Structure, soil–structure response and effects of damage based on observations of horizontal-to-vertical spectral ratios of microtremors

Gallipoli, Maria Rosaria; Mucciarelli, Marco; Castro, Raúl R.; Monachesi, G.; Contri, P.

doi:10.1016/j.soildyn.2003.11.009

Cited by 99 publications

(70 citation statements)

References 16 publications

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“…Firstly, it can be used with data on the buildings' fundamental frequencies to assess the possible occurrence of soil-structure resonance (e.g. Gallipoli et al, 2004;Gosar, 2012). Secondly, it can be a complement to the average S-wave velocity in the upper 30 m (V s,30 ) as proposed by Ansal (2004) and Luzi et al (2011).…”

Section: Discussionmentioning

confidence: 99%

“…Ansal, 2004;Luzi et al, 2011). The use of microtremors was later extended to study the dynamic parameters of buildings, for instance to identify their fundamental frequencies Gallipoli et al, 2004;Boutin and Hans, 2008;Gosar et al, 2010).…”

Section: Methodsmentioning

confidence: 99%

“…Among other geophysical and geotechnical methods used for level 3 microzonation, the seismological microtremor horizontal-to-vertical spectral ratio (HVSR) method has achieved high recognition in the last decade because it provides very important data on the main resonance frequency of soft sediments overlaying stiff geological bedrock (Bard, 1999). The results of the freefield microtremor measurements are thus used in different soil classification standards and are especially valuable when compared with additional microtremor measurements inside buildings to assess the danger of soil-structure resonance, which can significantly enhance the damage during earthquakes (Gallipoli et al, 2004). They are also used to constrain the S-wave velocity-depth profiles obtained from the microtremor array or MASW measurements through a joint modeling of HVSR and dispersion curves.…”

Section: Introductionmentioning

confidence: 99%

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Study on the applicability of the microtremor HVSR method to support seismic microzonation in the town of Idrija (W Slovenia)

Gosar

2017

Nat. Hazards Earth Syst. Sci.

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Abstract. The town of Idrija is located in an area with an increased seismic hazard in W Slovenia and is partly built on alluvial sediments or artificial mining and smelting deposits which can amplify seismic ground motion. There is a need to prepare a comprehensive seismic microzonation in the near future to support seismic hazard and risk assessment. To study the applicability of the microtremor horizontal-tovertical spectral ratio (HVSR) method for this purpose, 70 free-field microtremor measurements were performed in a town area of 0.8 km 2 with 50-200 m spacing between the points. The HVSR analysis has shown that it is possible to derive the sediments' resonance frequency at 48 points. With the remaining one third of the measurements, nearly flat HVSR curves were obtained, indicating a small or negligible impedance contrast with the seismological bedrock. The isofrequency (a range of 2.5-19.5 Hz) and the HVSR peak amplitude (a range of 3-6, with a few larger values) maps were prepared using the natural neighbor interpolation algorithm and compared with the geological map and the map of artificial deposits. Surprisingly no clear correlation was found between the distribution of resonance frequencies or peak amplitudes and the known extent of the supposed "soft" sediments or deposits. This can be explained by relatively well-compacted and rather stiff deposits and the complex geometry of sedimentary bodies. However, at several individual locations it was possible to correlate the shape and amplitude of the HVSR curve with the known geological structure and prominent site effects were established in different places. In given conditions (very limited free space and a high level of noise) it would be difficult to perform an active seismic refraction or MASW measurements to investigate the S-wave velocity profiles and the thickness of sediments in detail, which would be representative enough for microzonation purposes. The importance of the microtremor method is therefore even greater, because it enables a direct estimation of the resonance frequency without knowing the internal structure and physical properties of the shallow subsurface. The results of this study can be directly used in analyses of the possible occurrence of soil-structure resonance of individual buildings, including important cultural heritage mining and other structures protected by UNESCO. Another application of the derived free-field isofrequency map is to support soil classification according to the recent trends in building codes and to calibrate V s profiles obtained from the microtremor array or geophysical measurements.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Study on the applicability of the microtremor HVSR method to support seismic microzonation in the town of Idrija (W Slovenia)

Gosar

2017

Nat. Hazards Earth Syst. Sci.

