August 17, 2016
|
RISA-3D,
New,
Warping,
Torsion
Twisting
of
a
member
or
frame
induces
torsional
forces
and
stresses.
This
is
included
in
the
RISA-3D
analysis
as
long
as
you
have
the
Torsional
Warping
checkbox
selected
on
the
Solution
tab
of
(Global)
Model
Settings.
The
primary
reference
used
in
the
development
of
RISA-3D’s
torsional
calculations
was
the
AISC
Design
Guide
#9,
Torsional
Analysis
of
Structural
Steel
Members.
It
is
important
to
remember
that
RISA-3D
models
warping
members
using
CASE
2
only.
As
shown
in
the
Torsion
reference,
CASE
2
represents
the
torsionally
fixed
and
warping
fixed
end
conditions
for
the
member.
Thus,
a
member
would
be
then
subjected
to
an
equal
and
opposite
point
torque
at
the
end
of
the
member.
Note:
RISA’s
calculation
of
torsion
stresses
is
good
for
capturing
the
torsion
due
to
racking
of
the
structure,
not
point
or
line
torques
on
an
individual
member.
That
type
of
check
is
not
supported.
Stress
Results
RISA-3D
calculates
and
lists
the
torsional
stresses
for
the
members
of
the
structure,
including
the
warping
stresses.
These
are
reported
in
the
Member
Torsion
spreadsheet.
For
warping
shapes
(I’s
and
C’s),
three
separate
stresses
are
calculated:
pure
torsion
shear,
warping
shear
and
warping
normal
(bending)
stresses.
Code
Check
Results
These
torsional…
