Long-Term In Situ Performance Investigation of Orthotropic Steel Bridge Deck Strengthened by SPS and RPC Solutions

The development of fatigue cracks in orthotropic steel bridge decks is a problem that bridge engineers are facing and need to solve urgently. A modified overlay is usually used to strengthen an orthotropic steel bridge deck, and the strengthening effect of the modified overlay is the primary focus of attention of this paper. To compare the mechanical property and stability of different strengthening solutions, a simply supported steel box girder bridge was strengthened using the sandwich plate system (SPS) and reactive powder concrete (RPC) solutions. Based on actual bridge data, the authors conducted a 7-year in situ mechanical performance test and follow-up investigation on the service conditions of the orthotropic composite steel bridge deck. Research results show that the mechanical performance and deformation of the longitudinal ribs and decks were both significantly improved. For SPS and PRC, the average stress on longitudinal ribs (decks) has been decreased by 52% (70%) and 81% (95%), respectively. Similarly, the deflection of longitudinal ribs (decks) was improved by 70% (75%) and 82% (86%), respectively. Moreover, no apparent degradation of mechanical performance was observed; the improving effects on the average stress of the SPS and PRC solutions were relatively stable. In addition, the stress and deformation of the SPS steel composite deck were positively correlated with temperature. Furthermore, serious damage in the initial overlay of the SPS solution were observed during the test. Based on a comparative analysis with a case in Germany and finite-element analysis, the effects of ambient temperature, the structure type of the deck, and the thickness of the SPS system should be taken into consideration when the SPS is applied to those bridges built in subtropical or tropical zones.