Procedura automatica per lo studio dei segnali registrati da una stazione tiltmetrica

La Tiltmetria costituisce un metodo di misura in continuo della deformazione del suolo attraverso il monitoraggio delle variazioni di inclinazione nel tempo sia in ampiezza che in direzione ed è particolarmente utilizzata nelle aree vulcaniche e sismogenetiche attive [Wyatt et al., 1988; Ricco et al., 1991; Ricco et al., 2000; Ricco et al., 2003; Ricco et al., 2007]. La rete tiltmetrica gestita dalla Sezione Osservatorio Vesuviano dell’ INGV è composta da 7 stazioni in registrazione continua ai Campi Flegrei, 5 delle quali (DMA, DMB, DMC, BAI ed OLB) sono equipaggiate con sensori di superficie e 2 (OLB e TOI) anche con sensori borehole; al Vesuvio invece esistono 2 stazioni con sensori di superficie (OVO e CMD) (fig. 1) [Aquino et al., 2006]

Ground tilt monitoring at Phlegraean Fields (Italy): a methodological approach

Among geodetic methods used for monitoring ground deformation in volcanic areas, tiltmetry represents the most rapid technique and therefore it is used by almost all the volcanological observatories in the world. The deformation of volcanic building is not only the result of endogenous causes (i.e. dykes injection or magma rising), but also non-tectonic environmental factors. Such troubles cannot be removed completely but they can be reduce. This article outlines the main source of errors affecting the signals recorded by Phlegraean tilt, network, such as the dependence of the tilt response on temperature and to the thermoelastic effect on ground deformation. The analytical procedure used to evaluate about such errors and their reduction is explained. An application to data acquired from the tilt network during two distinct phases of ground uplift and subsidence of the Phlegraean Fields is reported

Monitoraggio geodetico dell’area vulcanica napoletana: risultati della livellazione geometrica di precisione eseguita ai Campi Flegrei a settembre 2008

Lo studio ed ilmonitoraggio deimovimenti verticali del suolo ai Campi Flegrei (Italy) sono effettuati con continuità da oltre 30 anni, operando su linee di livellazioni preesistenti istituite e/o ampliate da vari Enti a partire dal 1905 (IGM, Genio Civile e lo stesso INGV- NA Oss. Vesuviano). Attraverso i dati rilevati dal 1970 ad oggi sono state acquisite molte informazioni sulla deformazione del suolo durante le varie fasi di bradisismo discendente e ascendente ed attualmente si dispone di un importante data-base che può essere integrato con i risultati ottenuti dalle altre metodologie geodetiche. In questa nota presentiamo i risultati della campagna di livellazione geometrica di precisione eseguita su alcuni tratti della rete altimetrica dei Campi Flegrei nel Settembre 2008. Dopo la fase di lento sollevamento, iniziata nel 2004 e culminata alla fine del 2006 con un valore massimo di 55 mm rilevato a Pozzuoli (Lungomare Pertini) al caposaldo n. 23, nell’area flegrea è ripresa una fase di lenta subsidenza caratterizzata da una evidente decelerazione durante il 2008 rispetto all’anno precedente. Per delineare meglio e dettagliare l’attuale fase del bradisismo flegreo, si è ritenuto utile effettuare il confronto tra i dati altimetrici acquisiti nelle ultime 3 campagne (2006, 2007 e 2008) da cui è emersa una evidente disomogeneità del campo di spostamento verticale osservato

A study of tilt change recorded from July to October 2006 at the Phlegraean Fields (Naples, Italy)

The tiltmetric dataset of Phlegraean Fields area showed a discrete correlation with the volcanic dynamics, suggesting that tiltmetric monitoring is important for the surveillance of active volcanic areas. Tilt data recorded in 2006 at 2 stations belonging to the monitoring network of the Osservatorio Vesuviano (INGV, National Institute for Geophysics and Volcanology, Italy) in the Phlegraean Fields are discussed in this paper. The acquired signals have shown a strong tiltmetric inversion that took place from the end of July 2006. After correcting tilt variations to eliminate the influence of temperature (influencing 90% of the signal at OLB station, hereafter OLB) a significant value of the tilt still remains. This change is related to a local inflation episode lasting 3 months, during an unrest phase that started 2 years before. It is interesting to note that tilt amplitude is much greater at OLB than the slope of the displacement field predicted by the theoretical inflation models, but data show that this field is not homogeneous and in some areas very tilted. Moreover, in the last days before the end of tilt inversion, a low energy seismic swarm happened at about 1 km of distance from the tiltmetric station by hundreds of VT (Volcano-Tectonics) and LP (Long-Period) events

A component-level methodology to evaluate the seismic repair costs of infills and services for Italian RC buildings

