Study On Flutter Stability Of Bridge With Eccentric Mass Structure

Suspension bridge has advantages such as large span,material saving and light weight,but it also has the problems such as low stiffness and damping,and sensitivity to wind-induced vibration,the flutter problem with divergent instability in the wind-induced vibration of bridges has always been an important topic.The research on the flutter of eccentric mass bridge section is not only meaningful for completely separated double-box girder bridges,bridges with mass eccentricity in construction,bridges with asymmetric traffic or accessory,but also as a way to improve the critical flutter wind speed.Based on the Great Belt Bridge located in Denmark,the study on the influence of eccentric mass on the flutter critical wind speed is carried out in this paper.The research focuses on the two-degree-of-freedom two-dimensional bridge section model of vertical and torsion.The research content includes the following three parts:(1)In this paper,on the basis of ANSYS FLUENT software,Newmark-? method is embedded into UDF to solve mass center motion equations for the bridge with eccentric mass at each time step,transfer the kinetic parameters which was obtained to the bridge section model and free vibration fluid-structure interaction was realized in the way of dynamic mesh.The UDF written by author was used to carry out a numerical simulation study on the influence of different mass eccentricity distances on the flutter critical wind speed of bridge at 0° and ±3° wind attack angle.In order to verify the reliability of the research method in this paper,program verification,grid independence and reliability verification,as well as comparison verification with other scholars and the wind tunnel test of this paper under the same working condition of flutter critical wind speed were conducted.(2)Using the method of wind tunnel test,the flutter critical wind speed measurement of the bridge section model with different eccentric mass placement distances on the windward side at 0° and ±3° wind attack angle was carried out,the influence of windward additional eccentric mass distance and wind attack angle on the critical flutter wind speed of bridge is discussed.(3)By comparing the wind tunnel test results of the critical flutter wind speed of the bridge section model with different size of additional eccentric mass at the windward side at 0° wind attack angle,the effect of the windward additional eccentric mass on the flutter critical wind speed of bridge is discussed.The wind tunnel test was carried out by placing additional eccentric mass on the downwind side to study the effect of eccentric mass at downwind side on flutter stability,and summarize the unfavorable conditions in the analysis of the flutter stability of the mass eccentric bridge structure.