How to create nonlinear combinations for a nonlinear calculation?
A nonlinear calculation in SCIA Engineer can only be executed after nonlinear combinations have been created. This is possible via the Main menu > Load cases, combinations > Nonlinear combinations.
The available types for Nonlinear combinations are only ‘Ultimate’ and ‘Serviceability’.
This while for Linear combinations can be chosen from 3 types, each time for ULS and SLS: Linear (Simple) – Envelope – Code (e.g. EC-EN).
For a fact, all Nonlinear combinations have as type ‘Linear’ (Simple)!
This means a considerable effort is often required to create all Nonlinear combinations manually. The next steps show how to simplify this process:
1) Open the window Combinations. Suppose that 2 Code combinations have been created, EN ULS and EN SLS. Execute for both the action “Explode to linear”. By doing so the underlying Linear combinations are generated:
2) Open the window Nonlinear combinations. Choose here for the option “New from linear combinations”:
The window Combinations opens automatically. Now all (or part of) the linear combinations can be selected. Click [Close] afterwards.
The selected combinations are then automatically converted to nonlinear combinations; the content and coefficients of the linear combinations are maintained.
3) To ask now the envelope result of the nonlinear combinations, Result classes have to be defined. Go to the Main menu > Load cases, combinations > Result classes.
Create here e.g. the classes RC NL ULS and RC NL SLS, which contain respectively the nonlinear ULS and SLS combinations: