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Section 5
5-289
DISPLACEMENT MODE
With this mode, the support joint displacement is modeled as an
imposed joint displacement. The joint directions where
displacement may be specified must be defined (same for all cases)
in the SUPPORT command, see section 5.27.1. Any beam
members, springs or finite elements will be considered in the
analysis. Other loading, inclined supports, and master/slave are all
considered. Any number of cases may have displacements entered.
However, all cases will have zero displacements at the enforced
directions if no displacement values are entered for that case. At
inclined supports the displacement specification is assumed to be
in the inclined direction. Displacements may not be specified at
slave directions.
If some cases are to have spring supports and others enforced
displacements at the same joint directions, then two PERFORM
ANALYSES must be used with the CHANGE command in
between. The first perform analysis could have the SUPPORTS
with springs, no enforced directions, and with the load cases
without displacements. The second perform analysis would then
have SUPPORTS without springs but with enforced directions and
the cases with displacements.
Displacement Mode Restrictions
The Support Displacement command may be entered only once per
case. Spring directions and Enforced directions may not both be
specified at the same joint direction in the same Perform Analysis
step.
LOAD MODE
With this mode, the support joint displacement is modeled as a
load. Only beam members (not springs or finite elements) are
considered in computing the joint load distribution necessary to
cause the displacement. Other loading, inclined supports, and
master/slave are also not considered. These unconsidered factors,
if entered, will result in displacements other than those entered