The reliable estimation of seismic losses due to damage to buildings is paramount for the post-emergency management and the planning of recovery activities. For residential reinforced concrete (RC) infilled buildings, a significant role in the computation of seismic loss is played by non-structural components, above all infills, partitions and services, as shown in past earthquakes. In this work, a component-based methodology is proposed to assess seismic losses for residential RC buildings in Mediterranean region. The attention is focused on the repairing activities for masonry infills (typical enclosure or partitions elements in Italian and Mediterranean RC buildings), and for services (plumbing systems, electric equipment, floor/wall tiles…), commonly enclosed within the infill panels for the considered building typology. The described methodology can be used starting from the expected damage level to infills and partitions. It adopts given repair unit costs at different damage states of infills. The loss estimation methodology has been, first, validated by comparing predicted and actual repair costs for specific case-study buildings damaged by L’Aquila (Italy) 2009 earthquake. Then, the methodology has been applied to a wide dataset of RC buildings (about 2500 residential buildings) damaged by L’Aquila earthquake available from the literature, to show its possible application at a large-scale level. A good agreement between observed and predicted costs is obtained both for specific case-study buildings and for the wider building stock, especially when damage to structural components is very limited

INTEGRATED ANALYSIS OF GROUND DISPLACEMENT DATA, SEISMIC ACTIVITY AND MORPHOMETRIC DATA OF THE CAMPI FLEGREI (CAMPANIA, SOUTHERN ITALY) 2000-2006 RECENT BRADYSEISMIC CRISES, IN GIS ENVIRONMENT.

In this paper the results of an integrated analysis of ground displacement data, local seismic activity and DEM image analysis, in GIS environment, which has been performed for the Campi Flegrei volcanic area, are presented and discussed. The study has been carried out for the recent bradyseismic crises of 2000-2006, with the aim of working out a preliminary interpretation of the recent dynamics of the area

E-Defense 2015 ten-story building: beam–column joint assessment according to different code-based design

Recent devastating earthquakes worldwide pointed out the importance of seismic detailing and their influence on the observed damage and subsequent repairability of reinforced concrete buildings. Several studies and post-earthquake observations remarked the role of beam–column joints (BCJs) on the global building response and the effectiveness of transverse reinforcement in increasing the joint shear strength and the ultimate deformation. Although number of experimental and theoretical studies focused on the seismic response of BCJs, their mechanical behaviour is still a discussed topic. This resulted in number of design approaches available in worldwide code or standards that lead to different quantity of joint stirrups. This study focuses on the response of BCJs of a 10-story prototype building designed according to Japanese standards and tested in 2015 on the E-Defense shaking table. First the damage assessment at global (building) and local (joint) level is performed at increasing intensities and considering the building in the base slip and base fixed configurations. A refined numerical model is then developed and validated against global and local experimental results. Then, the joint stirrups are re-designed according to different international standards (ACI, EC8, NZS) and different numerical models are developed. The numerical results are then compared in terms of interstorey drift demand and joint shear strain. Finally, a comparison in terms of expected damage varying the design approach of joint stirrups is proposed

Seismic Loss Estimation in Pre-1970 Residential RC Buildings: The Role of Infills and Services in Low–Mid-Rise Case Studies

The lessons learned after recent earthquakes have highlighted the key role played by infills and services in damage and loss of Reinforced Concrete (RC) buildings. Their influence in seismic performance and loss estimation of selected RC building case studies is thoroughly analyzed here. The case study selection aims to be representative of existing buildings built in Italy before 1970, and covers a different number of stories and design typologies. The seismic responses of the case-study buildings are numerically analyzed by means of non-linear static pushover analysis (PO) considering a lumped plasticity approach with a quadri-linear flexural response for beam/column elements (properly calibrated for RC elements reinforced with plain bars) and a tri-linear compressive-only axial response with diagonal concentric struts for infill panels (empirically derived from experimental data on hollow clay masonry walls). Economic loss estimation is carried out via a component-based methodology that relies on the main repairing activities and resultant costs required for the refurbishment of infills and services for different damage levels. Accordingly, a damage analysis is performed herein, given the intensity measure, based on a comparison between Interstory drift demand from PO analysis and drift-based fragility functions specific for masonry infills. Loss curves, relating the total building repair cost to peak ground acceleration (PGA), are presented and compared for the analyzed case study buildings to show their trends and quantify the incidence of infills and services with respect to the reconstruction cost. A comparison between these outcomes and those recently found in the literature emphasizes the robustness of the considered approach and the reliability of the hypotheses about damage and loss assessment

A study of tilt change recorded from July to October 2006 at the Phlegraean Fields (Naples, Italy)

The tiltmetric dataset of Phlegraean Fields area showed a discrete correlation with the volcanic dynamics, suggesting that tiltmetric monitoring is important for the surveillance of active volcanic areas. Tilt data recorded in 2006 at 2 stations belonging to the monitoring network of the Osservatorio Vesuviano (INGV, National Institute for Geophysics and Volcanology, Italy) in the Phlegraean Fields are discussed in this paper. The acquired signals have shown a strong tiltmetric inversion that took place from the end of July 2006. After correcting tilt variations to eliminate the influence of temperature (influencing 90% of the signal at OLB station, hereafter OLB) a significant value of the tilt still remains. This change is related to a local inflation episode lasting 3 months, during an unrest phase that started 2 years before. It is interesting to note that tilt amplitude is much greater at OLB than the slope of the displacement field predicted by the theoretical inflation models, but data show that this field is not homogeneous and in some areas very tilted. Moreover, in the last days before the end of tilt inversion, a low energy seismic swarm happened at about 1 km of distance from the tiltmetric station by hundreds of VT (Volcano-Tectonics) and LP (Long-Period) events