Fatigue properties of OSD in large cantilever cable-stayed bridge on highway-railway layer

Abstract

To enhance the understanding of fatigue issues in orthotropic steel deck (OSD) bridges with cantilevered steel-box girders on highway–railway layers and ensure the fatigue life of similar bridges, this study focused on the OSD fatigue characteristics of the Jinhai Bridge, the world's widest dual-use–cable-stayed bridge for road and railway transport. The fatigue-stress distribution characteristics and variation rules were investigated using a full-scale fatigue test model. Four U-ribs were subjected to four million loading test cycles, and the OSD fatigue performance was evaluated using the nominal stress method. The results indicated that the stress-influence range of the crossbeam U-rib in a large cantilever steel box girder was approximately nine U-ribs wide and three crossbeams long, significantly exceeding that of a conventional closed-box steel girder. The stress difference in the crossbeam opening bottom-edge detail in the box girder with and without a cantilever was 85.4%. Along the transverse bridge, the most unfavorable stress amplitude difference among similar fatigue details in different regions reached 57%. After 4 million cycles, the crack length was 90 mm. The fatigue cracks had a minimal effect on the overall deformation performance of the model. Combining the traffic volume statistical data and damage accumulation, the estimated fatigue life of the crossbeam opening detail was 103.55 years. According to JTG-D64–2015, this satisfies the recommended fatigue design life requirement of 100 years for the crossbeam opening details of large cantilever steel box girders. However, the economic development trends and increasing traffic volumes necessitate further research.