Evaluation of site effects in some localities of ‘Alta Val Tiberina Umbra’ (Italy) by numerical analysis

Pergalani, F.; Compagnoni, Marco Antônio; Petrini, V.

doi:10.1016/s0267-7261(02)00169-0

Cited by 9 publications

(6 citation statements)

References 3 publications

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“…This approach is in line with those that have been applied for microzonation studies, especially in Central Italy, since the 1997-1998 Umbria-Marche seismic sequence (Marcellini and Maugeri, 2001a, b;Pergalani et al, 2003;Mucciarelli and Tiberi, 2004).…”

Section: Introductionsupporting

confidence: 81%

“…According to various authors recently involved in seismic microzonation activities in Italy (Tento et al, 2001;Pergalani et al, 2003), F a may be determined as the ratio of the SI calculated at the site to the SI calculated at the bedrock (corresponding in this case to the reference station -R). Therefore, the F a value in each station (Table III) was derived from the average of the SI (station) /SI (reference station) ratios calculated for each event of Table II.…”

Section: Remarks On Seismic Amplification In Fault Zonesmentioning

confidence: 99%

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Evidence of Amplification Effects in Fault Zone Related to Rock Mass Jointing

et al. 2006

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Results of geological, geomechanical and seismometric investigations aiming at the analysis of the seismic response in a carbonate ridge of the Nera River valley (Central Apennines -Italy) are discussed. Geological and geomechanical surveys were aimed at defining the stratigraphic and structural setting of the outcropping formations and the jointing conditions of the rock mass. Velocimetric records of both ambient noise and small-magnitude earthquakes were analysed in order to identify amplification conditions. The analysis was carried out in the time domain, through directional energy evaluation, and in the frequency domain, through H/V spectral ratios and spectral ratios with respect to a reference station. A local amplification factor was estimated from Housner intensity. The study revealed a significant seismic amplification in a fault zone. This effect was observed in intensely jointed and mylonitic rock masses, located inside moderately jointed rock masses, and is the result of specific geometries and significant impedance contrasts. A map of fault zones prone to amplification of ground motion was constructed, taking into account the jointing conditions of the rock masses and the structural setting of the investigated ridge. The study relied on an integrated methodological approach, which combined the available data under union and intersection criteria.

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Section: Introductionsupporting

confidence: 81%

Section: Remarks On Seismic Amplification In Fault Zonesmentioning

confidence: 99%

Evidence of Amplification Effects in Fault Zone Related to Rock Mass Jointing

et al. 2006

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“…The effect of soil nonlinearity on 2D valley effects has been extensively examined in the literature with various methods ranging from equivalent linear to fully inelastic analysis (Marsh et al, 1995;Zhang and Papageorgiou, 1996;Pavlenko, 2001;Pergalani et al, 2003;Olsen et al, 2006;Lenti et al, 2009;Gelagoti et al, 2010). Most studies conclude that soil inelasticity reduces 2D valley amplification, and hence AG tends to diminish.…”

Section: The Effect Of Soil Nonlinearitymentioning

confidence: 99%

Nonlinear Dimensional Analysis of Trapezoidal Valleys Subjected to Vertically Propagating SV Waves

Gelagoti

Kourkoulis

Anastasopoulos

et al. 2012

Bulletin of the Seismological Society of America

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This paper studies the seismic response of soil basins emphasizing the sensitivity of 2D dynamic response to geometric and material properties. This is accomplished through a formal dimensional analysis accounting for fully inelastic soil response thus augmenting the generalization potential of the results, and providing a novel framework for future research on the subject. It is shown that 2D valley response may be described through the following key dimensionless parameters:(1) the valley shape factor s, expressing the slope inclination; (2) the impedance ratio i, which expresses the stiffness of the soil relative to the bedrock; (3) the wavelength ratio λ S , which is a function of soil stiffness and seismic excitation frequency; (4) the rigidity ratio v, expressing the stiffness of the soil relative to its strength; and (5) the resistance ratio r, which expresses the degree of soil nonlinearity. The effectiveness of the dimensional formulation is verified through the numerical analysis of equivalent valleys, assuming elastic and nonlinear soil response. Finally, a parametric study is conducted to gain insight on the effects of the introduced dimensionless parameters on the dynamic response of trapezoidal alleys. It is shown that decreasing the valley slope or the wavelength ratio promotes wave reflections within the wedge, thus enhancing the possibility of wave interferences and subsequently leading to 2D aggravation on the valley surface. On the other hand, the geometry-dependent parasitic vertical acceleration increases as the valley slope becomes steeper. As the degree of soil nonlinearity increases, 2D phenomena tend to become localized close to the valley edges.

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“…We examine the predictive power of V S,30 , F 0 (as derived from synthetic amplification functions), and I w . The amplification factor, F a , is used here to define the seismic amplification of a site as proposed by Pergalani et al (1999) and Pergalani et al (2003):…”

Section: Prediction Of Ground Motion Amplificationmentioning

confidence: 99%

“…Thus, F a estimates the average amplification due to the soil properties with respect to rock. F a is an appropriate parameter to evaluate site effects since the spectrum inten- sity SI (Equation 2) relates better to the building damage (the word "damage" is used here to indicate the physical damage of a building and not a measure of structural response) than other ground motion parameters such as PGA, PGV, and S a ͑f͒ (e.g., Pergalani et al 1999, Miyakoshi and Hayashi 2000, Pergalani et al 2003. Indeed, the spectrum intensity accounts for the amplitude and frequency content (in the range of importance for structures) of earthquakes in a single parameter (Kramer 1996, Miyakoshi andHayashi 2000).…”

Section: Psv͑t͒dt ͑2͒mentioning

confidence: 99%

Assessing the Effectiveness of Soil Parameters for Ground Response Characterization and Soil Classification

et al. 2008

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The average shear wave velocity over the top 30 m of a soil profile ( VS,30) represents an usual parameter for soil classification in a modern building code for seismic design. In this work the ground response of about 100 soil profiles in Tuscany and Molise (Italy) is studied through 1-D numerical simulations in order to evaluate the reliability of European and Italian soil classifications based on the VS,30 criterion. The amplification factor, Fa, defined here as the ratio of the pseudo-velocity response spectrum intensity (Housner 1952) at the surface, S Is, to the pseudo-velocity response spectrum intensity at the rock outcrop, S Ir, is related to some soil parameters, such as VS,30, the fundamental frequency of vibration of the soil column, F0, and seismic impedance contrast, Iw. Analyzing the standard deviation of the residual obtained from regression analyses of Fa versus VS,30, F0, and Iw shows that F0 is the most helpful parameter for the prediction of Fa. Hence F0 appears to be more appropriate than VS,30 and Iw for the characterization of the seismic response of a site and, therefore, should not be disregarded in building code soil classifications.

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Evaluation of site effects in some localities of ‘Alta Val Tiberina Umbra’ (Italy) by numerical analysis

Cited by 9 publications

References 3 publications

Evidence of Amplification Effects in Fault Zone Related to Rock Mass Jointing

Evidence of Amplification Effects in Fault Zone Related to Rock Mass Jointing

Nonlinear Dimensional Analysis of Trapezoidal Valleys Subjected to Vertically Propagating SV Waves

Assessing the Effectiveness of Soil Parameters for Ground Response Characterization and Soil Classification

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