Buckling Factor for Variable Load

I know I can use ASE → EIGE to get buckling factor for PLC.

Now I have 2 load cases, G for permenet load, and Q for variable load.
Both load cases act on the structure at the same time.

If I use PLC G, then I get buckling factor for G;
and if I PLC Q, then I get buckling factor for Q;

I want to get buckling load: 1.0 x G + buckling factor x Q, which cause the structure to buckle.

In Midas etc, user can specify which load is a “constant load”, and which load is “variable load” in buckling analysis setting,


so the buckling load = constant load + buckling factor x variable load

How to do it in Sofistik?

do you know how it works in details? program has solve multiple load vectors and resultant load vectors are ,superposition’’ of many results?

What do you mean by “detail”?

In Midas, if the constant load G=2kN, variable load Q=1kN, and if the buckling load is 5kN,
then buckling factor = (5-2)/1=3
or buckling load = 2kN + 3*1kN = 5kN

Linear Buckling Analysis – Constant + Buckling Factor * Variable Case
These are descriptions of the feature in Strand 7 R3 and Midas Gen / Civil

Strand 7 R3
The linear buckling solver calculates factors applied to a load case to cause the structure to buckle. The load case is referred as the Variable Case in R3 and the buckling factors scale the loads in that load case.
R3 also offers the option to select a Constant Case together with the variable case. If a constant case is selected, that result case is assumed to be applied to the structure with a constant load factor of 1.0. The linear buckling solver then calculates the load factor that scales only the variable case to cause the structure to buckle while the load factor on the constant case remains as 1.0.

Midas Gen / Civil
Buckling Combination
Enter the load cases for the buckling analysis. Different Load Cases with the corresponding Scale Factors may be entered.
Load Type
Variable: Consider increase or decrease in loads (live loads, etc.)
Constant: Do not consider increase or decrease in loads (self-weight, dead loads)