Search Results (51)

Many urbanised areas of the Apennines, in Italy, have complex soil stratifications. A typical example is the outskirts of the city of L’Aquila, which is founded on highly heterogeneous soil layers and was severely affected by a strong earthquake in 2009. In such conditions, shear wave velocity profiles (V_S) obtained from in situ tests such as the Seismic Dilatometer Marchetti Test (SDMT) provide reliable analyses of the local seismic response. This article presents the mono-dimensional (1D) and two-dimensional (2D) seismic response analyses conducted to characterise the soil foundation of the hospital complex and adjacent university buildings in L’Aquila before their seismic retrofitting. This study emphasises the importance of accurate soil characterisation prior to repair interventions, especially in deposits where there are V_S inversions and in the presence of geometrically irregular and large structures. Under these conditions, estimating the motion amplitudes of the deposit’s higher modes beyond the fundamental level is essential in accurately characterising the seismic response, especially for buildings where higher structural modes play a significant role. The results show that approximating the V_S profile with simplified procedures, as proposed by the Italian Building Code of 2018 (equivalent V_S, similar to average), leads to incorrect estimates of seismic action. Full article

The study of the hypocenter distribution of seismic events related to fault structures is a crucial topic since it is linked to the geological features and to the dynamics of an investigated area. The hypocenter spatial distribution of earthquakes is used in a novel algorithmic method to clusterize earthquakes to accurately identify the strike and the dip parameters of seismogenic faults. Our algorithm works as a fast and efficient explorer in a five-dimensional space (x, y, z, τ, ϕ). It randomly selects several seismic events (pivots) and counts in all angular directions, for each pivot, how many hypocenters can be included in a prefixed volume (two dimensions larger than the third). The result is a volume that contains the maximum number of earthquakes occurring within a minimum distance from a flat area corresponding to the searched fault. With this volume is associated a hypocenter occurrence density angular diagram and a likelihood function. The likelihood function is useful to individuate the best value of the fault thickness and to test the hypothesis of fault flatness. Our algorithm was tested on simulated data and then successfully applied to the real case of the 2009 Mw6.1 L’Aquila (Central Italy) seismic sequence. Full article

Safety in workplaces is a requirement for work sustainability. Construction workers are frequently exposed to dangerous airborne substances. While previous studies examined chemical risks in other sectors, there is limited research on occupational chemical risk perception (OCRP) among construction workers. This study focuses on evaluating OCRP in construction workers and identifying its association with socio-demographic, occupational, and training variables. In L’Aquila, Italy, a sample of male construction workers involved in post-earthquake reconstruction were enrolled in this cross-sectional study. Chemical hazard perception, occupational exposure, personal protective equipment (PPE) use, and training were all covered by our questionnaire. Although the involved 117 workers appear to be aware of dust-related risks and asbestos-related diseases, 53% think that there is no asbestos at their worksite. Respiratory protection equipment was used by 36% of the respondents. OCRP was associated with refresher training (OR = 2.56; p = 0.025); perception of noise (OR = 10.03; p = 0.027); and solar radiation (OR = 26.07; p = 0.001). Although we observed an appropriate awareness of some occupational hazards, gaps between awareness, hazard perception, and protective behavior were evident. Comprehensive site inspections and improved risk communication are necessary to assess chemical hazards and enhance work sustainability. Full article

To safeguard historic centers with masonry buildings in medium-high seismic areas, the local seismic response (LSR) should be used. These portions of the urban areas are commonly characterized by complex subsurface features (i.e., underground cavities, buried anthropic structures, and archeological remains) that could be responsible for unexpected amplifications at period intervals similar to the building’s ones. In this study, San Giustino’s Square (Chieti, Italy) was considered due to the differentiated damage caused by the 2009 L’Aquila earthquake mainshock (6 April 2009 at 3:32 CEST, 6.3 M_w). Out of the eight buildings overlooking the square, the structure that suffered the heaviest damage was the Justice Palace. Two-dimensional finite element analyses have been carried out in San Giustino’s square to predict the LSR induced by the seismic shear wave propagation. The influence of the Chieti hill, the anthropogenic shallow soil deposit, and the manmade cavity were investigated. The results outlined that the amplifications of the seismic shaking peaked between 0.2 and 0.4 s. The crest showed amplifications over a wide period range of 0.1–0.8 s with an amplification factor (FA) equal to 2. Throughout the square, FA = 2.0–2.4 was predicted due to the cavities and the filled soil thickness. The large amplified period range is considered responsible for the Justice Court damage. Full article

