Analysis options sets the
parameters for the eigenvalue calculation.
After the first
Max. Cycle ] number of iterations, the current calculated eigenvalue
is multiplied by [ Factor ], and used as an estimated eigenvalue
for the next [ Max. Cycle ] number of iterations. This continues
until either the convergence criteria is satisfied or when [ Max. Shift
] * [ Max. Cycle ] iterations are completed. There is
no general rule for an optimum [ Max. Shift ], [ Max. Cycle ],
and [ Factor ] combination, but experience has shown that [ Max.
Shift ] = 3, [ Max. Cycle ] = 10, [ FAC ] = 0.8
is a fairly good set of values to use.
[ Torsional Geometric Stiffness
] - if you are not interested in considering elastic local flange buckling,
then leave the option blank.
[ Approximate Shear Distortion
] - the option basically considers vertical stresses in the web.
This option is needed if you want to consider such effects as local web
crippling at concentrated loads and sideway web buckling
Also see Analysis
Checking [ UnSym. ] optionsets
the initial buckled shape to be unit out-of-plane displacement for the
left one third of the nodes, and one half out-of-displacement in opposite
direction for the remaining two thirds of the nodes.
Checking [ Sym. ] option
sets the initial buckled shape to be unit out-of-plane displacement for