Action > Buckle

Calculation of the linear buckling failure load of a structure. The calculation is based on solving the respective eigenvalue problem [K_T] - l*[K_sig] = 0. [K_T] stands for the tangential stiffness matrix, [K_sig] is the so-called initial stress matrix or geometric matrix. In beam structures it is only dependent on normal forces in the beams and describes the so-called p-delta effect. l is the calculated load factor for reaching the theoretical bifurcation load.

Setting	Description
Action	Code of the selected Action. It is possible to switch to another action without leaving and re-entering the input function.
Action will be skipped (Option)	The action will be skipped in the calculation process if the option is selected.
Input-1 > Number of natural modes	The function buckle allows for calculating not only the lowest bifurcation mode but also higher order modes. Each mode will be calculated and stored as a fictitious load case.
Input-2 > Reference load case name	Name of the basic load case defining the normal forces in the structure for calculating the initial stress matrix [K_sig].
Input-3 > (Variable)	This option allows for separating the reference load case into a fixed part and a variable part. It works in combination with the load set option "Load set can be increased". If the option Var is set, the calculated factor only refers to the part of the load case which has the flag "Load set can be increased". Note: The initial stress matrix [K_sig] is in this case split into a constant part [K_sig1] and a factored part [K_sig2] and the modified Eigenvalue problem [K_T] - [K_sig1] - l*[K_sig2] is solved.
Output-1 > Start output loadcase	Prefix of the names of the generated fictitious load cases presenting the normalized bifurcation modes. The actual load case name is generated by adding to this prefix the character # and the mode number (e.g. Bifurc#1 for the first mode if the prefix is Bifurc).
Output-2 > List file	Name of the list file. Default (*): buckxxx.lst with xxx being the load case name prefix as specified in Output-1. No list file will be created if the input field is empty.
Delta-T	Duration of the Action (not applicable for this action)
Description	Descriptive text for the selected Action (max. 80 characters)