ABSTRACT
Orthotropic steel decks (OSDs) are used for new bridge decks and replacement decks of highway bridges. An OSD includes various welded connections. This paper focuses on rib-to-floor beam (RFB) connections with emphasis on their fatigue performance. The bridge superstructure affects the fatigue stresses in RFB connections. Independent OSD floor beams that are not supported or restrained by other transverse members in the bridge are common for new bridge applications. Restrained OSD floor beams that are supported and restrained by other transverse members in the bridge are common for deck replacement applications. When the OSD floor beam is supported by an existing transverse floor truss (or beam), the fatigue stresses at the RFB connection from in-plane loading are reduced. However, when the OSD floor beam is restrained by the existing floor truss, the fatigue stresses at the RFB connection from out-of-plane loading are increased. Thus, for deck replacement applications, a stress-relieving cut-out is often used in the OSD floor beam web to allow the ribs to rotate more freely under out-of-plane loading. An “extended cut-out” RFB connection has been used extensively in deck replacement applications in the US. The extended cut-out RFB connection often exhibits good fatigue performance, but this type of connection can be labor intensive to fabricate. This paper presents research on a new RFB connection for deck replacement applications with a “slit” cut-out completely within the OSD floor beam web that allows the rib to rotate, and is easier to fabricate than the extended cut-out RFB connection.
