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Determining a reasonable main cable curve is the foundation of suspension bridge design, and the accuracy and efficiency of the curve-finding problem are key to the design of a suspension bridge. To accurately obtain the completed curve of a main cable, force equations, which are nonlinear equations, need to be solved. In this study, the improved particle swarm optimization (IPSO) algorithm with inertia weight is presented to solve these nonlinear equations. Then, taking a double-tower three-span steel-box girder suspension bridge as the research background, the accuracy and efficiency of the IPSO method in finding the main cable curve are studied and then compared with those of the N-R iteration method and the finite element method (FEM). The results show that the proposed IPSO method has a high accuracy and a fast computing speed. Furthermore, the convergence under different bridge parameters is discussed, which demonstrates that the IPSO method has a strong adaptability. [ABSTRACT FROM AUTHOR]

The main goal of this paper is to explore the mechanism of vortex-induced vibration (VIV) of a streamlined box girder from the perspective of flow field and pressure distribution. In this paper, using the computational fluid dynamic method, the VIV performance of fluid under specific working conditions is simulated and analyzed, especially the distribution and evolution laws of vortex structures in the whole process of VIV are studied in depth. Based on the analysis of the flow field distribution, the corresponding relationship between vortex structures and vortex-induced pressures (VIPs) is discussed. The results demonstrate that the primary cause of VIV for streamlined box girders at large attack angles is the circulation process of the massive vortex structures production and dissipation on the upper surface, rather than the alternate shedding of symmetrical vortex pairs. When vortex structures remain stable, negative VIPs rise in absolute value, negative VIPs occur when vortex structures move backward, and positive VIPs increase when vortex structures fall off. [ABSTRACT FROM AUTHOR]