Analytical Shape-Finding of the Three-Dimensional Wind-Resistant Rope System of a Suspension Bridge | Journal of Bridge Engineering | Vol 27, No 10

AbstractWind-resistant rope systems (WRRS) consisting of wind guys (WGs) and ties are widely used in suspension bridges to improve their stability. Shape-finding of WGs is quite problematic due to their three-dimensional (3D) form and differs from that of the main cable. This study analyzed a WRRS with the 3D WG and obliquely intersecting ties. An analytical algorithm for the WG shape-finding in this system was developed and applied to five cases with different sets of known and unknown parameters. The recurrent relations between different parameters, namely, the horizontal force component of the WG, the deflection angle of the vertical plane where the catenary was located, and parameters of the shape equation, were derived based on the static equilibrium between the nodes, reducing the number of unknown quantities. The WG shapes were derived for various cases according to different governing conditions. The feasibility of the proposed algorithm was proved for the particular case study of a pedestrian suspension bridge, and cross-verification was provided for four cases. Besides, the finite-element method was employed to verify the accuracy of the proposed analytical approach. The calculation results revealed the following patterns of the horizontal force components in each catenary segment of the WG: they reached their maximum values at both ends of the WG, gradually decreasing from the ends to the middle and attained their minimum in the middle catenary segment of the WG. All WG nodes were located below the inclined plane passing through the anchor points at both ends and the middle node of the WG.Practical ApplicationsPedestrian suspension bridges are in a stage of rapid development and usually have relatively narrow decks with lower stiffness, which may cause a decrease in the wind-resistant performance especially when these bridges are located in valleys with high wind speeds. In this situation, the application of wind-resistant rope systems may be a great potential approach to increase the overall stiffness and improve the wind-resistant performance of the bridge. In addition, wind-resistant rope systems will be a highly feasible reinforcement measure for old suspension bridges with cumulatively fatigue damaged cables or poor performance under wind load. However, no matter how the wind-resistant rope systems are applied as the part of the structures, it is inseparable from refined shape-finding analysis of the wind-resistant rope system.

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