Influence of Crossing Cable Arrangement on the Static Performance of Long-Span Three-Tower Cable-Stayed Bridges

Insufficient structural stiffness is a key technical challenge that restricts the increase in span of multi-tower cable-stayed bridges. In order to clarify the application effect of crossing cables in long-span, multi-tower cable-stayed bridges, theoretical analysis and the finite element method were used to study the influence of the cable sag effect on the longitudinal constraint stiffness of crossing cables. The longitudinal constraint stiffness formula of the crossing cable was modified by introducing the equivalent elastic modulus to consider the cable sag effect. Based on the stiffness formula, the influence of the main span, initial stress of the crossing cable, and the ratio of the crossing cable area on its restraining effect was analyzed. The finite element model of a three-tower cable-stayed bridge with main span length of 1000 m and 1500 m is established to verify the accuracy of the formula, and the influence of the number of crossing cables and the tower height on the restraining effect of crossing cables is explored. The research results indicate that as the main span length increases, the location of maximum restraining stiffness of crossing cables moves closer to the mid span; increasing the area of crossing cables connected to the mid tower can effectively suppress the deviation of the tower. In addition, increasing the main span length will reduce the restraining effect of the crossing cables, while changes in the height of the towers do not affect the enhancement effect of the crossing cables on structural rigidity.