Real Stiffness and Fatigue Resistance of Stringer-to-Cross-Girder Connection of Riveted Steel Railway Bridges

Steel girder bridges with member decks belong to the most frequently used types of superstructures of old riveted steel railway bridges. During their service life, the bridge deck members are affected by escalating effects of the traffic loads that significantly exceed those for which they were originally designed. As a result, these structures are often subject to the increased effects of fatigue degradation. One of the typical cases of fatigue damage on steel riveted bridges is a fatigue crack in the web of the stringer at the point of its connection to the cross girder. Such a connection used to be considered to transmit the axial and shear forces only, and so no fatigue crack was expected to develop in this detail during the bridge service life. However, the relatively frequent occurrence of fatigue cracks indicates the incorrectness of this assumption. This article is divided into two parts. Firstly, the bending stiffness of the stringer-to-cross-girder connection with different structural arrangements is analysed. Theoretical and experimental analyses of fictitious steel superstructures as well as of a real superstructure of an existing steel riveted bridge were performed to clarify the real stiffness behaviour of this detail. The results of the analyses confirm the assumption of a certain bending stiffness of the observed connection. Subsequently, attention is paid to the fatigue resistance of the riveted stringer-to-cross-girder connection in terms of the use of European standards. The results of fatigue tests performed on specially prepared test samples are presented with the aim to define the fatigue detail category.