Study On Mechanical Behavior And Stability Of A New Type Long-Span Railway Steel Truss Arch Bridge

The DPSD Bridge is a railway steel truss arch bridge with double arch ribs. The span arrangement is (85.75+286+85.75) m. The upper arch rib extends to the side pier, and the lower one is supported on the middle main pier. This kind of bridge structure has never been used and the mechanical behavior is complicated. In this paper, the deformation and mechanical behavior of the whole bridge, the mechanical behavior of the key joint G11and the stability of the whole bridge were studied. Main work and achievements are listed below:1.3D finite element model of the whole bridge was established by adopting Space Plate-Beam method. The deformation and mechanical characteristics of the bridge under dead load, worst-case of living load, additional forces and loads combination were studied. The results show that the stiffness and strength of the bridge meet the requirements, the working condition is generally reasonable.2. Based on global analysis, compared with other key parts of the main truss, the biggest joint G11was selected to be the object of local detailed analysis. G11is located at the junction of the lower arch rib and the lower chord, it has the most number of members and the internal force in these members is very large. The mechanical behavior of G11is very complicated.3. Considering all details of structure, the refined finite element model of G11was established. The mechanical behavior of G11under various working conditions was studied. The results show that, in spite of the stress centralization, the maximum stresses of all members do not exceed the yield stress. The design of the G11joint is reasonable.4. The global stability of the bridge in the completion state with or without train were studied, the results show that the train load has great influence on the global stability of the bridge, while across-wind load has little influence. The first order buckling mode was controlled by the out-plane instability of longitudinal bracing rods, while the global instability didn’t happen until higher order buckling mode. The stability safety coefficient of the whole bridge is greater than9, and the whole bridge has a good stability characteristics.The results of this article provide design basis for DPSD Bridge, and also provide references for other similar bridges. This paper has99graphs,43tables and63references.