Salvermoser Johannes, Hadziioannou Céline, Stähler Simon C
Department for Earth and Environmental Sciences, Ludwig-Maximilians-University, Theresienstrasse 41, 80333 Munich, Germany.
Leibniz-Institute for Baltic Sea Research, Seestrasse 15, 18119 Rostock, Germany.
J Acoust Soc Am. 2015 Dec;138(6):3864-72. doi: 10.1121/1.4937765.
Structural damage on bridges presents a hazard to public safety and can lead to fatalities. This article contributes to the development of an alternative monitoring system for civil structures, based on passive measurements of seismic elastic waves. Cross-correlations of traffic noise recorded at geophone receiver pairs were found to be sufficiently stable for comparison and sensitive to velocity changes in the medium. As such velocity variations could be caused by damage, their detection would be valuable in structural health monitoring systems. A method, originally introduced for seismological applications and named Passive Image Interferometry, was used to quantify small velocity fluctuations in the medium and thereby observe structural changes. Evaluation of more than 2 months of continuous geophone recordings at a reinforced concrete bridge yielded velocity variations Δv/v in the range of -1.5% to +2.1%. The observed fluctuations correlate with associated temperature time series with a striking resemblance which is remarkable for two completely independent data sets. Using a linear regression approach, a relationship between temperature and velocity variations of on average 0.064% °C(-1) can be identified. This value corresponds well to other studies on concrete structures.
桥梁的结构损伤对公共安全构成威胁，并可能导致人员伤亡。本文基于对地震弹性波的被动测量，为土木结构开发一种替代监测系统做出了贡献。研究发现，在地震检波器接收对处记录的交通噪声的互相关足够稳定，可用于比较，并且对介质中的速度变化敏感。由于这种速度变化可能由损伤引起，因此在结构健康监测系统中检测它们将具有重要价值。一种最初用于地震学应用且名为被动图像干涉测量法的方法，被用于量化介质中的小速度波动，从而观测结构变化。对一座钢筋混凝土桥超过两个月的连续地震检波器记录进行评估，得到的速度变化Δv/v在-1.5%至+2.1%的范围内。观测到的波动与相关温度时间序列具有惊人的相似性，这对于两个完全独立的数据集来说是非常显著的。使用线性回归方法，可以确定温度与速度变化之间平均为0.064% °C(-1)的关系。该值与其他关于混凝土结构的研究结果吻合良好。
