wood
design?
Yes?
While
RISA-3D
does
not
automatically
follow
this
le
procedure
per
NDS
Table
3.3.3,
you
as
the
engineer
can
input
these
values
once
you
have
them
calculated.
Inputting
the
effective
length
value
in
RISA-3D
allows
the
program
to
use
the
correct
value
for
the
Rb
calculations.
NDS
provisions
use
an
effective
length
approach
to
account
for
different
load
and
support
conditions.
How
does
NDS
do
this?
By
calculating
the
slenderness
ratio,
Rb
using
the
effective
length,
le,
instead
of
the
unbraced
length,
lu.
Follow
the
steps
below
to
calculate
and
input
the
effective
length
into
RISA-3D.
STEP
1:
Determine
your
span
type
and
loading
condition.
STEP
2:
Calculate
and
determine
the
effective
length
values
from
Table
3.3.3
based
on
the
unbraced
length
and
loading.
lu
=
10ft
d
=
9.25in
=
0.77ft
lu/d
=
12.97
>
7,
therefore
le
=
1.63lu
+
3d
=
18.61ft
STEP
3:
Enter
the
effective
length
value
calculated
into
your
unbraced
length
properties
section
in
RISA-3D.
Additional
information
regarding
this
topic
can
be
found
in
our
Help
file
in
the
Unbraced
Lengths
section…
