Search Results (16)

The 2012 Emilia earthquake highlighted the vulnerability of fortified architecture. Based on the observed seismic behaviors, this research proposes a GIS geodatabase, designed with a proactive approach, for the prediction and prevention—at a territorial scale—of the most frequent damage mechanisms of the investigated typology. The designed geo-database allows for the identification of possible correlations between constructive features and the occurrence of damage, through statistical and geo-referenced analysis. Moreover, the designed geodatabase, by enabling the comparison of the damage level data with the seismic action of the site, through INGV (National Institute of Geophysics and Volcanology) shakemaps, allowed the definition of experimental fragility curves, for three of the most common damage mechanisms. By applying these functions to castles in the province of Parma, it was possible to define future seismic risk scenarios for the mechanisms considered, thanks to the use of the seismic hazard map. Therefore, the described methodology could be functional to identify the most urgent and high-priority interventions in order to optimize the management of economic resources. The final aim is to promote the application of the concept of minimum intervention, and more in general to preserve the architectural heritage, avoiding emergency interventions and aiming instead to apply planned conservation strategies. Full article

In 2015, hazard mitigation became a top priority on the international agenda, according to the United Nations Office for Disaster Risk Reduction. When it comes to architectural heritage, it is crucial to develop tools and site-specific response plans that can help the prompt and effective management of seismic events. The paper presents part of a research study carried out at the University of Parma, aimed at improving emergency strategies for the protection of cultural heritage damaged by earthquakes. Specifically, it analyses first aid and recovery reinforcements, with a specific focus on masonry churches affected by the 2012 quake in the Emilia Romagna region (Italy). The study highlights criticalities and good practices of a site-specific response. It shows that recovery with a sharp separation between emergency and reconstruction activities leads to wasted resources in terms of cost, material, and time. On the other hand, the most effective strategies for the conservation of architectural heritage in earthquake-prone areas have proved to be based on an integrated and shared approach, aimed at balancing safety, conservation, and economic issues. This leads to a broadening of the concept of emergency interventions and, more generally, of structural reinforcement in the field of architectural conservation. Full article

On 20 May 2012, an M_w 5.8 earthquake, followed by an M_w 5.6 event nine days later, struck the Emilia-Romagna region in northern Italy, causing substantial damage and loss of life. Post-mainshock, several water-related phenomena were observed, such as changes in the groundwater levels in wells, the expulsion of sand–water mixtures, and widespread liquefaction evidence such as sand boils and water leaks from cracks. We analyzed the Earth’s surface displacement during and after the Emilia 2012 seismic sequence using synthetic aperture radar images from the COSMO-SkyMed satellite constellation. This analysis revealed post-seismic ground subsidence between the Sant’Agostino and Mirabello villages. Specifically, the displacement time series showed a slight initial uplift followed by rapid subsidence over approximately four to five months. This widespread ground displacement pattern likely stemmed from the extensive liquefaction of saturated sandy layers at depth. This phenomenon typically induces immediate post-seismic subsidence. However, the observed asymptotic subsidence, reaching about 2.1 cm, suggested a time-dependent process related to post-liquefaction consolidation. To test this hypothesis, we analytically estimated the consolidation subsidence resulting from earthquake-induced excess pore pressure dissipation in the layered soil deposits. The simulated subsidence matched the observed data, further validating the significant role of excess pore pressure dissipation induced by earthquake loading in post-seismic ground subsidence. Full article

During an earthquake, excess pore water pressure generation in saturated silty sands causes a reduction in shear strength and even liquefaction of the soil. A comprehensive experimental program consisting of undrained cyclic simple-shear tests was undertaken to explore the key factors affecting the energy-based excess pore water pressure generation models for non-plastic silty sands. The examined influencing factors were non-plastic fines content (less than and greater than the threshold value ≅ 25%), packing density, vertical effective stress, applied cyclic stress ratio, and soil fabric. The relationship between excess pore water pressure ratio and dissipated energy per unit volume was found to be mainly dependent on the relative density and fines content of soil, whereas the cyclic stress ratio, initial vertical effective stress, and soil fabric (i.e. the reconstitution method) appeared to have a minor impact. A revision of the original energy-based model developed for clean sand by Berrill and Davis was proposed to improve prediction accuracy in terms of residual excess pore water pressures versus normalised cumulative dissipated energy. Nonlinear multivariable regression analyses were performed to develop correlations for the calibration parameters of the revised model. Lastly, these correlations were validated through additional cyclic simple-shear tests performed on different silty sands recovered at a site where liquefaction occurred after the 2012 Emilia Romagna (Italy) earthquake. Full article