The high seismic vulnerability of unreinforced masonry buildings urgently calls for researchers to develop sustainable reinforcing methods and materials. This paper presents an innovative lime-based mortar reinforced with randomly oriented basalt fibers for the reinforcement of masonry heritage. The main aim of this study is to understand the effect of the content and the length of basalt fibers on the mortar’s mechanical behavior. As a cementitious material made mostly out of lime, the mortar is chemically compatible with the historical substrate and therefore suitable in cases of restoration works on architectural heritage. Moreover, the chopped basalt fibers are randomly oriented, and this characteristic makes the overall layer effective in all directions, as the state of stress induced by seismic action is directionally undetermined. The newly proposed reinforcement system is characterized by a twofold aspect related to sustainability: 30% of the aggregates composing the mortar mix design is a recycled result of the ruins of the 2009 L’Aquila earthquake, and the chopped fibers are made out of basalt, widely known for its environmentally supportable peculiarity. The study consists of testing samples characterized by two fiber lengths and six fiber contents, along with one set of plain mortar samples. Specimens measuring 160 mm × 40 mm × 40 mm are first tested in a three-point bending (TPB) configuration, aiming to determine the flexural strength and the post-peak capacity through the calculation of the fracture energy. Then, the two broken pieces resulting from the TPB tests, each measuring 80 mm × 40 mm × 40 mm, are tested in splitting and compression, respectively, aiming to compute the tensile and compressive strengths. Finally, to provide a trend for the mortar’s mechanical properties, a regression analysis is performed by fitting the experimental data with simple linear, polynomial, and exponential regression models. Results show that: (i) both fiber content and fiber length are responsible for a linear increase of the flexural strength and the fracture energy; (ii) for both short- and long-fiber mortar samples, the tensile strength and the compressive strength parabolically increase with the fiber content; (iii) the increase in fiber content and fiber length always generates a reduction in the conglomerate workability. The fiber content (FC) optimization with respect to the mechanical properties leads to a basalt FC equal to 1.2% for long-fiber samples and an FC equal to 1.9% for short-fiber ones. Full article

This study presents the results of an experimental investigation conducted on a 2:3 scale model of a two-story stone masonry building. We tested the model on the UniKORE L.E.D.A. lab shake table, simulating the Mw 6.3 earthquake ground motion that struck L’Aquila, Italy, on 6 April 2009, with progressively increasing peak acceleration levels. We installed a network of accelerometric sensors on the model to capture its structural behaviour under seismic excitation. Medium-to lower-cost MEMS accelerometers (classes A and B) were compared with traditional piezoelectric sensors commonly used in Structural Health Monitoring (SHM). The experiment assessed the structural performance and damage progression of masonry buildings subjected to realistic earthquake inputs. Additionally, the collected data provided valuable insights into the effectiveness of different sensor types and configurations in detecting key vibrational and failure patterns. All the sensors were able to accurately measure the dynamic response during seismic excitation. However, not all of them were suitable for Operational Modal Analysis (OMA) in noisy environments, where their self-noise represents a crucial factor. This suggests that the self-noise of MEMS accelerometers must be less than 1 µg/√Hz, or preferably below 0.5 µg/√Hz, to obtain good results from the OMA. Therefore, we recommend ultra-low-noise sensors for detecting differences in the structural behaviour before and after seismic events. Our findings provide valuable insights into the seismic vulnerability of masonry structures and the effectiveness of sensors in detecting damage. The management of buildings in earthquake-prone areas can benefit from these specifications. Full article