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“…Measurements were performed using a time-window length variable from 6 to 10 min and a sampling frequency equal to 256 Hz. To estimate the building's fundamental period the horizontal to vertical spectral ratio (HVSR) technique has been used (Castro et al, 1998;Gallipoli et al, 2004;Di Giulio et al, 2005). Then, it was possible to estimate the building's fundamental period with a very good reliability.…”

Section: Data Analysis and Structural Dynamic Characterizationmentioning

confidence: 99%

Evaluation and considerations about fundamental periods of damaged reinforced concrete buildings

Ditommaso

Vona

Gallipoli

et al. 2013

Nat. Hazards Earth Syst. Sci.

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The aim of this paper is an empirical estimation of the fundamental period of reinforced concrete buildings and its variation due to structural and non-structural damage. The 2009, L’Aquila earthquake has highlighted the mismatch between experimental data and code provisions value not only for undamaged buildings but also for the damaged ones. The April 6th, 2009 L’Aquila earthquake provided the first opportunity in Italy to estimate the fundamental period of reinforced concrete (RC) buildings after a strong seismic sequence. 68 buildings with different characteristics, such as age, height and damage level, have been investigated by performing ambient vibration measurements which provided their fundamental translational period. Four different damage levels were considered according with the definitions by EMS 98 (European Macroseismic Scale), trying to regroup the estimated fundamental periods versus building heights according to damage. The fundamental period of RC buildings estimated for low damage level, is equal to previous relationship obtained in Italy and Europe for undamaged buildings, well below code provisions. When damage levels get higher, the fundamental periods increase, but again with values much lower than those provided by codes. Finally, the authors suggest a possible update of the code formula for the simplified estimation of the fundamental period of vibration for RC existing buildings, taking into account also the inelastic behaviour

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“…Wong et al, 1975) and experimental point of view. Due to the intrinsic difficulties in separating the building-radiated field from the incoming motion during an earthquake, alternative sources have been used: impulsive sources (Kanamori et al, 1991), ambient noise Gallipoli M.R. et al, 2004;Cornou C. et al, 2004), or snap-back test on both models (Guéguen.…”

Section: Introductionmentioning

confidence: 99%

Monitoring the response and the back-radiated energy of a building subjected to ambient vibration and impulsive action: the Falkenhof Tower (Potsdam, Germany)

Ditommaso

Parolai

Mucciarelli

et al. 2009

Bull Earthquake Eng

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The response of the soil-structure system near the Falkenhof Tower, Potsdam, Germany, has been monitored during the controlled explosion of a bomb dating to World War II. We installed eight 3-component velocimetric stations within the building and three in the surrounding area. We recorded several hours of seismic noise before and after the explosion, allowing the dynamic characterization of the structure both with ambient noise and forced vibration. We then compared the frequencies values and modal shapes of the structural modes evaluated both by analysing in the frequency domain the transfer functions and in the time-domain the different signals.Moreover, we carried out an interferometric analysis of the recorded signals in order to study the structural behaviour and to characterize the soil-structure interaction.Furthermore, we used normalized Short Time Fourier Transform (STFT) for the continuous monitoring of the structural response, in order to highlight possible frequency variations of the structural mode of vibration, and therefore of the structure's behaviour.To assess structural frequencies and to compare them with those evaluated by transfer functions, we used azimuth-dependent Fourier spectra. We also verified the suitability of the Horizontal-to-Vertical Spectral Ratio (HVSR) for estimating the dynamic characteristics of buildings when only single station seismic noise measurements are available.Regarding the structure-soil interaction, we identified the presence of a wave field back-radiated from the structure within the low amplitude seismic noise signal. In fact, in the free-field seismic noise recording spectra, peaks at frequencies consistent with those of the first two modes of the structure were recognized.

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Structure, soil–structure response and effects of damage based on observations of horizontal-to-vertical spectral ratios of microtremors

Cited by 99 publications

References 16 publications

Study on the applicability of the microtremor HVSR method to support seismic microzonation in the town of Idrija (W Slovenia)

Study on the applicability of the microtremor HVSR method to support seismic microzonation in the town of Idrija (W Slovenia)

Evaluation and considerations about fundamental periods of damaged reinforced concrete buildings

Monitoring the response and the back-radiated energy of a building subjected to ambient vibration and impulsive action: the Falkenhof Tower (Potsdam, Germany)

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