The study reported in this paper concerns the temporal variation in the b-value of the Gutenberg–Richter frequency–magnitude law, applied to the earthquakes that struck Italy from 2009 to 2016 in the geographical areas of L’Aquila, the Emilia Region, and Amatrice–Norcia. Generally, the b-value varies from one region to another dependent on earthquake incidences. Higher values of this parameter are correlated to the occurrence of low-magnitude events spread over a wide geographical area. Conversely, a lower b-value may lead to the prediction of a major earthquake localized along a fault. In addition, it is observed that each seismic event has a different “occurrence time”, which is a key point in the statistical study of earthquakes. In particular, its results are absolutely different for each specific event, and may vary from years to months or even just a few hours. Hence, both short- and long-term precursor phenomena have to be examined. Accordingly, the b-value analysis has to be performed by choosing the best time windows to study the foreshock and aftershock activities. Full article

The study of deformation signals associated with seismicity in alluvial plain areas is a challenging topic that, however, is increasingly studied thanks to the great aid given by remote sensing techniques that exploit Synthetic Aperture Radar (SAR) data. This study focuses on the determination of the deformation field within the Emilia-Romagna Region (northern Italy), in the area comprising Modena, Reggio Emilia, and Parma cities. SAR data acquired along both orbits during the Sentinel-1 and Cosmo-SkyMed satellite missions were processed with the Small Baseline Subset interferometric technique from June 2012, after the serious seismic swarm of May 2012, to January 2022, just before the two earthquakes occurred in February 2022. The results, validated with Global Navigation Satellite System measurements, do not highlight displacements correlated with the seismicity but, thanks to their high spatial resolution, it was possible to discriminate areas affected by noticeable subsidence phenomena: (i) the highly industrialized areas located north of the municipalities of Reggio Emilia and Modena cities and (ii) a sector of the high-speed railway sited north of the Reggio Emilia city centre, close to the Reggio Emilia AV Mediopadana station. Here we show that, at least since 2012, the latter area is affected by subsidence which can be related to the secondary consolidation process of the fine soils loaded by the railway embankment. The piezometric level analysis also suggests that the lowering of the groundwater table could accelerate the subsidence rate, affecting the stability of infrastructures in highly populated and industrialized areas. Full article

In seismic-prone areas, ecclesiastical masonry complexes have shown very high vulnerability, as detected after the last Italian earthquakes, such as those that occurred in L’Aquila (2009), Emilia-Romagna (2012), Central Italy (2016), and Ischia (2017). Partial collapses often affect these types of aggregate buildings due to the presence of highly vulnerable elements, such as bell towers. Preliminary analyses, including straightforward and quick methods, are necessary to assess their vulnerability. This paper proposes a simplified method to analyse bell tower dynamic behaviour and the results obtained are compared with several different approaches. The first is based on the dynamics of two rigid blocks (bell tower and lower building), and the second concerns a single block (bell tower only). The proposed method can be considered as a quick procedure involving few parameters to provide a preliminary analysis before use of more complex models such as finite element models. It aims to provide a valuable tool for the initial evaluation of the stability and risk index of the structure. The double-block model considers the associations between the rocking of the bell tower and the sliding motion of the underlying building. A parametric evaluation for different friction coefficients is proposed. The results are represented as rotation time histories and compared with analysis of the single vulnerable element, i.e., the bell tower subjected to the floor spectrum. The results show that high excitation frequency and friction coefficient values make the bell tower stable, and that the simplified model provides a clear safety advantage. Full article

The preservation and definition of the correct retrofitting interventions of historic masonry buildings represents a relevant topic nowadays, especially in a country characterized by high seismicity zones. Considering the Italian Cultural Heritage, most of these buildings are constructed in ancient unreinforced masonry (URM) and showed a high level of vulnerability during the recent 2009 (L’Aquila), 2012 (Emilia Romagna) and 2016 (Centro Italia) earthquakes. In this paper, the seismic assessment of an historic masonry building damaged during 2016 Centro Italia seismic event is presented considering different types of retrofitting interventions. Starting from the results obtained by the post-earthquake survey, different finite element models have been implemented to perform linear and non-linear analyses useful to understand the seismic behaviour of the building and to define the appropriate retrofitting interventions. In particular, reinforced plaster layer and cement-based grout injections have been applied in each masonry wall of the building in order to improve their horizontal load-bearing capacity, and an additional wall made with Poroton blocks and M10 cement mortar has been built adjacent to the central stairwell. In addition, in view of the need to replace the roof seriously damaged during the seismic event, a cross-laminated roof solution characterized by a thickness equal to 14 cm (composed by seven layers, each 2 cm thick) has been proposed. The results show that the proposed retrofitting interventions have led to a significant improvement in the seismic behaviour of the building. Full article

