Conceptual Design And Wind Resistance Reseaech Of The 5000m-Span Suspension Bridge With CFRP Cables

Suspension bridge has the largest spanning ability among all the bridge types owing to its excellent mechanical properties.From the Akashi Kaikyo bridge in Japan (1991m-span) to the planning Messina Strait Bridge of Italy(3300m-span),the record of Ultimate Span of Suspension bridge has been refreshed, and the modern Suspension bridge has the tendency to develop longer and biger.As the traditional material of Suspension bridge cables system, steel cables system were not so suitable for the construction of the super-span Suspension bridge because of its heavy weight.While the new CFRP material has great advantage in the Suspension bridge cables system with its high strength,low density and good corrosion resistance properties.Nowdays the practice of CFRP material in the international bridge engineering are still at the experimental stage, for this reason some exploratory studies of super-span suspension bridge had been doing here.The research started from the structure design of suspension bridge,studying the methods calculating for cables shape and forces.Firstly Deducing the single cable equation and comparing the difference between parabola and catenary equation.Then establishing the elastic catenary equilibrium equation, presenting a accurate method to calculate cables shape precisely, proposing the calculation formulas of the unstressed length and stress of main cable.Writing a Matlab program to get the solution and comparing with finite element software calculation results.This will lay the foundation for the future design.The calculation formulas of the section area of main cable at the state of completed bridge are deduced.Considering the section area of main cable as the controlling factor to compare the differences between CFRP cables and steel cables.The design of a 5000m-main span suspension bridge with CFRP cables is completed with carefully chosen parameters. The Structure Strength, Stiffness and stability of the bridge under 6 different load conditions are testing.The influences of different structural parameters on static behaviors of this suspension bridge which relate to sag-span ratio,mide-side spans ratio, Bridge tower Structures,etc,are analyzed.The first 25 vibration modes and natural frequency of the 5000m-span suspension bridge with CFRP cables are calculated by the finite element method. The influences of different structural parameters on vibration modes and natural frequency of this suspension bridge which relate to sag-span ratio,mide-side spans ratio, stiffening girder structures and stiffness, central buckle,etc,are analyzed.The aerostatic stability of suspension bridge theory is briefly introduced.Then the three-component coefficient and wind field characteristics of separated box girder and ordinary box girder are compared through CFD numerical calculation.The structure three dimensional nonlinear aerostatic methods are programming based on the ANSYS 15.0.The aerostatic stability critical wind speeds of the 2 different suspension bridge girder designs are compared through numerical calculation.The flutter critical wind speeds of the 2 different designs are also calculated and compared.A 5000m-span suspension bridge with steel cables is designed,the wind resistance performance and dynamic properties of it are calculated and compared with the CFRP one.