大跨度流线型箱梁悬索桥颤振稳定性气动优化

以主跨为1 660 m流线型箱梁悬索桥为工程依托,采用风洞试验和CFD数值模拟相结合的方法对影响大跨度悬索桥颤振稳定性的主要因素(主缆空间形式、主梁气动外形和中央稳定板高度)进行了研究,并对气动控制措施机理进行了探讨.结果表明:主缆布置形式对桥梁结构颤振临界风速的影响主要表现为主缆布置形式导致桥梁结构扭转频率的改变,从而影响桥梁结构颤振临界风速;适当增加主梁断面宽高比可有效提高桥梁结构颤振临界风速;设置合适高度的中央稳定板可有效提高带水平分离板的流线型箱梁断面颤振临界风速.中央稳定板附近产生的涡会引起主梁断面竖向气动力增加,导致主梁断面竖向运动参与程度提高,抑制了主梁断面扭转运动,从而提高了流线型箱梁断面颤振稳定性.

Aerodynamic Optimization of Flutter Stability for a Long-span Streamlined Box Girder Suspension Bridge

Taking a suspension bridge with a streamlined girder of 1 660 m span as engineering background and using the methods of wind tunnel test and numerical simulation of CFD, this paper studies three main factors affecting the flutter stability of long-span suspension bridges, namely the main cable space form, aerodynamic shape of the girder section and height of central stabilizer, and then the mechanism of aerodynamic countermeasures is discussed. The results show that the influence of main cable layout on the flutter critical wind speed of bridge structures is mainly caused by the change of the torsional frequency of bridge structure according to the layout of main cables, which affects the critical wind speed of bridge structures. Appropriately increasing the ratio of width to height of the main girder section can effectively improve the flutter critical wind speed of bridge structures. Setting an appropriate height of central stabilizer can effectively improve the flutter critical wind speed of streamlined girder section with horizontal separation plates. The major effect of vortices generated near the central stabilizer is to generate the vertical aerodynamic force of streamlined main beam, leading to the increase of vertical movement degree of the main girder section and the suppression of torsional movement degree of the main girder section. Thus, the flutter stability of the streamlined girder section is improved.