Communities are confronted with the rapidly growing impact of disasters, due to many factors that cause an increase in the vulnerability of society combined with an increase in hazardous events such as earthquakes and floods. The possible impacts of such events are large, also in developed countries, and governments and stakeholders must adopt risk reduction strategies at different levels of management stages of the communities. This study is aimed at proposing a sound qualitative multi-hazard risk analysis methodology for the assessment of combined seismic and hydraulic risk at the regional scale, which can assist governments and stakeholders in decision making and prioritization of interventions. The method is based on the use of machine learning techniques to aggregate large datasets made of many variables different in nature each of which carries information related to specific risk components and clusterize observations. The framework is applied to the case study of the Emilia Romagna region, for which the different municipalities are grouped into four homogeneous clusters ranked in terms of relative levels of combined risk. The proposed approach proves to be robust and delivers a very useful tool for hazard management and disaster mitigation, particularly for multi-hazard modeling at the regional scale. Full article

The primary objective is to present the most representative types of damage observed in reinforced concrete (RC) structures due to earthquakes. Those damages are divided according to the ten most representative types. Examples and the main reasons that could trigger each failure mechanism are presented. The definition of these damage types is supported by post-earthquake damage reconnaissance missions in Sichuan (China) in 2008, L’Aquila (Italy) in 2009, Lorca (Spain) in 2011, Emilia-Romagna (Italy) in 2012, Gorkha (Nepal) in 2015, Muisne (Ecuador) in 2016 and Chiapas (Mexico) in 2017. An extensive discussion is presented concerning the infill walls’ seismic behaviour and their interaction with the RC structural elements. The presentation of the significant learnings and findings concerning the typical damage herein presented and discussed are compared with the common Southern European construction practice. The impact of the infill walls on the rehabilitation costs of damaged RC buildings is also studied. These costs are compared to those related to the structural damage and rehabilitation of the entire building structure to understand the impact of the infill walls. Finally, a case study is presented to study the effect of implementing simplified retrofitting strategies to prevent the soft-storey mechanism, one of the most common problems observed in past earthquake events. Full article

Near fault seismic records may contain impulsive motions in velocity-time history. The seismic records can be identified as impulsive and non-impulsive depending on the features that their waveforms have. These motions can be an indicator of directivity or fling step effect, and they may cause dangerous effects on structures; for this reason, there is increasing attention on this subject in the last years. In this study, we collect the major earthquakes in Italy, with a magnitude large or equal to $M_w$ 5.0, and identify the impulsive motions recorded by seismic stations. We correlate impulsive motions with directivity and fling step effects. We find that most earthquakes produced impulsive signals due to the directivity effect, though those at close stations to the 30 October 2016 Amatrice earthquake might be generated by the fling step effect. Starting from the analyzed impulses, we discuss on the potential influence of site effects on impulsive signals and suggest a characterization based on the main displacement directions of the impulsive horizontal displacements. Finally, we discuss on the damage of three churches in Emilia, which were subject to impulsive ground motion, underlying in a qualitative way, how the characteristics of the pulses may have had influences the structural response of the façades. Full article

