Elastic Critical Loads for Plane Frames by Transfer Matrix Method

The transfer matrix methodology is adapted to the stability analysis of unbraced frames. A nonbranching chain of members is generated by partitioning the structure at floor levels. Geometric nonlinearity is accounted for by introducing the stability functions into the member stiffness and the flexural effect of axial forces into the equations of equilibrium. Field and station transfer matrices are derived on the basis of a minimum number of only the essential degrees of freedom per floor level. Displacements and internal forces are determined by a direct procedure that combines a gradual increase of the applied load with iteration at each load level. The critical load is located to a specified degree of accuracy on the first singularity of the appropriate solution matrix. The developed formulation accounts for joint and base flexibility as well as lateral load and fixed‐end moments effects. The accuracy and efficiency of its computer implementation are tested through comparison of its predictions with res...