刚度、阻尼矩阵非对称性对气动导数识别的影响

针对桥梁结构节段模型风洞测振试验中因风的作用而导致的系统刚度矩阵和阻尼矩阵的非对称性可能影响识别结果这一问题,利用状态空间法仿真薄平板模型在均匀风场中的自由衰减响应和紊流场中的抖振响应,分别采用特征实现算法(ERA)和随机子空间法(SSI),识别出均匀流场和紊流风场中的理想薄平板模型气动导数.通过与仿真所用的薄平板模型的气动导数理论值的对比,确定等效刚度矩阵和等效阻尼矩阵的非对称性对系统识别方法所得结果的影响.仿真结果表明,目前,应用比较广泛的ERA方法和SSI方法,均对阻尼矩阵和刚度矩阵的非对称性具有足够的适应性.

Effects of Asymmetrical Equivalent Stiffness and Damping Matrices on Flutter Derivatives of Bridge Decks

Effects of the asymmetry of equivalent stiffness and damping matrices on the identification of flutter derivatives of bridge deck are investigated by a series numerical simulation.The state-space method is employed to numerically simulate the wind-induced buffeting responses of a thin flat plate.The flutter derivatives of the thin flat plate model are extracted from the simulated free-decayed response and buffeting response by two popular modal parameter identification algorithms,the eigensystem realization algorithm(ERA) and the covariance-driven stochastic subspace identification(SSI),respectively.The identified results are then compared with the theoretical values of a thin flat plate given by Theodorson.The comparison suggests that effects of the unsymmetrical stiffness and damping matrices on the identification of flutter derivatives are not remarkable,and both of the methods of ERA and SSI are suitable for identification of flutter derivatives of bridge decks.