Investigation On Aerodynamic Interference Effects Of Wind-induced Vibration Of Continuous Rigid Frame Parallel Bridge

Recently,the transportation industry in our country has developed rapidly.The continuous rigid frame parallel bridge has become one of the commonly used bridge types.As the continuous rigid frame parallel bridge develops toward a large span and a gentle direction,its wind resistance problem is increasingly prominent.The continuous rigid frame parallel bridge has poor wind resistance under the maximum cantilever state in the construction stage,and it will produce complex aerodynamic interference effects when facing the inflow.The wind-resistant design specifications currently in use only consider the response of the isolated structure and ignore the interference of the surrounding structure.In view of this,this paper takes a continuous rigid frame bridge as an engineering example to study the aerodynamic interference effect of wind-induced vibration of continuous rigid frame parallel bridge.The main work and achievements of this paper are:(1)Through the aeroelastic model wind tunnel test,the wind-induced vibration displacement responses of the upper and lower reaches of the parallel bridge are obtained with different clearances,wind direction angles,wind angles of attack,and misalignment and height difference.Then analyzing the vertical displacement response of the parallel bridge under 66 working conditions,and then get the effects of various disturbance factors on the aerodynamic interference effect of the parallel bridge wind-induced vibration.The results show that compared with the single bridge,the vertical vibration responses of the main girder of the parallel bridge are reduced to different extents.The net spacing,wind direction angle,wind angle of attack,and the misalignment and height difference of the bridge have an effect on the wind-induced vibration interference effect of the parallel bridge.There is a significant correlation between the interference factors.(2)Considering the structural form and the pulsating wind field characteristics of the continuous rigid frame parallel bridge,simplify the spatial pulsating wind field of the continuous rigid frame parallel bridge,and then simulate the spatial pulsating wind field of the continuous rigid frame parallel bridge by the harmonic superposition method.(3)Based on the ANSYS finite element analysis software the finite element model of the maximum double cantilever state of continuous rigid frame single bridge and parallel bridge was established.The wind load is time domain processing through the Davenport quasi-steady theory.The effects of self-excitation on the wind-induced response of the bridge structure are considered by introducing an aerodynamic stiffness matrix and an aerodynamic damping matrix.Then,using the ANSYS finite element software to analyze the buffeting response time domain of the maximum double cantilever state of the continuous rigid frame single bridge and parallel bridge.After the data is processed,the influence of the interference effect on the buffeting response of single and parallel bridges under different working conditions is obtained.The results show that compared with the single bridge,the net spacing,angle of attack and height difference of the upstream main beam have little effect on the buffeting displacement response of the main girder of the continuous rigid frame parallel bridge,and have a greater impact on the buffeting response of the downstream main beam.The influence of the disturbance effect on the lateral displacement of the buffeting of the main beam is mainly the occlusion effect,and the response to the vertical displacement of the buffeting of the main beam is mainly the amplification effect.In summary,the influence of the aerodynamic interference effect on the windinduced vibration response of the parallel bridge should not be ignored.In the actual engineering design,it is necessary to consider the adverse effects of the interference effect on the bridge structure.