Local scour is the major cause of bridge water damage. The sediment in the riverbed around the pier is eroded and transported by water flow, leading to a loss of bridge foundation stability. In this study, a horn-shaped collar was proposed to mitigate local scour around bridge piers. The three design parameters (bottom diameter, vertical height, and curvature shape index) of the horn-shaped collar were studied under clear water condition, and the number of experimental tests was reduced to 25 by using Taguchi’s method. Main effect analysis was used to determine the optimum design parameters for the horn-shaped collar. The results show that the three design parameters have a significant effect on the scour reduction capacity of the horn-shaped collar, with the bottom diameter of the collar making the greatest contribution. The optimum values for the bottom diameter, vertical height, and curvature shape index are 5D, 0.25D, and 4, respectively (D represents the diameter of the pier), and the optimized shape of the horn-shaped collar reduces the maximum scour depth around the pier by 100% compared to the unprotected case. Based on the experimental data, prediction equations are developed for the maximum scour depth protected by a horn-shaped collar.

Hybrid cable-stayed suspension (HCSS) bridges enjoy broad application prospects due to their excellent stability and economic benefits. The mechanical response of the transition section between the two subsystems of this novel bridge type is a common concern in the design and use stages. This paper took the design scheme of an HCSS bridge with a main span of 1440 m as the research object. A global finite element model (FEM) of the example bridge and local finite element models of the transition section were established, and the mechanical performance of the subsystem and components of the transition section was investigated. Moreover, parametric studies were conducted to investigate the influences of varies structural parameters on the mechanical performance of the transition sections of HCSS bridges. The results show that the mechanical behavior suddenly changes significantly at the transition between the cable-stayed section and the suspension section. Performance mutations in the transition section of a HCSS bridge can be improved by changing structural parameters, such as the transition section length, the number of cross cables, the area of the outermost cables, and the distance between the outermost cables and adjacent cables. The present findings may provide a reference for the better understandings and design of HCSS bridges.

The hybrid cable-stayed and suspension (HCSS) bridge is known for its stability and cost-effectiveness, with significant application potential. This study examined the static performance of an HCSS bridge with a 1440 m main span. A finite element model (FEM) was developed to assess key parameters, such as the span-to-rise ratio, cable-to-hanger ratio, pylon stiffness, steel–concrete interface, and cable stiffness. Through FEM analysis and parameter optimization using the zero-order and first-order optimization methods in an ANSYS module, key design variables were optimized. The results show that an inappropriate span-to-rise ratio negatively impacts mid-span girder forces, while increasing the cable-stayed area enhances the overall stiffness. Main cable stiffness plays a crucial role in load-bearing and deformation control. Significant force differences were observed between stay and hanger cables, with axial force in the main girder increasing from the side span to the pylon under dead load. Bending moments in the transition region varied widely under combined loads. Optimizing parameters, such as the span-to-rise and cable-to-hanger ratios, significantly improved the mechanical performance of HCSS bridges, offering valuable insights for future designs.