Experimental Study Of Large-scale Full Bridge Aeroelastic Model In Natural Wind

The increasing span of bridge structure also brings many problems,such as the decrease of structural stiffness and damping,the gentler system and the more significant wind-induced vibration.Wind resistance performance of bridge has gradually become one of the important indexes to ensure the reliability and safety of large bridge structure.By weighing the advantages and disadvantages of the main research methods of bridge wind engineering,the research team creatively proposed the outdoor experimental base for Bridge Wind Engineering(OEBBWE),and carried out large-scale full bridge aeroelastic model test in natural wind:(1)By comparing the traditional research methods of wind engineering and weighing the advantages and disadvantages of various methods,the research team proposed a new idea of outdoor test base of bridge wind engineering,and compared the advantages and disadvantages of this research method and the traditional research methods of bridge wind engineering in detail.The process of making aeroelastic model of Tacoma bridge is introduced in detail,and the design principles of safety,applicability,durability and economy are given;(2)Two identification methods of structural modal parameters,frequency domain decomposition method and time-frequency analysis method,are introduced.The process of traditional frequency domain decomposition method to identify modal parameters is given,and the problems of this method are discussed,such as the identification error of damping ratio is large,it is difficult to deal with dense modes,and it is difficult to identify time-varying systems.In the time-frequency analysis method,the idea of sliding window threshold de-noising and moving average technology are used to solve the iterative error and over envelope problem in the empirical envelope method.Through the parameter identification analysis of several examples,it is proved that the proposed method has good anti noise performance and high recognition accuracy.(3)This paper introduces the static test of the aeroelastic model of the whole bridge,then establishes the finite element model of the aeroelastic model of the whole bridge,compares the static and modal parameter errors between the finite element model and the actual aeroelastic model of the whole bridge,and analyzes the new structure sensitivity.Finally,the finite element model correction theory and steady-state genetic algorithm are introduced,and the finite element model of the whole bridge is modified.(4)It is found that the thermal effect is the main reason for the formation of daily strong typhoon.It is found that the selection of reference sample and time interval has little influence on run test method,but great influence on reverse test method,and there are some nonstationary characteristics in the measured wind field;The stationary model is difficult to reflect the difference of turbulence intensity at different times in the same time interval,while the nonstationary model has rich non-stationary components,which can well reflect the difference of turbulence intensity at any two times,and more truly reflect the turbulence characteristics of natural wind field.(5)Through the long-term vibration response and wind field detection of the bridge model,all vortex vibration phenomena of the bridge model are summarized,and the influencing factors of the typical vortex vibration phenomenon on January 8,2021 are analyzed in detail.The results show that the vortex vibration of the bridge model mostly occurs in the low wind speed area,and the wind deflection angle of the main beam(the angle between the wind direction and the vertical line of the main beam axis)is 60° Vortex vibration may occur within the range,but more than 60° No vortex vibration was observed.