A Method for System Buckling Analysis of Plane Sway Frame

Presented in this paper is a simple and practical method for buckling analysis of the overall structural system. The method is developed from the idea that the stiffness (for a SDOF system) or determinant of stiffness matrix (for a MDOF system) is getting to zero as the system is loaded to bucking mode, or the loads reaches the buckling load of the system. A negative stiffness (matrix) is introduced to take the effect of axial loads on the stiffness (matrix) of the system into account and the stiffness (matrix) is modified by this negative stiffness (matrix). To get the buckling load of the overall system, first order analysis (P-Δeffect) is performed with a simple method suggested. The second order analysis (P-δ) is performed by the introducing of a force modification factor to modify the buckling load from first order analysis. Application examples are presented and the results are compared with result obtained from system buckling analysis with FEA. The simplicity, effectiveness and the accuracy of the suggested method is demonstrated.