Competing mechanism between vertical stiffness and anti-slip safety in double-cable multi-span suspension bridges

Double-cable multi-span suspension bridges (double-cable bridges) have great development prospects in long-span bridge engineering. The vertical stiffness of the bridge and the anti-slip safety between the cable and saddle are the two primary competing factors governing the preliminary design of double-cable bridges. It is essential to study the competing mechanism between these two factors to determine reasonable parameters for designing sustainable double-cable bridges. In this study, the deflection-span ratio and anti-slip safety coefficient were adopted as indices to evaluate the vertical stiffness and anti-slip safety, respectively. Finite-element analysis was performed to investigate the influence of the main design parameters on the relationship between the deflection-span ratio and anti-slip safety coefficient and to clarify the competing mechanism between these two factors. Finally, we propose some recommendations for the preliminary design of double-cable bridges. The results of our study reveal that increasing the bending stiffness of the middle tower, increasing the constant load distribution ratio, or installing vertical friction plates in the top sub-saddle are useful in expanding the application scope of double-cable bridges. This study provides new insights into the competing mechanism between the vertical stiffness and anti-slip safety of double-cable bridges.