Seismic-Wave Propagation in Alluvial Basins and Influence of Site-City Interaction

Semblat, Jean‐François; Kham, Marc; Bard, Pierre Yves

doi:10.1785/0120080093

Cited by 67 publications

(55 citation statements)

References 30 publications

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“…Despite different physical origins, the observations made in the resonant X-direction (double-peak resonance, antiresonance trough, modified phase) recall those described in dynamics when two co-resonant mass-spring systems are associated (Hartog 1956). Numerical simulations, reported by Wirgin & Bard (1996), Clouteau & Aubry (2001), Semblat et al (2008) and Groby & Wirgin (2008) have shown similar splits of the layer resonance when adding resonant structures at the top surface of an elastic layer. However, comparisons are not straightforward due to different sets of configurations, hypotheses and frequency ranges in the models.…”

Section: Site-city Interactionsupporting

confidence: 53%

Site-city interaction: theoretical, numerical and experimental crossed-analysis

Schwan¹,

Boutin

Padrón

et al. 2016

Geophys. J. Int.

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S U M M A R YThe collective excitation of city structures by a seismic wavefield and the subsequent multiple Structure-Soil-Structure Interactions (SSSIs) between the buildings are usually disregarded in conventional seismology and earthquake engineering practice. The objective here is to qualify and quantify these complex multiple SSSIs through the design of an elementary study case, which serves as a benchmark for theoretical, numerical and experimental crossed-analysis. The experimental specimen consists of an idealized site-city setup with up to 37 anisotropic resonant structures arranged at the top surface of an elastic layer and in co-resonance with it. The experimental data from shaking table measurements is compared with the theoretical and numerical results provided respectively by an equivalent city-impedance model derived analytically from homogenization in the long-wavelength approximation and a model based on boundary elements. The signatures of the site-city interactions are identified in the frequency, time and space domain, and in particular consist of a frequency-dependent free/rigid switch in the surface condition at the city resonance, beatings in the records and the depolarization of the wavefield. A parametric study on the city density shows that multiple SSSIs among the city structures (five are sufficient) can have significant effects on both the seismic response of its implantation site and that of the buildings. Key parameters are provided to assess site-city interactions in the low seismic frequency range: They involve the mass and rigidity of the city compared to those of the soil and the damping of the building.Key words: Earthquake dynamics; Earthquake ground motions; Body waves; Seismic anisotropy; Site effects; Wave propagation. I N T RO D U C T I O NUrban and industrial areas require a particular attention in seismic analysis due to the concentrations of population, real estates, strategic public services and human activities having a large socioeconomical impact. However, the presence of the city is usually disregarded in conventional methods applied in seismology and earthquake engineering: The ground motion is supposed to result from the seismic source and substratum properties only, for example, Bonnefoy-Claudet et al. (2008), while the response of a structure to the ground motion is studied independently from the surrounding buildings, for example, Jennings & Bielak (1973). These standard approaches omit the effects of multiple soil-structures dynamic interactions on the seismic field and the buildings' response.While these approximations are reasonable in most cases, they are questionable in urban areas, where high-rise buildings, similar in height and design, are built closely from one another. Neighbouring buildings can exchange significant amounts of energy with each other, and form, with the soil, a fully coupled dynamic system that should be treated as a whole. The problem of mutual interactions between two buildings have been formulated initially by Luco & Contesse (19...

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Section: Site-city Interactionsupporting

confidence: 53%

Site-city interaction: theoretical, numerical and experimental crossed-analysis

Schwan¹,

Boutin

Padrón

et al. 2016

Geophys. J. Int.

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“…This result is consistent with the findings of Mucciarelli et al (2008) andDitommaso et al (2009), who noticed that, although the soil-structure interaction in inhabitated areas might act in general as a dampener for the recorded wavefield (Semblat et al, 2008), there is a shift of energy that concentrates at frequencies close to the frequencies of the buildings yielding to local peaks of amplification in the Fourier spectrum.…”

Section: Building-soil Interactionsupporting

confidence: 92%

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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“…The inertial soil-structure interaction effect on the freefield ground motion is also known for a long time (Jennings 1970;Kanamori et al 1991). However, the site-city interaction effects, which significantly modify the free-field ground motion in basins, became a critical issue only after the 1985 Mexico earthquake (Wirgin and Bard 1996;Guéguen et al 2002;Kham et al 2006;Semblat et al 2008). Very large reduction of spectral amplification at double resonance (37.10 %) at the top of B8 building in regular homogeneous city 2 at its natural frequency (1.15 Hz) as compared to the single B8 building in the same basin was obtained.…”

Section: Discussionmentioning

confidence: 99%

“…In SCI, both the kinematic and inertial interactions play their roles, but it is very difficult to separate out the individual effect during an earthquake excitation. Kham et al (2006) and Semblat et al (2008) reported that the SCI under double-resonance condition can lead to a significant variation of seismic wave field as compared to the free-field motion and concluded that the effects of SCI are beneficial in some parts of the city and detrimental in the other parts of the basin. The SCI effects on the ground motion strongly depend on the urban configuration mainly on the city heterogeneity and city density.…”

mentioning

confidence: 99%

Study of role of basin shape in the site–city interaction effects on the ground motion characteristics

2014

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In this paper, the role of basin shape in the site-city interaction (SCI) effects on the ground motion characteristics is documented. The effects of city type and city density on the free-field motion are also documented. The seismic responses of various 2D basin models with different shapes as well as city type and city density were simulated using a fourth-order accurate staggered-grid viscoelastic SH-wave finite-difference algorithm. The analysis of simulated responses of various site-city models, ground motion perturbations and spectral amplifications revealed that basin shape plays an important role in SCI effects on the ground motion. Further, a considerable SCI effect was obtained at the double resonance. The city density seems to be a more prominent parameter of SCI, which largely reduces the ground motion amplitude in the city as compared to the height of buildings. It was also inferred that the existence of different types of buildings may result in a decrease in coherency of building response.

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Seismic-Wave Propagation in Alluvial Basins and Influence of Site-City Interaction

Cited by 67 publications

References 30 publications

Site-city interaction: theoretical, numerical and experimental crossed-analysis

Site-city interaction: theoretical, numerical and experimental crossed-analysis

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

Study of role of basin shape in the site–city interaction effects on the ground motion characteristics

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