环境条件影响下悬索桥模态频率变异性的定量评价  

Quantitative evaluation of variability in modal frequencies of a suspension bridge under environmental conditions

作　　者：邓扬[1] 丁幼亮[1] 李爱群[1] 

机构地区：[1]东南大学混凝土及预应力混凝土结构教育部重点实验室,南京210096

出　　处：《振动与冲击》2011年第8期230-236,共7页Journal of Vibration and Shock

基　　金：国家杰出青年基金资助项目(50725828);国家自然科学基金资助项目(50808041);教育部博士点基金(新教师基金)项目(200802861011);江苏省自然科学基金资助项目(BK2008312);东南大学优秀博士学位论文基金(YBJJ0923)

摘　　要：基于长期监测数据,研究了由环境温度、风、交通荷载和识别算法所引起的悬索桥模态频率识别的变异性。首先,采用多样本平均方法建立了温度-频率的季节相关性,减小了频率由识别算法导致的随机误差。其次,将模态频率归一化至某一参考温度以消除温度对频率的影响。通过分析小风速状态下温度归一化频率和加速度响应均方根的相关性,对交通荷载引起的频率变异性进行了定量评价,在此基础上采用交通荷载-频率相关性模型消除了交通荷载对频率的影响,最后定量评价了风速对模态频率的影响。分析结果表明:所提出的方法可以给出大跨桥梁结构模态频率识别的变异性的量化评价,但目前模态频率的识别方法仍需进一步改进。The measured variability in modal frequencies of a suspension bridge induced by temperature, w ind~ traffic loadings and identification algorithm was investigated, making use of long-term monitoring data. The seasonal temperature-frequency correlation was formulated using multi-sample averaging technique to reduce the random variation~ rising from the identification algorithm. Then the effect of temperature on the measured modal frequencies is eliminated by normalizing these modal frequencies to a reference temperature. The traffic-induced modal variability was thrthc~ quantitatively evaluated under weak wind conditions in the light of correlation analysis of the normalized modal frequenci~：s with the root mean square （RMS） of acceleration responses. Based on the traffic-frequency correlation model, the effect ot traffic loadings on the modal frequencies was eliminated and finally, the wind-induced modal variability was quantitativei） evaluated. The results indicate that the technique proposed can effectively give a quantitative evaluation of measured variability in modal frequencies of long-span bridges, however, the identification algorithm for modal frequencies.

关 键 词：结构健康监测 模态频率 环境影响 变异性 悬索桥 

分 类 号：U441[建筑科学—桥梁与隧道工程]