1,721,024 research outputs found
Reliable ground displacements from analogic recordings
No full textThe aim of this paper is to try to carry out, from analog records obtained in the acquisition of strong Italian earthquakes, a correct processing and interpretation of strong ground motions, with the goal of implementing, databases and databank. A methodology is proposed, to process reliable and important analog records in such a way to obtain physical displacements. © 2015, International Society for Structural Health Monitoring of Intelligent Infrastructure, ISHMII. All rights reserved
Protection of a monumental building against traffic-induced vibrations
No full textTo preserve an ancient building in Rome against traffic-induced vibrations, an anti-vibration system was introduced under the paving of the near Lungotevere road. An experimental investigation was recently carried out by ENEA in order to analyze the traffic-induced vibrations in the basement of the building and the effectiveness of the intervention. Wave propagation in the soil around the building in presence of the anti-vibration paving was compared with that in absence of the anti-vibration paving. The study showed the importance of the taking into account the contribution of other structures in the area to the dynamic behaviour of the whole system
Seismic input characterization for some sites in Italy
No full textThe seismic input characterization is the first task in the analysis of the seismic behaviour of a structure. The definition of the seismogenetic sources, earthquake catalogue and site characteristics are preliminary to the study. The seismic input may be represented by means of a response spectrum or time-histories. There are many methodologies to produce response spectra and/or input time histories for a given site. The approach may be probabilistic, strictly deterministic or a mixture of both. A strictly deterministic approach is based on the identification of the maximum credible earthquake within an accepted return period. This can be achieved by taking into account both the seismicity historically observed at the site and the features of the seismic sources able to affect the site. The probabilistic hazard assessment is based on Cornell's methodology; it requires the definition of homogeneous seismic sources, their characterization in terms of maximum expected magnitude and Gutenberg-Richter relation (recurrence of events in different magnitude classes) and the choice of an attenuation law for seismic energy, according to the selected ground motion parameter. The methodology proposed by ENEA perform all tasks of the deterministic approach but requires also the comparison between the Fourier amplitudes of the selected time histories with the Uniform Hazard Spectrum (UHS) recovered from the probabilistic approach by means of a statistical index indicating the best fitting. Two case studies are show
Design of temporary and permanent arrays to assess dynamics parameters in historical and monumental buildings
No full textIn this paper some issues about the seismic monitoring of historical and monumental buildings are faced. The experimental analysis carried out on a earthquake damaged building is shown. On the basis of the experimental results obtained by means of temporary arrays, a permanent network was designed and installed, which recorded several seismic events. © 2005 Springer
Interpretation of records from temporary and permanent instrumentation to identify the dynamic response of a historical building to seismic actions
No full textThe CEDRAV building in Cerreto di Spoleto, originally a monastery, was built in the 14th century on the top of a rock ridge. The two events occurred on September 26th, 1997, with magnitude Ms=5.4 and Ms=6, respectively, caused damages to it. Ambient vibration measurements were first performed by using fifteen SS-1 uniaxial velocity sensors (natural frequency 1.0 Hz) connected to five K-2 recorders and deployed in nine different configurations. Then the building was permanently instrumented by using 36 accelerometers. Results from analyses of representative seismic response data acquired from the building specific permanent deployment are also included and classified by means of cumulative normalized energy plots. The building is very complex and rigid. In fact, translational and torsional frequencies are close to one another, coupling occurs and damping ratio is low. Coupling of the frequencies and low damping are two factors that cause beating effect when shaking is strong enough. In the case of this study, the shaking levels are not large but yet the building is affected by beating effect. As stated the CEDRAV is an old buildings and has been altered repeatedly over time. This will cause dynamic interactions with other buildings or sub-structures during an earthquake.. On the base of recorded data a preliminary analysis in frequency domain, based on the determination of auto and cross power spectral density, has been carried out. Then the modal structure's identification has been performed by means of Ibrahim technique, working in the time domain, and Frequency Domain Decomposition technique, working in the frequency domain
- …
