There is a large diversity in the requirements for designing built-up compression members between international design codes. Most codes, including the North American standards and specifications specify the use of an equivalent or modified slenderness ratio. In general, all North American standards and specifications agree on the need of using a modified slenderness ratio, but differ in the factor used to multiply the local slenderness ratio. Theoretically it is difficult to estimate the exact value of this factor, and using experimental methods does not capture the exact value of this factor either. Hence, a different approach is needed to determine the value of this factor. In this paper an experimental method to determine the exact value of the modified slenderness ratio of a built-up compression member by comparing it to the slenderness ratio of a solid column is given. The results are further illustrated using finite element modeling.
El-Mahdy, G.M. Experimental Calibration of Centrally Loaded Built-Up Battened Columns. (2019). Proceedings of the International Colloquium on the Stability and Ductility of Steel Structure (SDSS 2019), Wald & Jandera (Eds.), Prague, Czech Republic, 11-13 September 2019. ISBN 978-0-367-33503-8 pp 394-401.