Based on curve fitting of coefficients of three component forces of the Messina Straits Bridge, and the previously proposed semi-analytical expressions of flutter derivatives of flexible structure, the change of flutt...Based on curve fitting of coefficients of three component forces of the Messina Straits Bridge, and the previously proposed semi-analytical expressions of flutter derivatives of flexible structure, the change of flutter derivatives of slender bridge cross-section with respect to its aerodynamic center, rotational speed and angle variation is studied using a parametric method. The calculated results are compared with the measured ones, and expressions of flutter derivatives of the Messina Straits Bridge are derived. The intrinsic relationships existing in flutter derivatives are validated again. It is shown that the influence of the rotational speed on flutter derivatives is not negligible. Therefore, it provides an additional semi-analytical approach for analyzing flutter derivatives of the bridge with streamlined cross-section to get its aerodynamic information.展开更多
Relationships between flutter derivatives of slender bridge are investigated based on our previously proposed semi-analytical flutter derivatives of flexible structure. The intrinsic relations are validated with test ...Relationships between flutter derivatives of slender bridge are investigated based on our previously proposed semi-analytical flutter derivatives of flexible structure. The intrinsic relations are validated with test data of flutter derivatives of two bridges. Changes in flutter derivatives with the aerodynamic center, rotation speed, and angle variation are also studied by using a parametric method. The results show correctness of the proposed expressions of flutter derivatives given by authors in Ref. [1], and indicate that certain relations exist between these derivatives. It is also shown that semi-analytical flutter derivatives are applicable to bridges with a streamlined cross-section.展开更多
Combining the computational fluid dynamics-based numerical simulation with the forced vibration technique for extraction of aerodynamic derivatives, an approach for calculating the aerodynamic derivatives and the crit...Combining the computational fluid dynamics-based numerical simulation with the forced vibration technique for extraction of aerodynamic derivatives, an approach for calculating the aerodynamic derivatives and the critical flutter wind speed for long-span bridges is presented in this paper. The RNG k-ε turbulent model is introduced to establish the governing equations, including the continuity equation and the Navier-Stokes equations, for solving the wind flow field around a two-dimensional bridge section. To illustrate the effectiveness and accuracy of the proposed approach, a simple application to the Hume Bridge in China is provided, and the numerical results show that the aerodynamic derivatives and the critical flutter wind speed obtained agree well with the wind tunnel test results.展开更多
基于节段模型弯扭耦合自由振动风洞试验,在现有的最小二乘原理的基础上引入了一种新的基于粒子群算法(Particle Swarm Optimization,PSO)和灰狼算法(Grey Wolf Optimizer,GWO)的混合算法(hybrid GWO with PSO,HGWOP)以搜索相关参数,从...基于节段模型弯扭耦合自由振动风洞试验,在现有的最小二乘原理的基础上引入了一种新的基于粒子群算法(Particle Swarm Optimization,PSO)和灰狼算法(Grey Wolf Optimizer,GWO)的混合算法(hybrid GWO with PSO,HGWOP)以搜索相关参数,从而更加准确地识别桥梁断面的颤振导数。通过对理想平板和某大桥在三种加权矩阵下基于传统迭代法和HGWOP的颤振导数识别结果进行对比分析,发现HGWOP不仅能够避免初值敏感性问题,在某一阶模态信号衰减迅速时进行准确地参数搜索,还能在相对复杂的加权矩阵下进行更加稳定和准确地识别。该文提出了一种新的颤振导数识别方法,并为更加科学且复杂的加权矩阵的应用提供了可能。展开更多
The causes of the nonlinearity of self-excited aerodynamic force of bridge are interpreted from such two aspects as amplitude and wind velocity.The concept of"generalized flutter derivative"is proposed,and i...The causes of the nonlinearity of self-excited aerodynamic force of bridge are interpreted from such two aspects as amplitude and wind velocity.The concept of"generalized flutter derivative"is proposed,and its physical meaning is illustrated.The graphs of the general-ized flutter derivatives of plate and Sutong Bridge section model are plotted.The characteristics of all generalized flutter derivatives are compared and analyzed,and their superiorities are verified.The results indicate that the physical meaning of generalized flutter derivatives are more explicit compared to the traditional ones.It is more convenient to understand the nonlinearity properties of self-excited aerodynamic force of bridge according to the generalized flutter derivatives graphs with the wind velocity as the horizontal coordinate.展开更多
Flutter derivatives are essential for flutter analysis of long-span bridges,and they are generally identified from the vibration testing data of a sectional model suspended in a wind tunnel.Making use of the forced vi...Flutter derivatives are essential for flutter analysis of long-span bridges,and they are generally identified from the vibration testing data of a sectional model suspended in a wind tunnel.Making use of the forced vibration testing data of three sectional models,namely,a thin-plate model,a nearly streamlined model,and a bluff-body model,a comparative study was made to identify the flutter derivatives of each model by using a time-domain method and a frequency-domain method.It was shown that all the flutter derivatives of the thin-plate model identified with the frequency-domain method and time-domain method,respectively,agree very well.Moreover,some of the flutter derivatives of each of the other two models identified with the two methods deviate to some extent.More precisely,the frequency-domain method usually results in smooth curves of the flutter derivatives.The formulation of time-domain method makes the identification results of flutter derivatives relatively sensitive to the signal phase lag between vibration state vector and aerodynamic forces and also prone to be disturbed by noise and nonlinearity.展开更多
文摘Based on curve fitting of coefficients of three component forces of the Messina Straits Bridge, and the previously proposed semi-analytical expressions of flutter derivatives of flexible structure, the change of flutter derivatives of slender bridge cross-section with respect to its aerodynamic center, rotational speed and angle variation is studied using a parametric method. The calculated results are compared with the measured ones, and expressions of flutter derivatives of the Messina Straits Bridge are derived. The intrinsic relationships existing in flutter derivatives are validated again. It is shown that the influence of the rotational speed on flutter derivatives is not negligible. Therefore, it provides an additional semi-analytical approach for analyzing flutter derivatives of the bridge with streamlined cross-section to get its aerodynamic information.
