Research on the Influence of the Aerodynamic Measure on the Flutter Derivative of the Steel Truss Suspension Bridge

2012 ◽  
Vol 532-533 ◽  
pp. 252-256
Author(s):  
Hua Bai ◽  
Wei Guo ◽  
Wei Li ◽  
Yu Li
Keyword(s):  
Wind Velocity ◽  
Suspension Bridge ◽  
Gansu Province ◽  
Attack Angle ◽  
Segment Model ◽  
Steel Truss ◽  
Critical Wind Velocity ◽  
Flutter Derivative ◽  
Vibration Tests ◽  
Structure Setting

Flutter derivative is a significant index of the structure flutter stability. Identifying flutter derivative precisely contributes to the bridge flutter stability analyzing. In this paper, we take a research on the Liujiaxia Bridge in Gansu Province, China. Different flutter derivatives, which were got via segment model vibration tests with different aerodynamic measures, were classified, and made comparison in order to get the law of how different aerodynamic measures effect on the flutter derivative. The results show that, setting central stabilized plate, Build-in deflector, flange plate all affect flutter derivative significantly, which leads to changes in the flutter critical wind velocity of the structure. Setting central stabilized plate above the deck contributes to identify the flutter derivative of the 0° and positive attack angle, while setting central stabilized plate will contribute to flutter derivative identification at negative angles. It will make it difficult to identify the flutter derivative at 0° and -3° if the built-in deflector was set. Wind plate contributes to the identification of the flutter derivative at +3°, however, it will make it harder to identify the flutter derivative at 0° and -3°.

Research on the Aerodynamic Measures Impact on Flutter Stability of Steel Truss Suspension Bridge

2013 ◽  
Vol 791-793 ◽  
pp. 378-381
Author(s):  
Hua Bai ◽  
Sen Hua Huang
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Suspension Bridge ◽  
Wind Tunnel Experiment ◽  
Attack Angle ◽  
Torsional Stiffness ◽  
Critical Wind Speed ◽  
Guide Plate ◽  
Steel Truss ◽  
Better Than

The flutter stability of the steel truss suspension bridge is hard to reach the requirement of the wind resisting stability when lacks the torsional stiffness. This paper discusses the influence of aerodynamic measure combination, such as central stabilizer, air director enclosed anti-collision bar and so on, towards the flutter stability of steel truss through the wind tunnel experiment of the bridge of Liu Jia gorge. The result shows: the effect of using both the upper and lower stabilized plate is better than separated used it. when sectionalized dispose upper stabilized plate, the flutter critical wind speed of attack angle will decrease rapidly. Outlaying the horizontal guide plate is better than internally installed; The flutter stability of different attack angle tend to be balanced by widening the horizontal guide plate. The anti-collision bar can be functionalized as the central stabilizer by heightening and enclosing, and effectively increase the critical wind speed of different attack angles of the high truss suspension bridge.

Research on the Impact of Damping to the Flutter Derivatives of Steel Truss Suspension Bridge

2012 ◽  
Vol 532-533 ◽  
pp. 325-329
Author(s):  
Hua Bai ◽  
Cheng Fang ◽  
Yu Li
Keyword(s):  
Wind Speed ◽  
Damping Ratio ◽  
Angle Of Attack ◽  
Suspension Bridge ◽  
Gansu Province ◽  
Critical Wind Speed ◽  
Flutter Derivative ◽  
Torsional Damping ◽  
The Impact ◽  
Flutter Derivatives

The flutter derivative is the important basic tache of bridge flutter stability analysis. Taking the Liujiaxia Bridge in Gansu province as the research object, this dissertation studies the impaction of damping ratio on the flutter derivatives and the critical wind speed through different series of section model vibration test. The results showed that the change of vertical bending and torsional damping ratio have no obvious regular influence on the eight flutter derivatives. But the changing of vertical bending and torsional damping ratio have the greatly impact on the critical wind speed at 0° and -3° angle of attack. When it is at 0° angle of attack ,the vertical bending damping ratio ζh is increased by 23%,the torsional damping ratio is increased by 0.63%, the flutter critical wind speed is increased by 4%;when the ζh is increased by 1.04%, the ζα is increased by 0.87% , the flutter critical wind speed is increased by 7%. When it is at -3° angle of attack, the vertical bending damping ratio remained around 0.8%, the torsional damping ratio is increased from 0.65% to 1.05%, the flutter critical wind speed is increased by 14%; when the ζα is increased from 0.65% to 2.05%, the flutter critical wind speed is increased by 24 %.When it is at +3 °angle of attack, the vertical bending and torsion damping ratio have little effect on the flutter critical wind speed.

