AbstractStiffened plates (orthotropic plates) are used in many structures, for instance as plate girders and box girders in bridges, in ship hulls, and in bridge decks to minimize the dead load. Used as flanges or part of flanges in larger cross‐sections, stiffened plates develop membrane compression or tension, and in some cases in‐plane shear due to bending or axial actions on the cross‐section. The strength analysis of an orthotropic bridge deck has to take into account both buckling of the stiffened plate as a unit, local buckling of subpanels of the deck plate or the stiffeners, stiffener instability, and effects of transverse loading (e.g. dead load plus traffic load) on the stiffened plate.Adequate rules to determine the capacity of stiffened plates subjected to the combination of axial force and transverse load, as in bridge decks, are scarce or non‐existing in the present Eurocodes for design of stiffened plates and should be developed. An approach applying detailed FE‐analyses will often not be feasible in practical design due to an often weak correlation between the various loads, e.g. dead load, traffic load and loading in horizontal direction (wind), a large number of loading patterns for moving loads, different load combinations and loading levels in adjacent spans, as well as many different cross sections along the bridge.As a pre‐study of the mentioned load combination of axial force and transverse loading it have been simulated a stiffened plate (4 by 5 meter) motivated by the orthotropic deck of a bridge box girder for a suspension bridge. The axial stress was varied from 0 N/mm2 to 250 N/mm2 and combined with application of transverse loading until the stiffened plate collapsed in a flexural buckling mode. The capacity was determined following the provisions in Eurocodes prEN 1993‐1‐1, EN 1993‐1‐5, EN 1993‐1‐7 and the offshore standard DNV‐RP‐C201.It is evident that the modeled typical bridge deck, which is much wider than it is long and has large longitudinal stiffeners, behaves like a beam‐column between the supports. Even if the modeled stiffened plate is made almost quadratic, column‐like behavior prevails, and plate‐like behavior can be neglected.Capacity checks of a stiffened bridge deck, considering a strip of the deck comprising plate and one belonging stiffener, involve a highly mono‐symmetric cross‐section. Capacity should consider yielding both at the plate side and at the stiffener side. The DNV standard does this, and capacity determined from its equations agrees quite well with the FE‐simulations. The design provisions in the new prEN 1993‐1‐1 (Appendix C), which refer to its ordinary beam‐column formulas, must be modified to account for yielding at both sides of the stiffened deck to produce accurate results over the entire range of axial compression and transverse load. When modified, capacity predictions are on the safe side, yielding capacity approximately 70 % of the FE‐predictions.
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Jan 1, 2022
Jørgen Erik Christensen + 6
Open Access
