Estimation of rotation capacity of monosymmetric I-beams

Monosymmetric I-beams have their specific advantages over doubly symmetric I-beams, although doubly symmetric I-beams are the most commonly produced, used and code referenced section. The existing design literature and codes of practice fail to provide methods to properly account for effects arising from monosymmetry of cross sections. Taking inspiration from the statistical parameter of skewness, we define the standardized third moment of area of a cross section (Sk). Based on data presented by Gioncu & Petcu (1997b) we can show that there is a linear relationship between standardized third moment of area of a section and its rotation capacity; the rotation capacity of a mono-symmetric I-beam (R_x ) is R_sym (1 + k[Sk] _X ), where R_sym is the rotation capacity of the doubly symmetric counterpart of the monosymmetric section X and k is a proportionality constant. This relationship can be explained considering the strain distribution across the critical section of an I-beam.