PSI - Issue 38

Yuichi Shiraishi et al. / Procedia Structural Integrity 38 (2022) 588–595 Author name / Structural Integrity Procedia 00 (2021) 000 – 000

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1. Introduction Orthotropic steel decks (OSDs) have a problem on fatigue durability, while OSDs have advantages of light weight and short construction time. Then, a research project on improving fatigue durability of OSDs had been set up in 2017. In the project, countermeasures against fatigue cracking in OSDs have been investigated and verified by Finite Element Analyses, fatigue tests and stress measurements in actual bridges [Sakano (2020)]. The effective countermeasure against fatigue cracking at welded joints between a deck plate and trough ribs have been already proposed [Mizogami et al. (2017)]. In this study, focusing on fatigue cracking at welded joints between trough ribs and cross ribs [Hanshin Expressway (2012) and Hattori et al. (2007)], countermeasures for existing structures and renewal or newly constructed structures are proposed and verified through fatigue tests using a large specimen with the same size as actual OSD details. 2. Experimental procedure 2.1. Specimen and retrofitting method Fig. 1 shows configurations and dimensions of the specimen and loading areas. The specimen had two trough ribs, three cross ribs and two main girders. Dimensions of the specimen was 4.3m in length, 1.4m in width and 0.9m in height. Trough ribs in the specimen were an existing structure (U1) and a newly structure (U2). In this specimen, diaphragms were set in each trough rib at a distance of 300mm at east side from a central cross rib for investigating the effect of diaphragms. Fig. 2 shows details of a connection between trough ribs and a cross rib. Welded joints in the existing structure (U1) were retrofitted angles which were spliced to the undersurface of the trough rib by Thread Rolling Screw (TRS). TRS is a one- side bolt for bearing joint. TRS doesn’t need to check inner friction surface of the trough rib,

Fig. 1. configurations and dimensions of the specimen and loading areas