【摘要】 将特征正交分解型谱表示法运用于模拟具有桥塔风效应的桥梁风场中。首先介绍桥塔风效应和桥梁风场的概率描述,然后结合模态截断技术,介绍特征正交分解(Proper Orthogonal Decomposition,POD)型谱表示法,该方法是对常用的原型谱表示法的继承和提高,且物理概念更加清晰。通过引入对风速谱矩阵的显式预分解,推导模拟具有桥塔风效应的桥梁风场的简化计算公式,将对付目标功率谱矩阵的特征值分解运算简化为对实矩阵的运算。该方法可用FFT加速,相对于原有的模拟方法具有较高的计算效率。最后,以模拟龙潭河特大桥施工最大双悬臂阶段的脉动风速场为算例,解释了脉动风速过程特征正交分解模态的物理意义,说明该方法的可靠性。在算例中,观察到复杂相关结构下,特征正交分解发生振型交换的现象,并分析其原因。更多还原

【Abstract】 The proper orthogonal decomposition(POD)-based spectral representation method is used to digitally simulate wind fields around bridges with wind passage effects.Firstly,stochastic models of wind field and wind passage effects are described.Combined with the modal truncation technique,formulas of the simulation method are derived,the new method can be explained in physical perpective more clearly than using the original spectral representation method.By introducing a pre-decomposition of the prescribed spectral matrix of the wind field,a simplified formula for the simulation is obtained.Consequently,only the decomposition computation for eigenvectors of a real power spectral matrix rather than a complex one is needed,so that higher computation efficiency of the method may be obtained due to elimination of the time-consuming Cholesky decomposition procedure as well as using FFT technique and the modal truncation technique.A numerical example is used to illustrate this method,to verify it,and to demonstrate that the method is potential for applications in civil engineering.In the example,the phenomenon that the POD modes of the bridge wind field change their forms with increasing frequency is observed and studied.更多还原