Patch loading resistance of slender plate girders with longitudinal stiffeners

It is commonly known that the patch loading resistance model of the EN1993-1-5 has a relative large scatter, and it can lead to significant underestimation of the patch loading resistance in case of slender plate girders with longitudinal stiffeners. Large number of previous investigations studied the structural behavior of the stiffened girders subjected to concentrated transverse force. Although a reliable and simple design method is not available in the international literature. The main part of these investigations focus on girders with one longitudinal stiffener, however in the bridge design praxis, usually more stiffeners are applied on the web. For these structures the applicability of the improved design methods is not proved. It is also known, that the current design method of the EN1993-1-5 does not consider the location of the longitudinal stiffener properly. The focus of the current paper is on the investigation of the patch loading resistance of longitudinally stiffened slender web girders and an enhanced design method development. Based on a large number of numerical simulations the structural behavior is studied and failure modes are classified. The effect of each geometrical parameter on the patch loading resistance is investigated and an improved design method is developed, which is consistent with the design philosophy and safety requirements of the EN1993-1-5 standard.