Evaluation of effective length factors in braced frames

Abstract

A designer-oriented iterative method for the evaluation of effective length factors in braced frames is described. The formulae used in the method have been expressed in terms of effective length factors because designers use this parameter, rather than the values of critical buckling loads, in the analysis and design of columns. The method takes into account the reduced stiffness of restraining members due to the presence of significant axial forces and also allows for the stabilizing effect of tension members. Application of the method is demonstrated by numerical examples. Keywords: braced structures, buckling of continuous columns, frame buckling, truss buckling, effective length factors, accurate stability functions, linear approximations of stability functions, structural stability.