Bifurcation Analysis of Multistory Building Frames by Marching Technique

A computer program is presented to show the algorithm that is used to give the buckling load factor and the effective lengths of all columns in a multistory building frame when these columns are subjected to a set of primary axial forces. Since the buckling load factor is the lowest multiplier of the primary axial forces that makes the determinant of the global stiffness matrix equal to zero, it has to be found by trial and error. It is found that the determinant of the global stiffness matrix is the product of the pivots used in the piecewise small inversions within the earlier one on bifurcation analysis lies in the way by which the determinant is computed. Significant amount of computer time is saved because of the need of repetitive computations of the determinant at many trial values of the buckling load factor.