Buffeting Response Analysis Of Long Span Cable-stayed And Suspension Cooperative System Bridge In Time Domain Under The Combined Action Of Wind And Wave

With the development of science and engineering technology,China’s bridge construction has made a great breakthrough.The span of the bridge is constantly being refreshed,while the resistance of the bridge to the complex natural environment is becoming stronger during the construction and operation stage,among which the long-span sea crossing bridge is one of the representatives.Long-span bridges with cable-stayed bridge or suspension bridge,cablestayed bridge and suspension bridge can be collectively referred to as bridge cable system,the former’s stiffness is bigger,wind resistance stability is better,while the latter has larger spanning capacity,less construction difficulty.However,the cable-stayed and suspension cooperative system bridge can combine the advantages of both,has more advantages in the construction of cross-sea bridges in our country.Compared with cable-stayed and suspension cooperative system bridge and cable-stayed bridge,suspension bridge,cable-stayed suspension cooperative system bridge is different in load distribution and force transmission path.Especially in the complex environment under the combined action of wind and wave,its dynamic response problems are more prominent.Therefore,it is necessary to study the dynamic response of long-span cable-stayed and suspension cooperative system bridge under the combined action of wind and wave.Buffeting is the vibration with high frequency in windinduced vibration of long-span bridges.The buffeting response of a bridge under the combined action of wind and wave needs to consider the coupling effect of wind and wave field.In this paper,a super-long-span highway-railway cable-stayed and suspension cooperative system bridge is taken as an engineering example,whose buffeting response under the combined action of wind and wave was studied.The main research contents include:(1)According to the data of hydrology stations near the bridge site,the wave parameters of this study were formulated,and a numerical flume was established in the fluid computing software FLOW-3D to simulate the wave forces on the composite foundation under the cablestayed suspension bridge.(2)The basic parameters of the wind field of the bridge were determined according to the meteorological data of the bridge site.After simplifying the three-dimensional wind field of the cable-stayed and suspension cooperative system bridge,the harmonic synthesis method was used to realize the simulation of the fluctuating wind field of the bridge.The aerodynamic force coefficients of the split three-box deck in wind-wave coupled field were measured by wind tunnel and wave trough test,and the aerodynamic force coefficients of the main tower,the auxiliary pier and the main cable were calculated by CFD numerical simulation.(3)Based on the large finite element software ANSYS,the whole bridge finite element model of the cable-stayed and suspension cooperative system bridge was established,and its dynamic characteristics were solved.Then the buffeting force and aerodynamic self-excited force are time-domain based on the aerodynamic coefficients obtained in the wind-wave coupling field and CFD numerical simulation,and are loaded together with the static wind load and wave load to the corresponding nodes of the bridge finite model for buffeting response analysis.(4)The buffeting response difference of the bridge under the action of wind-only,waveonly and wind-wave is analyzed,and it is found that the main beam is mainly transverse bending,and its resistance competence to vertical bending and torsion is stronger.The main beam is mainly affected by wind field,and the main tower is mainly affected by wave field.(5)The buffeting displacement responses of bridge under the combined action of different wave types and wind are compared,and it is found that the displacement response of bridge under the combined action of random wave and wind is larger.The effect of wave height(effective wave height)on the buffeting displacement response of bridge is studied.It is found that the transverse and torsional displacement responses of main beam are greatly affected by wave height,while the vertical displacement response is less affected by wave height.The buffeting displacement response of the main beam is analyzed when the average value of the peak value,the average value of the whole value and the average value of the valley value of the aerodynamic force of the main beam is taken respectively.It is found that different values of aerodynamic coefficients have less influence on the transverse displacement response of the main beam,but more influence on the vertical and torsional displacement response of the main beam.