Filter
Top Products
Section 5
5-341
g) If a RESPONSE SPECTRUM or TIME LOAD is specified
within a load case or the MODAL CALCULATION command
is used, a dynamic analysis is performed.
h) In each of the "n" iterations of the PDELTA analysis, the load
vector will be modified to include the secondary effect
generated by the displacements caused by the previous
analysis.
There are two options to carry out P-Delta analysis.
1) When the CONVERGE command is not specified: The member
end forces are evaluated by iterating “n” times. The default
value of “n” is 1 (one).
2) When the CONVERGE command is included: The member
end forces are evaluated by performing a convergence check
on the joint displacements. In each step, the displacements are
compared with those of the previous iteration in order to check
whether convergence is attained. In case “m” is specified, the
analysis will stop after that iteration even if convergence has
not been achieved. If convergence is achieved in less than “m”
iterations, the analysis is terminated. (DO NOT ENTER “n”
when CONVERGE is provided)
3) To set convergence displacement tolerance, enter SET
DISPLACEMENT f command. Default is maximum span of the
structure divided by 120.
Example
Followings are some example on use of the command for P-Delta
analysis.
PDELTA ANALYSIS
PDELTA 5 ANALYSIS
PDELTA ANALYSIS CONVERGE
PDELTA ANALYSIS CONVERGE 5