三线合一钢箱桁悬索桥颤振性能风洞试验研究

Wind Tunnel Test Study of Flutter Performance of a ThreeLine Steel Box and Truss Girder Suspension Bridge

某三线合一(1条高速公路线、1条城市主干道线及1条双线铁路线)公铁两用悬索桥主桥跨径为(52+800+800+52)m,加劲梁采用钢箱-桁架组合形式,其断面形式新颖,为研究该桥颤振稳定性能,确保桥梁的抗风安全,对主桁架梁节段进行1∶46.3的缩尺模型风洞试验,并探讨了风嘴以及栏杆位置、高度、透风率等各种气动措施对颤振临界风速的影响。结果表明:该桥在-3°攻角下,颤振临界风速小于相应的颤振检验风速,存在发生颤振的可能性;增设风嘴能提高负攻角下的颤振临界风速,但正攻角下颤振临界风速会有所降低;合理地改变上、下游栏杆位置、高度、透风率等组合措施,能使桥梁在各攻角情况下的颤振临界风速满足要求。

The span arrangement of the main bridge of a three-line （1 expressway line, 1 city trunk road line and 1 double-track railway line） rail-cure-road suspension bridge is （52＋800＋800 ＋52） m. The stiffening girder of the bridge is designed as the combined steel box and truss gird- er and structurally, the cross section of the girder is quite novel. To study the flutter stability and to ensure the wind resistant safety of the bridge, the wind tunnel test of the scaled-down model of 1 ： 46.3 for the sections of the main truss girder was conducted and the influences of the various aerodynamic measures including the wind fairings and the positions, height and ventila- tion rates of the balustrades on the flutter critical wind speeds were studied. The results of the test and study demonstrate that for the bridge at the -3° wind attack angle, the flutter critical wind speed is less than the corresponding flutter checking wind speed and the possibility of the flutter occurrence exists. The installing of the wind fairings on the bridge can increase the flutter critical wind speeds at the negative wind attack angles, but at the positive wind attack angles, the critical wind speeds may decrease. The reasonable changing of the measures of the positions, height and ventilation rates of the balustrades on the upstream and downstream sides of the bridge can make the flutter critical wind speeds of the bridge at the different wind attack angles meet the requirements.