Recently, a new strain rate map of Italy and the surrounding areas has been obtained by processing data acquired by the persistent scatterers (PS) of the synthetic aperture radar interferometry (InSAR) satellites—ERS and ENVISAT—between 1990 and 2012. This map clearly shows that there is a link between the strain rate and all the shallow earthquakes (less than 15 km deep) that occurred from 1990 to today, with their epicenters being placed only in high strain rate areas (e.g., Emilia plain, NW Tuscany, Central Apennines). However, the map also presents various regions with high strain rates but in which no damaging earthquakes have occurred since 1990. One of these regions is the Apennine sector, formed by Sannio and Irpinia. This area represents one of the most important seismic districts with a well-known and recorded seismicity from Roman times up to the present day. In our study, we merged historical records with new satellite techniques that allow for the precise determination of ground movements, and then derived physical dimensions, such as strain rate. In this way, we verified that in Irpinia, the occurrence of new strong shocks—forty years after one of the strongest known seismic events in the district that occurred on the 23 November 1980, measuring Mw 6.8—is still a realistic possibility. The reason for this is that, from 1990, only areas characterized by high strain rates have hosted significant earthquakes. This picture has been also confirmed by analyzing the historical catalog of events with seismic completeness for magnitude M ≥ 6 over the last four centuries. It is easy to see that strong seismic events with magnitude M ≥ 6 generally occurred at a relatively short time distance between one another, with a period of 200 years without strong earthquakes between the years 1732 and 1930. This aspect must be considered as very important from various points of view, particularly for civil protection plans, as well as civil engineering and urban planning development. Full article

Since few years ago only one typology of racks was used to store Grana cheese wheels for aging, which was designed focusing on the sole static behavior. Battened steel columns made by vertical tubes welded to horizontal angles were connected by means of wood boards supporting the wheels. In 2012, a strong earthquake occurred in Emilia Romagna (Italy) and a great number of these structures collapsed owing to the absence of checks for resistance against earthquakes. This catastrophic event plus the need to maximize the structural efficiency led to the development of a new typology of rack systems based on the use of cold-formed steel members. Owing to an extremely limited state-of-the-art on these modern cheese rack, design is carried out in agreement with the standard provisions calibrated and proposed for adjustable pallet racks, despite the non-negligible differences between these structural systems. The paper is focused on the comparison between the available seismic design approaches for cheese rack in order to highlight their main advantages and limits. In particular, among the four design approaches admitted in the European standards, the modal response spectrum analysis (MRSA) and the nonlinear time-history (NLTH) have been considered and the associated results compared in terms of maximum safety index of the members, global displacements and interstorey drifts. Research outcomes stress the differences associated with the considered approaches in terms of expected performance underlining the importance of an accurate definition of the behavior (q-) factor. Full article

Vulnerability is a big issue for small inland urban centres, which are exposed to the risk of depopulation. In the climate of the centre-northern part of Italy, and in the context of the recent concentration of a high number of earthquakes in that area, seismic vulnerability can become the determinant cause of the final abandonment of a small town. In some Italian regions, as well as in Emilia Romagna, municipalities are implementing seismic vulnerability reduction policies based on the Emergency Limit Condition, which has become a basic point of reference for ordinary land planning. This study proposes an approach to seismic vulnerability reduction based on valuation planning for implementation within the general planning framework of the Faentina Union, a group of five small towns located in the southwestern part of the Province of Ravenna, Italy. This approach consists of three main stages: knowledge—the typological, constructive, and technological descriptions of the buildings, specifically concerning their degree of vulnerability; interpretation—analysis with the aim of outlining a range of hypotheses with respect to damage in case of a prospective earthquake; and planning—the identification of the courses of action intended to meaningfully reduce the vulnerability of buildings. This stage includes a cost modelling tool aimed at defining the trade-off between the extension and the intensity of the vulnerability reduction works, given the budget. Full article

To investigate the geotechnical soil properties of Emilia Romagna Region, a large series of in situ tests, laboratory tests and geophysical tests have been performed, particularly at the damaged city of Scortichino—Bondeno. Deep site investigations have been undertaken for the site characterization of the soil also along the Burana-Scortichino levee. Borings, Piezocone tests (CPTU) and dynamic in situ tests have been performed. Among them, Multichannel Analysis of Surface Waves test (MASW) and Seismic Dilatometer Marchetti Tests (SDMT) have been also carried out, with the aim to evaluate the soil profile of shear wave velocity (V_s). Resonant Column Tests (RCT) were also performed in laboratory on reconstituted solid cylindrical specimens. The Seismic Dilatometer Marchetti Tests were performed up to a depth of 32 m. The results show a very detailed and stable shear wave profile. The shear wave profiles obtained by SDMT have been compared with other laboratory tests. A comparison between the in situ small shear strain, laboratory shear strain and shear strain obtained by empirical correlations, was also performed. Finally, using the results of SDMT tests, soil liquefaction phenomena have been analyzed with a new procedure based on SDMT, using the soil properties obtained by field and laboratory tests. Full article