大跨斜拉桥自由振动阻尼识别与不确定性分析  

Damping Identification and Uncertainty Analysis of Long-Span Cable-Stayed Bridges Based on Free Vibration

作　　者：封周权[1,2] 石双发 张吉仁 贺耀北 王甜 华旭刚[1,2] FENG Zhouquan;SHI Shuangfa;ZHANG Jiren;HE Yaobei;WANG Tian;HUA Xugang(Hunan Provincial Key Laboratory of Wind and Bridge Engineering,College of Civil Engineering,Hunan University,Changsha 410082,China;State Key Laboratory of Bridge Safety and Resilience,Hunan University,Changsha 410082,China;Hunan Provincial Communications,Planning,Survey&Design Institute,Changsha,410200,China)

机构地区：[1]湖南大学风工程与桥梁工程湖南省重点实验室,湖南长沙410082 [2]桥梁工程安全与韧性全国重点实验室,湖南大学,湖南长沙410082 [3]湖南省交通规划勘察设计院有限公司,湖南长沙410200

出　　处：《应用基础与工程科学学报》2025年第1期12-23,共12页Journal of Basic Science and Engineering

基　　金：国家自然科学基金项目(52178284,51708203);智慧城市物联网国家重点实验室(澳门大学)开放课题(SKL-IoTSC(UM)-2021-2023/ORP/GA09/2022);重庆市自然科学基金项目(CSTB2022NSCQ-MSX1465);湖南省研究生科研创新项目(CX20230443)。

摘　　要：结构阻尼比对桥梁抗风设计和减振控制至关重要.对数衰减法作为一种经典的阻尼比识别方法,尽管应用广泛,但受噪声等因素影响,衰减周期数的选择会显著影响阻尼比的识别精度.为了提升对数衰减法在工程中的适用性,首先建立了对数衰减法的不确定性分析理论模型,推导出最优衰减周期数的理论计算式以及恒定的最优振幅比.其次,通过单自由度数值算例验证了所提方法的有效性和鲁棒性.最后,将解析模态分解法与所提方法相结合,并将其应用于某大跨度钢混组合梁斜拉桥的阻尼比识别.研究结果表明,最优衰减周期数对应于最大振幅衰减至0.3299倍时,阻尼比识别的不确定性最小.由于振幅依赖性影响,识别所得大跨度钢混组合梁斜拉桥的阻尼比结果相对离散,但均约为1%,与公路桥梁抗风规范推荐值接近.该研究成果为对数衰减法的工程应用提供了借鉴.Structural damping ratios are crucial for the wind resistance design and vibration control of bridges.The logarithmic decrement method,a classic approach for damping ratio identification,is widely used;however,its accuracy can be significantly affected by noise and the choice of decay periods.To enhance the applicability of the logarithmic decrement method in engineering practice,this paper first establishes a theoretical model for uncertainty quantification of the method,deriving theoretical formulas for the optimal number of decay periods and a constant optimal amplitude ratio.Next,the effectiveness and robustness of the proposed method are verified through a single-degree-of-freedom numerical example.Finally,the method is combined with the analytical mode decomposition method and applied to identify the damping ratio of a long-span steel-concrete composite girder cable-stayed bridge.The results indicate that the optimal number of decay periods corresponds to the point where the maximum amplitude decays to 0.3299 times its original value,minimizing the uncertainty in damping ratio identification.Due to amplitude dependency,the identified damping ratios for the long-span steel-concrete composite girder cable-stayed bridge are relatively dispersed but generally around 1%,aligning closely with the recommended values in wind-resistant design specification for highway bridges.The findings of this study provide valuable guidance for the engineering application of the logarithmic decrement method.

关 键 词：大跨斜拉桥 阻尼识别 对数衰减法 自由振动 不确定性量化 信号分解 

分 类 号：U441.3[建筑科学—桥梁与隧道工程]