Improved G‐Factor Method For Evaluating Effective Lengths of Columns

Design specifications for columns include nomographs for calculating effective length factors. The method, which is simple to use, requires the designer to evaluate G at each end of the column, but only positive G‐factors result, and in the case of sway‐prevented structures, effective length factors are always less than one. In practice, some columns may have values of K greater than one, corresponding to negative values of G. This paper expands the present graphical method so that the correct set of K‐values can be determined. An iterative procedure is presented, based on linearized stability functions that effectively account for the presence of axial forces in the restraining members. The improved G‐factor method is illustrated by numerical examples that are not, in general, covered by the nomographs where the beams are assumed to offer significant restraint.