Ambient Vibration Tests of Suspension Bridge

1978 ◽  
Vol 104 (5) ◽  
pp. 983-999
Author(s):  
Ahmed M. Abdel-Ghaffar ◽  
George W. Housner
Keyword(s):  
Suspension Bridge ◽  
Ambient Vibration ◽  
Ambient Vibration Tests ◽  
Vibration Tests

Forced and Ambient Vibration Tests and Vibration Monitoring of Hakucho Suspension Bridge

2000 ◽  
Vol 1696 (1) ◽  
pp. 57-63 ◽  
Author(s):  
Yozo Fujino ◽  
Masato Abe ◽  
Hajime Shibuya ◽  
Masato Yanagihara ◽  
Masashi Sato ◽  
...  
Keyword(s):  
Natural Frequencies ◽  
Three Dimensional ◽  
Suspension Bridge ◽  
Element Model ◽  
Vibration Monitoring ◽  
Ambient Vibration ◽  
Mode Shapes ◽  
Ambient Vibration Tests ◽  
Bending Mode ◽  
Vibration Tests

Forced and ambient dynamic tests of the Hakucho Bridge were carried out to study the dynamic characteristics of this suspension bridge. Dense-array measurement was employed in order to capture not only natural frequencies and damping, but also the mode shapes of the bridge. The natural frequencies and mode shapes obtained from the forced and ambient vibration tests agreed well with those calculated by a three-dimensional finite element model. A new method that combines the random decrement method with the Ibrahim time domain method is proposed to systematically identify the natural frequencies, damping, and mode shapes. This method is successfully applied to ambient vibration data. It is shown that the natural frequency of the first vertical bending mode decreases noticeably as the wind speed increases. It is also shown that the shape of the first vertical bending mode changes slightly near the towers, depending on the wind velocity; this finding indicates that the change may be associated with friction in the bearings at the towers. Finally, application of the Global Positioning System to measure static displacement of the girder is explained.

On the Parametric Excitation of a Nonlinear Aeroelastic Oscillator

2002 ◽  
Author(s):  
H. Lumbantobing ◽  
T. I. Haaker
Keyword(s):  
Wind Velocity ◽  
Critical Points ◽  
Limit Cycles ◽  
Parametric Excitation ◽  
Original System ◽  
Finite Amplitude ◽  
Stability Diagrams ◽  
Averaged Equations ◽  
Critical Wind Velocity ◽  
Simple Picture

In this paper the following equation for the parametric excitation of a nonlinear aeroelastic oscillator of seesaw type is considered: θ¨+1−εa0cos(ωt)θ=εF(θ,θ˙,μ). In this equation εF represents the aeroelastic force, μ the wind velocity and ε denotes a small parameter. To study the dynamics of the oscillator we use the method of averaging. In absence of parametric excitation one typically finds that above a critical wind velocity the oscillators rest position becomes unstable and stable oscillations with finite amplitude result. Addition of the parametric excitation changes this simple picture. On changing the wind velocity local bifurcations like pitchfork, saddle-node and Hopf bifurcations lead to new nontrivial critical points and limit cycles in the averaged equations. In addition, a global saddle-connection bifurcation is found which either creates or destroys a limit cycle. Note that critical points and limit cycles in the averaged system correspond to periodic solutions and periodically modulated solutions of the original system. An analysis for the possible stability diagrams of the trivial solution and the location of bifurcations in the parameter space is presented. Finally, the numerical calculations performed match with the obtained analytical results and provide phaseportraits for some especial cases.

Comparison of wind characteristics at different heights of deep-cut canyon based on field measurement

2019 ◽  
Vol 23 (2) ◽  
pp. 219-233 ◽  
Author(s):  
Jingyu Zhang ◽  
Mingjin Zhang ◽  
Yongle Li ◽  
Chen Fang
Keyword(s):  
Wind Speed ◽  
Vertical Direction ◽  
Suspension Bridge ◽  
Longitudinal Direction ◽  
Longitudinal Component ◽  
Attack Angle ◽  
Gust Factor ◽  
Long Span ◽  
Wind Characteristic ◽  
Wind Characteristics

The typical U-shaped deep-cut canyon is widely distributed in the western mountainous areas of China, especially in Sichuan province and Yunnan province. The deep-cut canyon has the characteristics of the high drop in elevation, high-temperature difference, and complex wind environment. A 50 m high meteorological mast with a total of eight anemometers was erected in such topography, and a long-span suspension bridge will be constructed in the area where the meteorological mast is located. Based on the long-term monitor data, the wind characteristic parameters including average and fluctuating wind characteristics and coherence between different heights are investigated. The results are as follows. The dominant wind direction which depends on the topography is north–south. The attack angle of wind is mainly less than zero, and its probability distribution obeys the hypothetical Gaussian distribution. Both the increases in height of anemometer and in wind speed reduce the dispersion of the attack angle of wind. The gust factor has a similar change law of attack angle of wind. Turbulence intensities are affected by the height of the anemometer and the wind speed, and they are different from the recommended value of China Codes. In terms of turbulence integral length scale, the value increases with an increase in the height of the anemometer in the same component. The largest value occurs in the longitudinal direction and the smallest occurs in the vertical direction at the same level. The coherence between any two locations is relatively strong, and the longitudinal component is stronger than others. The measured wind power spectrum for longitudinal, lateral, and vertical wind in deep-cut canyon fits the von Kármán model better.

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