苏通大桥结构健康状态评估技术研究与应用(2):主梁损伤预警

为了建立"环境因素归一化"的苏通大桥主梁损伤预警方法,本文对苏通大桥主梁240天的小波包能量谱与温度实测数据进行了季节相关性研究。分析结果表明,苏通大桥主梁的小波包能量谱与温度具有明显的季节相关性,其特征频带能量比的日平均值,随着温度的季节变化在一年中可以发生平均约200%的变化。在此基础上,采用6次多项式模型对小波包能量谱—温度进行了统计建模,并采用均值控制图法对特征频带能量比的异常变化进行了统计模式识别。结果表明,运用本文方法可以有效地消除温度的季节变化对斜拉桥实测小波包能量谱的影响,较好地识别出结构损伤引起的特征频带能量比10%的异常变化,适合于苏通大桥主梁的实时在线监测。

Technology and Application of Structural Health Condition Assessment for Sutong Bridge(2):Damage Alarming of Main Girder

In order to establish an environmental-condition-normalized damage alarming method for main girder of Sutong Bridge,the seasonal correlation analysis of wavelet packet energy spectrum(WPES) and temperature of Sutong Cable-stayed Bridge is performed by means of the 240-day health monitoring data.The analysis results reveal that the measured WPES has remarkable seasonal correlation with the environmental temperature.The seasonal change of environmental temperature accounts for the variation of the damage alarming parameter Ip of the dominant frequency bands with an averaged variance of 200%.The statistical modeling technique using a 6th-order polynomial is adopted to formulate the correlation between the WPES and temperature,on the basis of which the abnormal changes of measured damage alarming parameter Ip are detected using the mean value control chart.It is found that the proposed method can effectively eliminate temperature complications from the time series of WPES and exhibit good capability for detecting the damage-induced 10% variances of the damage alarming parameter Ip.And the proposed WPES-based method is proved to be suitable for online real-time condition monitoring for main girder of Sutong Bridge.