Parameters analysis for assistant cables of system for transient main cable and catwalk of Long-Span Suspension Bridge at construction stages

摘要

On the basis of static, dynamic and transient analysis for the prestressing cable structures, the parameters to control the vibration of the system for transient main cables and catwalk of some long-span suspension bridge at the construction stages with the assistant cables are investigated adopting the method of the finite element considering the geometry nonlinearity. The review and prospect to control vibration with assistant cables are summarized, the finite element modeling of the system for transient main cables and catwalk is established, and the influence of the position of the assistant cables, disposed fashion and the tensile forces upon the critical frequencies of the system for transient main cables and catwalk is researched. At the same time, the effect of the damp and the tensile forces of the assistant cables on the equivalent damping ratio of the system for transient main cables and catwalk inside and outside the plane is studied and the effect to control the vibration of the system is analysed. In the end, the influence of the transformation for the tensile forces about assistant cables upon those of the transient main cables and catwalk is also investigated. Results show that, to increase the critical frequencies of the system, the assistant cables should be laid vertically with the main cables and be located in interim span or between the tower and interim span, and to increase the amount of the assistant cables can increase the critical frequencies ,and to increase the rigidities of the assistant cables can improve the ones of the transient main cables but decrease the anti-torsion ability of the catwalks, and to increase the damp of the assistant cables can improve the vibration of the transient main cables inside and outside the plane but the result is little outside the plane, and in addition the effect of the rigidities of the assistant cables is larger outside the plane but is little inside the plane. The results also show that the influence of the change of the tensile forces for the assistant cables upon those of the transient main cables and catwalk is very little.