Research On Aerodynamic Effect Of Cable-stayed Bridge With CFRP Cables

With the continuous progress of Carbon Fiber Reinforced Polymer/Plastic(CFRP)in the engineering research,the application of CFRP as cable material in cable-stayed bridges has become a new direction for the development of bridge engineering.Compared with the traditional steel cable,the CFRP cable has higher bearing efficiency and stronger corrosion resistance,which can overcome the limitations of the cable-stayed bridge to the development of lightweight and large span.However,the weight of CFRP is much lower than that of steel.The application of the CFRP will cause the overall rigidity of the bridge structure to decrease,and its sensitivity to wind load is indistinct.This paper takes the Yuejiang Bridge in Zhaoqing City of Guangdong Province as the engineering background,replaces the steel with the CFRP as the cable material based on the principle of equal axial strength substitution.By comprehensively comparing the flutter stability and static wind nonlinear stability of the two types of cable-stayed bridges,and the wind-induced vibration response of two types of cables,the wind resistance performance of carbon fiber cable-stayed bridges is explored.The specific work and related conclusions are as follows:(1)The finite element software ANSYS is used to establish the full-bridge model of two types of cables,and the dynamic characteristics of two types of cable-stayed bridges is calculated to solve the critical flutter wind speed.The results show that the first fifteen vibrational frequencies of the CFRP cable-stayed bridge is reduced.For the two types of cable-stayed bridges,the critical wind speed of flutter is not much different;(2)FLUENT is used to solve the static three-component force coefficients of the main girder under different wind attack angles.Based on the research theory of the nonlinear aerostatic stability of the bridge,and the nonlinear influences of the static three-component coefficient and the wind load are introduced to compile the critical wind speed optimization solving program for bridge static wind instability by ANSYS;(3)Through the above procedure,the critical wind speeds for static wind instability of two types of cable-stayed bridges are solved.The results show that the static wind nonlinear deformation characteristics of carbon fiber cable-stayed bridges and steel cable stayed bridges are the same,and there is no significant deformation or sudden divergence.The critical wind speed is relatively close;(4)The Kaimal horizontal wind spectrum is selected as the fluctuating wind spectrum density function.Based on the AR mathematical model in the linear phase filter method,MATLAB is used to compile the relevant program to simulate the horizontal fluctuating wind speed history around the cable.According to the simulation results,the turbulence intensity formula is fitted,and the turbulence parameters of the flow field are successively solved as the initial conditions for subsequent wind field simulation;(5)The CFD numerical method was used to simulate the wind-induced vibration of the two types of cables in two types of operating conditions.The simulation results showed that the flow field distribution of them was nearly the same,but the negative pressures of the upper and lower sides of the CFRP cable were larger.In the wind-induced vibration performance,the vibration frequency of the CFRP cable is higher than that of the steel cable,and the amplitude is reduced.