dear sir
can you explain me what is the difference between linear and non linear Restraint . because we are generally use non-linear Restraint during static stress analysis where as linear restraint use for Dynamic stress analysis.

i had confusion that how the Same support like +y will work as a non-linear and linear support for static and dynamic analysis.
can some body expalain me with example.

prakash kumar

dear prakash,

linear restraint:
full Y support
no gaps allowed
no friction

non-linear restraint:
+y support
gaps allowed
friction allowed

yes dynamic stress analysis should be linearised and you have to use full y support,that supports are called Hold down supports. hold down supports are important in dynamic analysis. regarding the topics you can refer from caesar ii manual or documents.

thank you very much

but still i have some confusion regarding this topic.

when we are performing the static stress analysis and providing +y support. definetly it will be act non- restraint support. but when we are using the same system for dyanamic analysis whether same support(+y) will act like Y (rest+ hold down) . if it is like that then how it is possible the same system will work rest as well as rest with hold hown, but physical support is rest.

i appreciate your fast clarification.

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.

thank you for your prompt reply.

thanks

prakash