矩形立柱非定常驰振三维非线性分析及气弹模型试验验证  

Three-dimensional Non-linear Analysis and Aeroelastic Model Test on Unsteady Galloping of Rectangular Column

作　　者：陈修煜 朱乐东[1,2,3] 檀忠旭 CHEN Xiu-yu;ZHU Le-dong;TAN Zhong-xu(State Key Laboratory of Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China;Department of Bridge Engineering,Tongji University,Shanghai 200092,China;Key Laboratory of Transport Industry of Bridge Wind Resistance Technology,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学土木工程防灾国家重点实验室,上海200092 [2]同济大学桥梁工程系,上海200092 [3]同济大学桥梁结构抗风技术交通运输行业重点实验室,上海200092

出　　处：《中国公路学报》2024年第3期321-329,共9页China Journal of Highway and Transport

基　　金：国家自然科学基金重点项目(51938012,51478360)。

摘　　要：类矩形断面因其本身较钝的气动外形而容易发生俗称为“软驰振”的风致自激振动。与经典驰振不同,这种振动不会无限发散,而是最终收敛于一个具有稳定振幅的极限环振动状态,表明其自激力存在显著的非线性特性。此外,随时间不断变化的振动特性体现其具有明显的非定常效应。在实际桥梁工程中一些类矩形钢立柱、钢吊杆或钢梁,都可能由于其钝体外形以及低质量、低阻尼等特性而发生非定常非线性驰振,因此有必要对其非定常非线性驰振响应进行精确预测。以宽高比为3∶2的矩形断面为对象,首先识别了二维驰振自激力非线性数学模型的参数;然后,考虑到驰振的非线性主要体现在其气动阻尼非线性效应上,而其气动刚度非线性效应较弱的特点,引入了振型分解法,提出了考虑结构振型和竖向平均风剖面影响的钝体立柱非定常驰振响应的三维非线性分析方法,开展了2种典型风剖面来流作用下的3∶2宽高比矩形断面立柱非定常非线性驰振响应的理论分析和气动弹性模型风洞试验案例研究,并通过比较试验与理论分析结果,验证了所提出的钝体立柱非定常驰振三维非线性分析方法的可行性和可靠性。Rectangular-like sections are prone to wind-induced self-excited vibration,commonly known as“soft galloping”,due to their blunt aerodynamic shapes.Unlike classical galloping,the vibration will not diverge infinitely but converge to a limit cycle oscillation with a stable amplitude,which shows significant nonlinear characteristics of its self-excited force.Moreover,the time-varying feature of galloping vibration also reveals notable unsteady characteristics.Such unsteady and nonlinear galloping may happen on steel and rectangular-like columns,hangers,and girders used in real bridge engineering due to their blunt shapes,low-mass,and low-damping characteristics.Therefore,it is necessary to accurately predict their responses of unsteady and nonlinear galloping.To this end,by taking a rectangular cross-section with a side ratio of 3∶2as the object,the parameters of a nonlinear mathematical model for the two-dimensional galloping self-excited force were first identified.Then,considering that the nonlinearity of unsteady galloping is mainly reflected in its aerodynamic damping effect,while the nonlinear effect of its aerodynamic stiffness is relatively weak,a three-dimensional nonlinear analysis method for the unsteady galloping responses of blunt columns,considering the influence of structural mode shape and vertical mean wind profile was proposed by the modal decomposition.On this basis,case studies of theoretical analysis and aeroelastic model wind tunnel tests were carried out on the nonlinear and unsteady galloping responses of a rectangular column with a side ratio of 3∶2under two typical wind profiles.The feasibility and reliability of the proposed three-dimensional nonlinear analysis method for the unsteady galloping responses of the blunt column were verified by comparing the experimental and theoretical results.

关 键 词：桥梁工程 非定常驰振 气动弹性模型试验 矩形立柱 非线性分析 

分 类 号：U441.3[建筑科学—桥梁与隧道工程]