Study On Improvement Of Flutter Stability Of Long-span Suspension Bridge During Erection By Eccentric Mass Method

With spans of suspension bridges becoming longer and longer, the stiffness and the damping of structures decrease obviously and the critical wind speed of flutter reducing accordingly.So enhancing flutter stability has become an important task during the design and erection of long-span suspension bridges.A long-span suspension bridge with main span of 1650m—XiHoumenbridge is the project background of this paper.A systematic study of the flutter analysis theories and the method increasing the flutter critical wind speed by the eccentric mass method is studied and analyzed in terms of dealing with the project.The two dimensional and three dimensional flutter analysis method are using by author, the flutter stability of each constructing phase is analyzing by the cyber-program in Matlab.The analytical results indicates that the flutter critical wind speed during mostly constructing phase of the primary project is under flutter testing wind speed, so the requiring of flutter stability can not be satisfied, an effective method is needed to introduce for insuring the security of the structure in wind-resistant during the erecting of the bridge.So the potential improvement in flutter stability of long span suspension bridges by eccentric mass method is discussed, the flutter analysis method based on state space method is introduced in this paper simultaneously, the improvement in flutter stability of the long span suspension bridge is analyzed by two and three dimensional aimed at the eccentric mass method, the influence of different size,position of eccentric mass on flutter stability are analyzed in detail, and the method of wind tunnel test is adopted to validate this method.The analytical results indicate that the eccentric mass method is a significant measure in enhancement of the flutter critical wind velocity during the erecting of suspension bridge.