紊流风场中桥梁气动导数识别的随机方法  

STOCHASTIC SYSTEM METHOD FOR IDENTIFICATION OF AERODYNAMIC DERIVATIVES OF BRIDGE DECKS IN TURBULENT FLOW

作　　者：秦仙蓉[1] 顾明[1] 

机构地区：[1]同济大学土木工程防灾国家重点实验室

出　　处：《土木工程学报》2005年第4期73-77,共5页China Civil Engineering Journal

基　　金：国家创新研究群体基金 (50321003);国家自然科学基金(50308022);高等学校骨干教师资助计划联合资助

摘　　要：气动导数是大跨桥梁结构颤振和抖振分析的重要依据。本文提出采用随机系统识别方法来识别紊流风场中的气动导数, 与当前应用较广的瞬态激励法及强迫激励法相比, 这类方法的优势在于: (1) 将紊流看作是激励, 而不是噪声, 更能反映结构实际工作状态下的特性; (2) 识别精度不受风速的制约, 可以获得较高折减风速下的气动导数; (3) 可直接在紊流风场中结构随机响应上进行识别, 无需任何人为外在激励, 试验更为简单易行。在风洞中完成了紊流风场中桥梁节段模型测振试验, 进一步利用本文的方法识别出气动导数。与相关文献提供的类似模型在均匀场和紊流场中识别结果的对比表明: 本文识别的气动导数是可靠的, 所提出的采用随机系统识别方法来识别紊流风场中气动导数的思路是可行的。Flutter derivatives are the basis for critical wind speed prediction in the flutter analysis of bridges, and are often estimated through wind tunnel tests by system identification techniques. In this paper, stochastic system identification techniques are proposed to determine the flutter derivatives in turbulent flow. The advantages of such techniques are: (1) The turbulent flow is regarded as the input excitation, rather than noise,thus the results would reflect the in-operation characteristics of the model; (2) Precisions are not influenced by wind speed; (3) No special actuators are required, thus the relevant wind tunnel tests are quite simple. The theoretical formulation of the stochastic subspace identification technique is proposed, and wind tunnel tests are conducted and the flutter derivatives determined. The resultant flutter derivatives are consistent with those reported in the relevant literature, which proves that determining flutter derivatives in turbulent flow by stochastic system identification techniques is feasible, and the proposed method is effective.

关 键 词：气动导数 模态参数识别 随机子空间方法 风致振动 桥梁结构 

分 类 号：O329.1[理学—一般力学与力学基础] TU311.3[理学—力学]