During load combination,we have two option
1.Add from analysis
2.From regular or irregular structure.
I would like to know which criteria do we use to select type of load combination between regular and irregular?how does the two option between regular and irregular affect my design
Option 1 = Add load combinations from analysis - gives you facility to perform design of elements by select the load combinations that you have defined in your analysis file.
Option 2 = Add load combination from standard template available in RCDC based upon the load cases selected in RCDC for design.
RCDC has a standard load combination set which is Design code specific and are as per clauses mentioned in each design code.
The load combination will get populated on the load combinations window in RCDC as per the load cases that you have selected.
You can add load combination for a Regular or an Irregular where --
Regular Building = Non-orthogonal structure.
Ir-regular Building = Orthogonal structure and Loading on the structure.
So depending upon the type of your structure, you can add load combinations.
You can also view the entire standard set of load combinations in RCDC - refer below image
Ok may you help me with more elaboration, what is the difference between Orthogonal and Non orthogonal structure?
When the lateral load resisting elements are not oriented along the orthogonal horizontal directions, the structure shall be designed for the effects due to full design earthquake load in one horizontal direction plus some percent of the design earthquake load in the other direction. The percent varies from design code to design code.