文摘Relationships between flutter derivatives of slender bridge are investigated based on our previously proposed semi-analytical flutter derivatives of flexible structure. The intrinsic relations are validated with test data of flutter derivatives of two bridges. Changes in flutter derivatives with the aerodynamic center, rotation speed, and angle variation are also studied by using a parametric method. The results show correctness of the proposed expressions of flutter derivatives given by authors in Ref. [1], and indicate that certain relations exist between these derivatives. It is also shown that semi-analytical flutter derivatives are applicable to bridges with a streamlined cross-section.
基金National Natural Science Foundation of China Under Grant No. 50278029
文摘Combining the computational fluid dynamics-based numerical simulation with the forced vibration technique for extraction of aerodynamic derivatives, an approach for calculating the aerodynamic derivatives and the critical flutter wind speed for long-span bridges is presented in this paper. The RNG k-ε turbulent model is introduced to establish the governing equations, including the continuity equation and the Navier-Stokes equations, for solving the wind flow field around a two-dimensional bridge section. To illustrate the effectiveness and accuracy of the proposed approach, a simple application to the Hume Bridge in China is provided, and the numerical results show that the aerodynamic derivatives and the critical flutter wind speed obtained agree well with the wind tunnel test results.
文摘基于节段模型弯扭耦合自由振动风洞试验,在现有的最小二乘原理的基础上引入了一种新的基于粒子群算法(Particle Swarm Optimization,PSO)和灰狼算法(Grey Wolf Optimizer,GWO)的混合算法(hybrid GWO with PSO,HGWOP)以搜索相关参数,从而更加准确地识别桥梁断面的颤振导数。通过对理想平板和某大桥在三种加权矩阵下基于传统迭代法和HGWOP的颤振导数识别结果进行对比分析,发现HGWOP不仅能够避免初值敏感性问题,在某一阶模态信号衰减迅速时进行准确地参数搜索,还能在相对复杂的加权矩阵下进行更加稳定和准确地识别。该文提出了一种新的颤振导数识别方法,并为更加科学且复杂的加权矩阵的应用提供了可能。
基金The research was supported by the National Natural Science Foundation of China(Grant No.50708012)co-supported by the New Faculty Research Fund for the Doctoral Program of Higher Education by the Ministry of Education of China(No.20070141073).
文摘The causes of the nonlinearity of self-excited aerodynamic force of bridge are interpreted from such two aspects as amplitude and wind velocity.The concept of"generalized flutter derivative"is proposed,and its physical meaning is illustrated.The graphs of the general-ized flutter derivatives of plate and Sutong Bridge section model are plotted.The characteristics of all generalized flutter derivatives are compared and analyzed,and their superiorities are verified.The results indicate that the physical meaning of generalized flutter derivatives are more explicit compared to the traditional ones.It is more convenient to understand the nonlinearity properties of self-excited aerodynamic force of bridge according to the generalized flutter derivatives graphs with the wind velocity as the horizontal coordinate.
文摘Flutter derivatives are essential for flutter analysis of long-span bridges,and they are generally identified from the vibration testing data of a sectional model suspended in a wind tunnel.Making use of the forced vibration testing data of three sectional models,namely,a thin-plate model,a nearly streamlined model,and a bluff-body model,a comparative study was made to identify the flutter derivatives of each model by using a time-domain method and a frequency-domain method.It was shown that all the flutter derivatives of the thin-plate model identified with the frequency-domain method and time-domain method,respectively,agree very well.Moreover,some of the flutter derivatives of each of the other two models identified with the two methods deviate to some extent.More precisely,the frequency-domain method usually results in smooth curves of the flutter derivatives.The formulation of time-domain method makes the identification results of flutter derivatives relatively sensitive to the signal phase lag between vibration state vector and aerodynamic forces and also prone to be disturbed by noise and nonlinearity.
