Choice of methods of second order analysis
Eurocode 2 part 1-1: Design of concrete structures 5.8.5 Methods of analysis
There are two simplified methods of second order analysis:
(a) Method based on nominal stiffness
(b) Method based on nominal curvature
Method (a) may be used for both isolated members and whole structures, if nominal stiffness values are estimated appropriately. Method (b) is mainly suitable for isolated members. However, with realistic assumptions concerning the distribution of curvature, the method (b) can also be used for structures.
The selection of simplified method of second order analysis (a) and (b) to be used in a Country may be found in its National Annex.