Influential Factors of Soft Flutter Phenomenon for Typical Bridge Deck Sections

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