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“STRUCTURAL RESPONSE OF MASONRY
BUILDINGS IN THE HISTORIC CENTER OF
GENOA, ITALY”
S. Barani1,2, R. De Ferrari1,2, S. Cattari3, C. Eva2, S. Lagomarsino3 and A. Pieracci4
1Dipartimento di Scienze della Terra dell’Ambiente e della Vita, Università di Genova, Italy 2GEAmb S.r.l., spin-off dell’Università di Genova, Genova, Italy 3Dipartimento di Ingegneria Civile, Chimica e Ambientale, Università of Genova, Italy 4Autorità Portuale di Genova, Italy
Università di
Genova
Simplified geological map and maximum p.c.p.v. values recorded on the top floor of each
building along the horizontal component
The Experiment
Università di
Genova
Instruments
Solgeo Veloget 3D 1s
Solgeo Dimas 24
Solgeo Veloget 3D 1s
Solgeo Dimas 24
LE-3D/5s
LE MARSlite
LE-3D/5s
LE MARSlite
B1
B2 B3
Università di
Genova
Instruments were placed
close to vertical load resisting
elements (e.g., walls) with the
longitudinal axis (X axis)
parallel to the longer side of
the building
Data & Data Processing
Università di
Genova
1- Blasts (signals were recorded in time windows of 10 s)
2- Ambient noise
3- Earthquakes (only @ B3)
October 3, 2012 Piacenza earthquake
Ml = 4.5, ≈ 80 km from Genoa Blast recordings
Signals were employed to calculate:
a) HVSRs @ all sites
b) SSRs @ B3
Fourier spectra were smoothed
using the Konno and Ohmachi
(1998) function with a smoothing
coefficient of 20
Building B1
Ambient Noise Blasts
Fourier
Spectra
HVSR
Università di
Genova
Basement of B1 «Free Field»
HVSR
Building B2
Ambient Noise Blasts
Fourier
Spectra
HVSR
Università di
Genova
Building B3
Ambient Noise Blasts
Blasts - Y Blasts - X Blasts - Z
Università di
Genova
Fourier Spectra
(Lagomarsino, BEE, 2014)
Experimental Vs Analytical Floor Spectra
Experimental spectra
were calculated from the
recordings of the October
3, 2012 Piacenza
earthquake (Ml = 4.5)
Analytical floor spectra
accounts for the
contribution of the first
mode only
Università di
Genova
T1 = 0.33s
(= 3Hz) T2 = 0.13s
(= 7.7Hz)
H/V spectral ratios from noise recordings are consistent with those calculated using
blast signals, thus indicating that the eigenfrequency of vibration of a structure (as
derived from HVSRs) is insensitive to source signal (i.e., input excitation)
Although ambient noise H/V measurements represent an economical and flexible
alternative to SSRs, they could lead to misleading results in that it may not be possible
to distinguish the eigenfrequencies of the building from the resonance frequencies of
the foundation soil (unless they are known from free field measurements). Therefore,
the application of the SSR technique may be preferable in densely urbanized
environments where free field H/V measurements may be affected by the presence of
buildings
The amplitude of the peaks obtained from H/V spectral ratios differs from that
determined by using a reference station. As a consequence, H/V curves can not be
assumed as representative of the absolute amplification level
Conclusions
H/V spectral ratios and SSRs may be very useful to support the seismic assessment
of buildings, in order to calibrate both numerical models and the seismic demand to be
adopted in the evaluation of local mechanisms that involve the upper parts of the
structures
Università di
Genova