A nonlinear self-excited force model of soft flutter phenomenon for a twin-side-girder bridge section
ZHU Ledong1, 2, 3, GAO Guangzhong1, 2
1.State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China;
2. College of Civil Engineering, Tongji University, Shanghai 200092, China;
3. Key Laboratory of Wind Resistance Technology of Bridges of Ministry of Transport, Tongji University, Shanghai 200092, China
To investigate the soft flutter phenomenon, i.e., nonlinear post critical limit cycle oscil1ation (LCO) of a twin-side-girder section, a series of spring-suspended sectional model tests were carried out in this study. Experimental results show that the sectional model exhibited violent soft flutter phenomena in post flutter range. The observed soft flutter was a quasi-harmonic nonlinear torsional vibration with slight plunge-pitch coupling effect. The classical linear self-excited force model by Scanlan is not applicable to soft flutter. To model the aerodynamic nonlinearity during large-amplitude oscillation of soft flutter, a nonlinear self-excited force model was proposed by expressing the flutter derivatives of the classical Scanlan’s linear model as functions of transient amplitude. The identified results of the amplitude-dependant flutter derivatives showed that the nonlinearity is strong for the aerodynamic damping and very weak for the aerodynamic stiffness. The feasibility of the proposed model and the reliability of the identified aerodynamic parameters were verified by comparing the computed vibration response of soft flutter with the corresponding experimental one. The mechanism of soft flutter was then interpreted by the identified nonlinear relationships of the aerodynamic damping and the structural damping with respect to the transient vibrating amplitude.
朱乐东1,2,3，高广中1,2. 双边肋桥梁断面软颤振非线性自激力模型[J]. 振动与冲击, 2016, 35(21): 29-35.
ZHU Ledong1, 2, 3, GAO Guangzhong1, 2. A nonlinear self-excited force model of soft flutter phenomenon for a twin-side-girder bridge section. JOURNAL OF VIBRATION AND SHOCK, 2016, 35(21): 29-35.
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