Abstract
Flutter is one of the most serious wind-induced vibration phenomena for long-span bridges and may cause the collapse of a bridge (e.g., the Old Tacoma Bridge, 1940). The selection and optimization of flutter aerodynamic measures are difficult in wind tunnel tests. It usually takes a long time and consumes more experimental materials. This paper presents a quick assessment and design optimization method for the flutter stability of a typical flat box girder of the long-span bridges. Numerical analysis could provide a reference for wind tunnel tests and improve the efficiency of the test process. Based on the modal energy exchange in the flutter microvibration process, the global energy input and local energy input are analyzed to investigate the vibration suppression mechanism of a flat steel box girder with an upper central stabilizer. Based on the comparison between the experimental and numerical data, a quick assessment method for the optimization work is proposed. It is practical to predict the effects of flutter suppression measures by numerical analysis. Thus, a wind tunnel test procedure for flutter aerodynamic measures is proposed which could save time and experimental materials.
Highlights
As the spans of bridges have become larger, the bridge deck section of long-span bridges suffers aeroelastic phenomena of flutter and buffeting, as well as VIV or galloping, and the aerodynamic stability requirements of long-span bridges have become greater [1]
Based on the coupling effect of aerodynamic forces, Yang et al [4,5,6] established the relationship between torsional, vertical, and lateral vibration parameters and flutter derivatives and studied the flutter mechanism of two typical bridge sections: the closed box girder and two-isolated-girder sections. e flutter of these two sections is caused by negative aerodynamic damping, and the negative aerodynamic damping of the streamlined section is the result of the coupling effect of torsion and vertical motion
Concluding Remarks e selection and optimization of flutter aerodynamic measures are difficult to accomplish in wind tunnel tests; based on the angle of the energy exchanged in the microvibration process, both experimental and numerical methods are studied. e global and the local energy input characteristics from a macroscopic perspective were defined
Summary
As the spans of bridges have become larger, the bridge deck section of long-span bridges suffers aeroelastic phenomena of flutter and buffeting, as well as VIV or galloping, and the aerodynamic stability requirements of long-span bridges have become greater [1]. Based on the coupling effect of aerodynamic forces, Yang et al [4,5,6] established the relationship between torsional, vertical, and lateral vibration parameters and flutter derivatives (e.g., using the two-dimensional three-degree-of-freedom coupled flutter analysis method) and studied the flutter mechanism of two typical bridge sections: the closed box girder and two-isolated-girder sections. Shirai and Ueda [12] used a nonlinear turbulence model k-ε to identify the flutter derivatives of the slotted section and the section with the central stabilizer, and the flutter mechanism was explained by its calculated flow field morphology and unsteady wind pressure distribution. Bai et al [15] proposed an improved CFD method based on block-iterative coupling, performing 2D and 3D CFD simulations on two generic bridge deck sections to determine their aerodynamic force coefficients and flutter derivatives. The wind tunnel test method is used to study the energy input of the vibration suppression mechanism of the upper central stabilizer. e characteristics of global energy input and local energy input were investigated, which together demonstrate the mechanism from a macroscopic and microcosmic perspective. en, the numerical simulation method is used to accomplish bending-torsion coupling flutter for the box girder, and a numerical analysis of the effect of the upper central stabilizer on flutter stability was conducted, so the numerical simulation method can be applied to the subject, and the obtained result is determined to be applicable
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