Accordion Effect on Flexural Resistance of Slender Flange Corrugated-Web Steel I-Girders

Plate girders, renowned for their structural efficiency and design flexibility, have been widely used in diverse civil engineering applications for efficient load-bearing. However, replacing the conventional flat web with a corrugated web enhances shear buckling resistance while introducing the accordion effect and thus reducing their flexural resistance compared with flat-web girders. This study presents an analytical formulation for the moment resistance of slender flange corrugated web girders (CWGs) based on effective compression-flange width, specifically addressing the accordion effect. Finite element modeling methodology was adopted to examine the flexural behavior of slender flange CWGs. A comprehensive parametric study investigated the nonlinear flexural behavior dependency for various girder geometry parameters under pure bending. The finite element analysis results formed the basis for deriving a moment-resistance formulation, which employs an amplification factor to account for decreased moment capacity. The proposed design model was validated on a database of 34 test results from the literature, further affirming its efficacy. Although the proposed model provides a simplified representation of the accordion effect in CWGs—potentially leading to cost reductions in girder design and the development of relevant design specifications—its applicability to typical girders under both moment and shear in general and for girders subject to negative moments together with larger shear in particular, should be further studied.