STABILITY OF THE COLUMN WITH CHANGED LINEAR CROSS SECTIONS BY MATRIX STIFFNESS METHOD
In the paper, the author constructed the stiffness matrix of bending compressive elements whose cross-section changes according to the first-order rule, the displacement function selected as the third polynomial satisfying the boundary conditions of the problem. The stiffness matrix of simultaneously compressible bending elements includes: The hardness matrix of a common linear elastic bar element has a linear change cross-section and a stiffness matrix of the inner rod element. it takes into account the effect of longitudinal force P on the element flexural stiffness. Payload P acts at both ends of the element. The overall hardness matrix is determined by the index method, the critical load is determined by the specific value problem of the overall hardness matrix.