The Effect of Shear Coexistent with Axial Compression on Transverse Stiffeners in Longitudinally Stiffened Plates

Longitudinally stiffened steel plates are becoming increasingly important in bridge design as the size of new bridges increases. Examples are the steel spans (26ft wide box girders) of the Mumbai Trans Harbour Link, under construction in India, and the deck and towers of the Izmit Bay suspension bridge, recently completed in Turkey. The stability of wide plates with multiple longitudinal stiffeners depends on the transverse stiffeners to restrain the longitudinal stiffeners. The destabilizing actions on the stiffeners include both the longitudinal compression and the in-plane shear. The design methods currently available in design codes account for the longitudinal compression in the plate but do not include the in-plane shear. Therefore, designers do not know if they should either ignore shear coexistent with compression or attempt to account for it.

This paper presents the results of finite element analyses showing the destabilizing effect of shear in addition to compression on the transverse stiffeners of longitudinally stiffened plates. It considers plates with different aspect ratios. The analyses use non-linear geometry with non-linear material properties and the plates are modeled with initial geometrical imperfections. The destabilizing effects of different magnitudes of in-plane shear coexistent with longitudinal compression are compared with the effects calculated using a simple analytical model suitable for use in a design office.

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