Analysis of the Vertical Bearing Performance of a Double-Layer Steel Truss Bridge with Arched Stiffening Chords

Based on the actual project of the Xi'an Metro Line 10 combined road-rail bridge crossing the Weihe River, the mechanical properties of a double-layer steel truss bridge with arched stiffening chords were investigated by using the ABAQUS finite element analysis software, a model focusing on the middle three spans with arched stiffening chords was established considering boundary conditions. Vertical load simulations were compared with the results from scaled model tests. The comparisons showed that the load-displacement and load-strain curves in the elastic stage matched well, confirming the reliability of the simulation method. A parametric analysis was then conducted to examine the effects of the number and arrangement of vertical rods on the vertical bearing performance of the bridge. The results indicated that adjusting the vertical rod arrangement had minimal impact on mid-span displacements and web member strains above the supports, but slightly increased the stress in the top chord at the supports and significantly increased stress in the stiffening chord members at the highest point. Arranging one vertical rod above each joint under the stiffening chord increased the steel consumption, but it could effectively control the structural deformation and member strain, and provide a uniform and aesthetically pleasing design. This arrangement is therefore recommended.