斜拉桥Π型开口主梁断面抖振性能比选

摘要

为获得斜拉桥Π型开口主梁断面在脉动风作用下的合理气动外形,在风洞试验的基础上进行了抖振性能比选.首先,以一主跨300 m的斜拉桥为原型,设计了3组不同的Π型主梁断面;其次,进行了节段模型测力、测振风洞试验,获得Π型主梁断面在不同风攻角下的静风三分力系数和颤振导数等气动力参数;最后,以上述气动力参数为基础,采用同时考虑自激力和抖振力的计算模型对不同Π型主梁断面的抖振性能进行比选分析.结果表明:不同外形主梁的抖振响应不同,通过改变外形可以改变Π型主梁在任一自由度上的抖振性能,但对竖向、侧向和扭转自由度的影响往往很难同时达到最优.Π型主梁断面合理气动外形的选择,应根据斜拉桥受力特性,综合考虑颤振、涡振和抖振性能后确定.%In order to obtain reasonable aerodynamic shape of Π shaped bridge decks,the buffeting performances comparison of a cable-stayed bridge was conducted based on wind tunnel tests.Firstly,three different types of Π shaped bridge decks were designed based on one real cable-stayed bridge with a main span of 300 m.Secondly,force balance and vibration sectional model wind tunnel tests were carried out to obtain aerodynamic parameters under different wind attack angles.The aerodynamic parameters include three-component static wind loading coefficients,flutter derivatives,etc.Finally,three types of Π shaped bridge decks' buffeting performances were compared and analyzed by considering the aeroelastic and buffeting forces.The results show that buffeting responses of the bridge with different Π shaped decks are different from each other.Buffeting responses in any one freedom could be changed when changing bridge deck shape.However,the optimal influences in vertical,lateral and torsional directions could not be achieved at the same condition.Reasonable aerodynamic shape selection of Π shaped bridge decks should consider the mechanical characteristics and the performances of flutter,vortex and buffeting.