Research On Aerodynamic Characteristics And Wind-Induced Buffeting Response Of Main Girder Of Long-span Pedestrian Suspension Bridge

Suspension bridge has super span capacity,good seismic performance,clear force and beautiful shape,so it has become the first choice for long-span bridges.Compared with common highway and railway suspension bridges,pedestrian suspension bridges have smaller width-span ratio,greater flexibility and more sensitive to wind load.Wind-induced vibration has become a controlling factor in the design of this kind of bridges.In this paper,based on the engineering background of a suspension bridge,the aerodynamic shape,surface wind load and wind-induced buffeting response characteristics of the main girder of the suspension bridge are studied systematically with the help of computational fluid dynamics numerical simulation software,MATLAB mathematical analysis software and finite element analysis software.The main contents are as follows:(1)According to the structural form of the main beam of the long-span pedestrian suspension bridge in the design scheme,the three-component force coefficients of the cross section at different positions of the main beam are calculated by using the computational fluid dynamics numerical simulation software FLUENT,and seven kinds of wind attack angles are taken into account.According to the calculation results,the aerodynamic performance of the structure is discussed.On this basis,after adding sharp corner nozzle and fillet nozzle at both ends of the main beam,the aerodynamic performance of the main beam is analyzed,and the aerodynamic parameters,wind pressure distribution and velocity distribution of the three cross sections under different wind attack angles are compared.it is found that the cross section of the main beam has good aerodynamic performance after adding fillet nozzles at both ends of the main beam.(2)According to the characteristics of natural wind and based on the basic principle of linear filtering method,the time history of fluctuating wind speed at different positions of the main beam is simulated by MATLAB software,and the time history of fluctuating wind speed in horizontal bridge direction and vertical bridge direction is obtained.The simulated wind speed time history is converted into wind speed spectrum,and then compared with the target spectrum,it is found that the two are in good agreement with each other.It shows that the wind speed time history at different positions of the main beam can be used to analyze the wind-induced buffeting response of the structure.(3)Based on(1)the aerodynamic parameters of the main beam and(2)the wind load at different positions of the main beam,the finite element model of the long-span pedestrian suspension bridge is established by using ANSYS software,and the displacement response of the main beam structure is calculated,and the calculation results are analyzed.It is found that the main beam is mainly vertical deformation under wind load,and the transverse and torsional deformation are not obvious.