Aerodynamic Nonlinearities of Coupled Soft Flutter of a Flat Closed-box Bridge Section

被引：0
|
作者：
Gao G.-Z. [1 ,2 ]
Zhu L.-D. [2 ,3 ,4 ]
Wu H. [5 ]
Li J.-W. [1 ]
机构：
[1] School of Highway, Chang'an University, Xi'an, 710064, Shaanxi
[2] School of Civil Engineering, Tongji University, Shanghai
[3] State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai
[4] Key Laboratory of Transport Industry of Bridge Wind Resistance Technology, Tongji University, Shanghai
[5] China Resources Land Co., Ltd., Shanghai
来源：
Zhongguo Gonglu Xuebao/China Journal of Highway and Transport | 2019年 / 32卷 / 10期
关键词：
Bridge engineering; Limit cycle oscillation; Nonlinear self-excited vibration; Soft flutter; Spring-suspended sectional model test;
D O I：
10.19721/j.cnki.1001-7372.2019.10.012
中图分类号：
学科分类号：
摘要：
To study the nonlinear characteristics of soft flutter of long-span bridges, spring-suspended sectional model tests were conducted to investigate the soft flutter behaviors of a typical flat closed-box girder bridge deck with a width-to-depth ratio of 10.7. A novel, high-precision aerodynamic-force measurement technique was adopted. This technique enabled synchronous measurement of the aerodynamic force and displacement with interiorly installing force balances to reduce the component of inertial force acting on force balances and hence increase the measurement precision of the self-excited force. Experimental results indicated that a flat closed-box section underwent soft flutter under attack angles of 5°, ±3°, and 0°. The observed soft flutter exhibited limit cycle oscillations (LCOs) with a continuous increase of amplitude along with wind velocity; with the increase of attack angle, the onset wind speed of soft flutter and the slope of the amplitude versus wind speed curve both decreased. Soft flutter occurred in the torsional mode; some higher order harmonic components were present in the heaving and torsional displacement spectrum, but these were very slight and thus ignorable when compared with the fundamental component. An obvious heave-torsion coupling effect was observed in the soft flutter of the investigated flat closed-box bridge section and the coupling increased with increasing wind speed. During post-flutter LCOs, the sectional model was found to vibrate in a quasilinear complex torsional mode. With increasing amplitude, the modulus of the complex torsional mode was reduced by 15% but the phase changed very little (by <3%). Based on the technique of synchronous measurement of aerodynamic force and displacement with interiorly installing force balances, the measured nonlinear self-excited force signals were found to accurately predict coupled soft flutter responses. The measured self-excited lift and torque were found to contain significant higher order harmonic components. © 2019, Editorial Department of China Journal of Highway and Transport. All right reserved.
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页码：125 / 134
页数：9
相关论文
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