基于解析模态分解法的桥梁动态应变监测数据温度影响的分离

PDF(1847 KB)

振动与冲击 ›› 2012, Vol. 31 ›› Issue (21) : 6-10.

论文

基于解析模态分解法的桥梁动态应变监测数据温度影响的分离

李苗1，任伟新1，胡异丁1,2，王宁波1

作者信息 +

Application of analytical mode decomposition method to separate temperature effectfrom dynamic strain measurements

Li Miao1, Ren Wei-xin1, Hu Yi-ding1,2, Wang Ning-bo1

Author information +

文章历史 +

摘要

对于大跨度桥梁结构，温度荷载会对结构应变产生显著影响。为得到桥梁在动荷载下的真实应变，对其运营状况做出正确评估，有必要将温度变化对应变的影响从结构应变中剔除。对比分析了悬索桥钢桁架跨中上弦杆的温度应变片和工作应变片数据的功率谱密度，得到应变片输出信号在各频段的能量分布特征，确定了工作应变片数据中温度应变信息和动荷载应变信息的分界频率；采用解析模态分解法，根据分界频率将工作片原始应变时程分离为慢变成分和快变成分两部分。结果表明，由温度变化产生的应变时程波动（慢变成分）得到有效分离，该方法不仅能去除温度变化引起的应变片自身的应变，同时温度应力引起的应变亦得到有效剔除；通过雨流计数法对提取出的快变成分进行检验分析。结果表明，快变成分较好地保留了桥梁动荷载产生的应变信息，具有较高的工程利用价值。

Abstract

Under temperature load, structure stress of long-span bridge changed and strain of structure was affected remarkably. For proper assessment of bridge operation condition, it’s highly necessary to remove the effect of varying temperature on strain data and get the structure strain induced by dynamic load on bridge. Dynamic strains of the active strain gauges fixed on chord of steel truss at mid span of suspension bridge and inactive strain gauges, that didn’t sense mechanical surface strains but temperature variation induced strains, were analyzed. According to normalized PSD (power spectral density) ratio, the information in strain data of the active gauges were separated into two parts in frequency domain which were respectively dominated by varying temperature and dynamic load using the value of dividing frequency. After nalytial mode decomposition method being applied to the strain data, the slow-varying component and fast-varying component are obtained. The fact that fast-varying component did not fluctuate periodically showed the slow-varying component including strain of gauges and stress-induce strain of structure under temperature variation is effectively eliminated from strain data of the active strain gauges. Through test analysis with rain-flow counting method, strain amplitude information of fast-varying component and original data from active gauges are similar. It’s concluded that fast-varying component properly retained the information of dynamic load produced strain and is of some practical engineering value.

导出引用

李苗;任伟新;胡异丁;王宁波. 基于解析模态分解法的桥梁动态应变监测数据温度影响的分离[J]. 振动与冲击, 2012, 31(21): 6-10

Li Miao;Ren Wei-xin;Hu Yi-ding;Wang Ning-bo. Application of analytical mode decomposition method to separate temperature effectfrom dynamic strain measurements[J]. Journal of Vibration and Shock, 2012, 31(21): 6-10