This function, determines elastic buckling load of prestressed stayed steel columns. the inputs are geometrical dimensions of core/main column, cross-arm and stayed system. This functions plots elastic buckling curves for symmetric and antisymmetric buckling modes. For more information about analytical methods for determining critical buckling load and ultimate capacity of stayed column please read below paper:
Miguel Serra, Ashkan Shahbazian, Luís Simões da Silva, Liliana Marques, Carlos Rebelo, Pedro Colmar Gonçalves da Silva Vellasco (2015) A full scale experimental study of prestressed stayed columns, Engineering Structures, Volume 100, Pages 490-510.
Link: http://www.sciencedirect.com/science/article/pii/S0141029615004095