Southwell plot is a useful method of determining critical buckling load from test data within the elastic region without loading in the vicinity of critical load. This paper discusses a modified computational Southwell plot which is employed for analyzing the global buckling modes of a system with the structural members subjected to monotonically increasing axial loading. The novel formulation uses dynamic stiffness as a function of the axial load to compute the dynamic response of the structure from which the fundamental natural frequencies are obtained. This forms a classical problem in buckling analysis and this gives it a new outlook. Gradually decreasing frequencies are plotted with reference to the axial loads on the structural members and are extrapolated to obtain the global buckling loads. The methodology delivers a practically useful method of analyzing buckling modes of complex frames and other structures. The paper verifies some benchmark problems of buckling using this formulation and extends the procedure to typical industrial framed structures.

Keywords: Southwell plot, Global buckling modes, Dynamic stiffness.