Continuous monitoring of high-rise buildings using seismic interferometry

TitleContinuous monitoring of high-rise buildings using seismic interferometry
Publication TypeJournal Article
Year of PublicationSubmitted
AuthorsMordret, A, Sun, H, Prieto, GA, M. Toksöz, N, Büyüköztürk, O
JournalBulletin of the Seismological Society of America
Abstract

The linear seismic response of a building is commonly extracted from ambient vibration mea3

surements. Seismic deconvolution interferometry performed on ambient vibrations can be used

4 to estimate the dynamic characteristics of a building, such as the shear-wave velocity and the

5 damping. The continuous nature of the ambient vibrations allows us to measure these parame6

ters repeatedly and to observe their temporal variations. We used 2 weeks of ambient vibration

7 recorded by 36 accelerometers installed in the Green Building at theMIT campus to monitor the

8 shear-wave speed and the apparent attenuation factor of the building. Due to the low strain of

9 the ambient vibrations, we observe small speed changes followed by recoveries. We show that

10 measuring the velocity variations for the deconvolution functions filtered around the fundamen11

tal mode frequency is equivalent to measuring the wandering of the fundamental frequency in

the raw ambient vibration data. By comparing these results with local weather parameters, we

13 show that the air humidity is the factor dominating the velocity variations in the Green Building,

14 as well as the wandering of the fundamental mode. The one-day periodic variations are affected

15 by both the temperature and the humidity. The apparent attenuation, measured as the expo16

nential decay of the fundamental mode waveforms, is strongly biased by the amplitude of the

17 raw vibrations and shows a more complex behavior with respect to the weather measurements.

18 We have also detected normal mode non-linear interaction for the Green Building probably

19 due to heterogeneity or anisotropy of its structure. We found that the temporal behavior of the

20 frequency singlets may be used for monitoring.

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