Abstract

This study addresses the quantification and compensation of the so-called mass loading effect, a disturbance that typically occurs in structural health monitoring of bridges. Source of this effect is the time-variant traffic, which means that dynamic performance indicators such as identified resonance frequencies are also time-variant. Basis of this study is the ambient acceleration response of a freeway bridge in the Alps recorded in a long-term monitoring campaign. After statistical evaluation of the traffic over the bridge, stochastic finite element simulations are performed to quantify the effect of time-variant truck traffic on a resonance frequency identified from the recorded accelerations, which serves as performance indicator. The corresponding natural frequency of the numerical bridge-truck model is obtained both by modal analyses and response history analyses, whose results however show considerable differences. In an effort to reduce the temporal scatter of the performance indicator, the corresponding natural frequency of the numerical model is used to compensate for the mass loading effect. It it shown that the mass loading effect plays a significant role for the considered bridge, although temperature effects dominate as a disturbance for the identified resonance frequency.

摘要

本研究解决了所谓的质量载荷效应的量化和补偿问题，这种干扰通常发生在桥梁的结构健康监测中。这种影响的来源是时变流量，这意味着动态性能指标（如识别出的共振频率）也是时变的。这项研究的基础是在长期监测活动中记录的阿尔卑斯山高速公路桥梁的环境加速度响应。在对桥上的交通进行统计评估后，执行随机有限元模拟以量化随时间变化的卡车交通对从记录的加速度中识别出的共振频率的影响，该共振频率用作性能指标。数值桥车模型的相应固有频率是通过模态分析和响应历史分析获得的，但其结果显示出相当大的差异。为了减少性能指标的时间分散，数值模型的相应固有频率用于补偿质量加载效应。它表明，质量负载效应对所考虑的桥梁起着重要作用，尽管温度效应作为已识别共振频率的干扰占主导地位。