Interaction of Buckling Modes for Cellular Steel Beams Under Flexure.

Steel beams with web openings are extensively used in commercial structures because of their advantages in saving headroom and for providing a passage for utilities like air ducts, water pipes, etc. Design guidelines for such beams are provided by the EuroCode3 and by AISC design guide. The Indian Standard does not provide the design guides and thus an attempt has been made in this paper to utilize the approach for common beams given in IS800:2007 to obtain design bending strength for cellular beams. Finite element analysis has been carried out to obtain predicted values of bending strength of cellular beams. In order to validate the finite element model developed for this study, few examples of cellular beams were selected from literature and the results were compared. Ultimate load at failure, mid-span displacement and modes of failure were the parameters used to validate the developed model. Beam models with three grades of steel (E250, E350 and E450) and varying slenderness values covering section categories from plastic to semi-compact have been analyzed. It was found that while the specifications can conservatively predict the bending strength for E250 grade steel, they were found to be quite unconservative for higher grades and specially for the beams having semi-compact webs. [ABSTRACT FROM AUTHOR]