Citation

Guéguen P, Langlais M, Garambois S, Voisin C, Douste-Bacqué I. Bull. Earthq. Eng. 2017; 15(3): 889-906.

Copyright

(Copyright © 2017, European Association on Earthquake Engineering, Publisher Holtzbrinck Springer Nature Publishing Group)

DOI

10.1007/s10518-016-9995-3

PMID

unavailable

Abstract

In this paper, a simple analysis is done to explain the observed increase of resonance frequency of City-Hall building in Grenoble (France), a 12-story reinforced concrete building. This period corresponds also to the observed variation of the resonance frequency of the Grenoble's sedimentary basin. The postulated hypothesis is that the frequency increase reflects the stiffness increase of the soil-structure system related to the cold period that hit Western Europe in 2012. To explore this hypothesis we have processed continuous recording during the early 2012 recorded at the roof level and at a close free-field accelerometric station. The variation of site effect is monitored by the horizontal-to-vertical spectral ratio of seismic noise, and the variation of apparent and system frequencies of the building by the random decrement technique. Apparent frequency is computed by deconvolution method between roof and basement. The maximum freezing penetration is 0.75 m and the horizontal relative motion stiffness of the foundation is strongly sensitive to the modification of the upper soil layer. The results suggest a variation (<1 %) larger than twice the standard deviation of the natural wandering of resonance frequency observed at City-Hall building for normal weather conditions, and question on the development of realistic models developed for the detection of damage and for the physical interpretation of such frequency variations observed in actual buildings.

Language: en