典型桥梁断面软颤振现象及影响因素

Influential Factors of Soft Flutter Phenomenon for Typical Bridge Deck Sections

摘要:

采用弹簧悬挂节段模型测振的试验方法研究了常用的全封闭箱梁断面、中央开槽箱梁断面、半封闭箱断面和双边肋断面等4种典型桥梁断面可能出现的软颤振响应。试验结果表明：上述4种断面均可能出现不同尺度的软颤振现象，软颤振表现为弯扭自由度耦合的单频振动特征，其耦合程度不仅会随着风速的变化而变化，而且会随着断面流线性变好而增加; 流线性较差的钝体断面的软颤振风速区间往往很宽。桥面附属结构会增强软颤振响应，而改变结构阻尼对软颤振响应的影响并不明显。

关键词:典型桥梁断面，软颤振，弯扭自由度耦合，非线性自激力

Abstract:

A series of spring-suspended sectional model tests were carried out to investigate the soft flutter phenomena for four typical bridge deck sections including a flat full-closed box section, a centrally-slotted box section, a semi-closed box section and a twin-side-girder section, which are all common in bridge engineering. The test results show that soft flutter is a single frequency vibration coupled with torsional and vertical degree of freedoms (DOF) and could be observed in the wind tunnel tests of the four typical bridge deck sections under investigation. The degree of the above-mentioned torsional-vertical coupling varied with wind speed, and can be enhanced with the improvement of the streamlining of bridge deck sections. Generally, the bluffer the deck section is, the wider range of wind speed the soft flutter will cover. The adding of accessories on bridge decks will enhance the vibra-tion response of soft flutter. Whereas, changing structural damping ratios has a limited influence on the soft flutter phenomenon.

Key words:typical bridge deck section; soft flutter; torsional-vertical-DOF coupled vibration; nonlinear self-excited force