The effective length factor of columns in steel framed buildings with end restraint effects

The present article presents a practical method to determine the effective length factor of multi-storey frames based on a rigorous analytical approach applied to a basic model judiciously parameterized in terms of geometry and load arrangement. The adopted novel model considers the different interactions and effects of varying the boundary conditions at the ends of the columns and beams that are connected to the column under consideration. Subsequently, parametric studies are presented to evaluate the influence of the boundary conditions at the ends of the columns located above and below the column under consideration on the effective length factor value K. It is worth specifying that these variations are considered for the braced and unbraced frame cases. A comparative study revealed substantial differences between the values of the effective length factors thus obtained and those calculated using the method recommended by Eurocode 3 and CCM97. The proposed charts and relating to the effective length factor value K associated with the double cross model adopted by Eurocode 3 and CCM97, are of practical significance as they are very useful in the conception and design of such frames.