This article presents some observations related to the phenomenon that occurs when transversally and longitudinally stiffened steel plate girders are subjected to patch loading. The failure mechanism differs considerably for the particular structural case of girders with largely spaced transverse stiffeners, which have been studied thoroughly in last decades. Steel plate girders with closely spaced stiffeners are occasionally found in bridge design and for such cases, the current EN1993-1-5 rules underestimate the strength of the webs to transverse forces. Research work on girders with closely spaced transverse stiffeners is available but for such cases, the web plates are longitudinally unstiffened. Some comparisons between the results obtained and those provided by EN1993-1-5 are discussed. Preliminary results suggest that the resistance of densely stiffened steel girders (both transversally and longitudinally) must be studied and subsequently revised accordingly. In addition, it is pointed out that a certain degree of imperfection sensitivity is inferred from the results. Further studies on this topic are necessary.

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