You cannot have non-linear boundary conditions in a dynamic analysis (because the Eigen solution techinique is linear). Therefore, all non-linear restraints that were defined in the Piping Input must be linearized.
CAESAR II can perform this linearization process in-line with the Dynamic Analysis, based on a "Static Load Case" that you reference. This is the first data item on the "Control Parameters" dialog: "Static Case for Non-Linear Restraint Status".
CAESAR II takes the static load case that you specify and evaluates that status of each non-linear restraint based on the output from that specified load case. For a +Y, the output is evaluated to determine if the pipe lifted off or caused a downward load. If the pipe lifted off, then the +Y restraint is removed from the Dynamic Analysis. If the pipe was in contact with the restraint (caused a negative load), then the +Y is changed to a full Y.
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Regards,
Richard Ay - Consultant