scholarly journals Diagrams to Find the Critical Wind Velocity for Quay Mooring

1993 ◽  
Vol 88 (0) ◽  
pp. 85-93
Author(s):  
Motoaki HANABUSA ◽  
Kinzo INOUE ◽  
Norio MIZUMA ◽  
Toshihiko ANRAKU
Keyword(s):  
Wind Velocity ◽  
Critical Wind Velocity

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.

On Aerodynamic Stability of Membrane Structures

2005 ◽  
Vol 20 (3) ◽  
pp. 181-188 ◽  
Author(s):  
Qing-Shan Yang ◽  
Rui-Xia Liu
Keyword(s):  
Wind Velocity ◽  
Potential Flow ◽  
Dynamic Equilibrium ◽  
Three Dimensional ◽  
Flow Theory ◽  
Membrane Structures ◽  
Moment Theory ◽  
Shallow Shells ◽  
Potential Flow Theory ◽  
Critical Wind Velocity

The aerodynamic instability critical wind velocity of three-dimensional membrane structures is studied by combining the non-moment theory of thin shallow shells and the potential flow theory in fluids. The dynamic equilibrium equation of the structure is established by applying the non-moment theory of thin shells, with the assumption that the coming flow is uniform ideal potential flow. The aerodynamic interaction equations of the membrane structure in two cases, i.e., the wind is in the structural arch or sag direction, are obtained based on the aerodynamic forces being determined by applying the potential flow theory and the thin airfoils theory in which the wind-structure interaction is taken into account. Bubnov-Galerkin approximate method is applied to transform the interaction equation into a second order linear ordinary differential equation; and the instability critical wind velocity is obtained from Routh-Hurwitz stability criterion.

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°.

Study on Galloping Critical Wind Velocity of High-Rise Structure

ICLEM 2010 ◽  
2010 ◽  
Author(s):  
Xuezhi Wang ◽  
Jinkun Dong ◽  
Pin Zhang ◽  
Yunfen Feng
Keyword(s):  
Wind Velocity ◽  
High Rise ◽  
Critical Wind Velocity

scholarly journals Damping flutter oscillation of suspension bridges

1986 ◽  
Vol 8 (3) ◽  
pp. 19-25
Author(s):  
Nguyen Van Tinh
Keyword(s):  
Numerical Calculation ◽  
Wind Velocity ◽  
Structural Parameters ◽  
Suspension Bridges ◽  
Critical Wind Velocity ◽  
Tacoma Narrows Bridge

The paper deals with flutter problem of suspension bridges in regard to damping. The formulated expression makes possible to obtain the dependence of critical wind velocity and other structural parameters. Numerical calculation, is given of the Tacoma Narrows Bridge and for some values of parameters.

Sign in / Sign up

Export Citation Format

Share Document