steel tube concrete;  bending members;  ultimate bearing capacity;  elastoplastic analysis;  Finite elements

The elastic-plastic stiffness matrix of steel tube concrete bending members is derived by using the finite element method of segmented and block rod structure based on fiber model, and a calculation model for calculating the elastic-plastic stable bearing capacity of steel tube concrete bending members is proposed, and the corresponding calculation program is compiled. The proposed method and procedure were used to calculate the elastoplastic ultimate bearing capacity of the axial compression and eccentric compression long column of steel tube concrete with round pipe cross-section, and the theoretical analysis results were in good agreement with the experimental and theoretical results reported in the literature.