Studies on the individuation of surface and buried faults in seismic areas using geochemical methods can be considered a valid approach for improving sustainability in the risk assessment framework. Appropriate scientific knowledge of structural geology and its evolution pre/during/post seismic events can play a fundamental role in human safety and resilience. The Abruzzo region (central Italy) underwent to a Mw 6.3 seismic event, in April 2009, that interested L’Aquila city (the county seat of the region) and many villages in the surrounding area. A first soil gas survey including radon (²²²Rn) and thoron (²²⁰Rn) measurements was accomplished soon after the main shock, in an area of ~24 km² a few kilometers away from L’Aquila city. Results highlighted the spatial influence of the active tectonic on gas migration towards the surface. The area was investigated again in spring 2016, both to evaluate the natural degassing during a period without further meaningful earthquakes and to verify the presence of faults supposed after the previous survey results. Comparing data from the two surveys, a variation in the ²²²Rn/²²⁰Rn ratio was observed, suggesting different sources (deep or superficial) of gas degassing strictly correlated with the temporal variation in soil vertical permeability. Furthermore, the results infer a new structural system different from that known in the literature. Full article

The evaluation of the structural behaviour of iconic historic buildings represents one of the most current structural engineering research topics. However, despite the various research works carried out during recent decades, several issues still remain open. One of the most important aspects is related to the correct reconstruction of the complex geometries that characterise this type of construction and that influence structural behaviour, especially in the presence of the horizontal loads caused by seismic action. For these reasons, different techniques have been proposed based on the use of laser scanners, Unmanned Aerial Vehicles (UAVs), and terrestrial photogrammetry. At the same time, several analysis methods have been developed that include the use of linear and non-linear approaches. In this present paper, the seismic performance of the Santa Maria Novella basilica and Santa Maria di Collemaggio basilica (before the partial collapse due to the 2009 L’Aquila earthquake) were investigated in detail by means of several numerical analyses. In particular, a series of non-linear time history analyses (NTHAs) were carried out, as reported in the Italian Building Code. To represent the non-linear behaviour of the main structural elements, smeared cracking (CSC) constitutive law was adopted. The geometry of the structures was reconstructed from a complete laser scanner survey of the churches, in order to consider all the intrinsic irregularities that characterise the heritage buildings. Finally, a comparison between the structural behaviour of the two case studies was carried out, highlighting the differences and similar aspects, focusing on possible collapse mechanisms and the identification of the most critical structural elements represented, in both cases analysed, by the main pillars of the transept. Full article

This paper illustrates the outcomes of a third-level Seismic Microzonation project carried out in pilot areas of the Municipality of L’Aquila, Italy, an area characterized by recent strong seismic activity (6 April 2009 Mw 6.3 earthquake and central Italy 2016 seismic sequence—Mw 6.0 and 6.5 events). The primary aim was to develop numerical maps for urban and land planning to mitigate seismic risk, in line with the guidelines of the Italian Civil Protection Department. The local amplification assessment was organized through various sequential and/or parallel activities, including geotechnical and geophysical investigations and characterization, seismic input and numerical code selection, acquisition of 2D microtremor arrays, and comparison between 1D and 2D numerical modeling of seismic site response. This case study introduces several innovations to the microzonation procedures outlined in current Italian and European regulations, such as the use of microtremor arrays to assess a reliable subsoil model and a new procedure for associating amplification factors to each microzone. The results obtained are significant both for the detailed seismic characterization of the territory and for providing methodological indications useful for similar future studies. The use of 2D models is integrated into the flowchart for producing third-level microzonation maps, offering valuable tools within the framework of urban and land management from a perspective of territorial sustainability. Full article

This paper describes the first results of the application of an innovative methodology for the development of a walkability overall index for urban street infrastructure, aimed at the application of urban design techniques to improve the urban form and its use by pedestrians. The general objective of the research is to identify the performance of the current city walkable network, to structure public policies and strategies consistent with it aimed at rebalancing settlements and infrastructure, and above all at the development of active mobility. The methodology defined integrates three approaches on walkability analysis: geometric–morphological, proximity, and sociality. In this paper, the analysis process related to the geometric–morphological component and partly to that of proximity will be described. It will be applied to the case study of the city of L’Aquila (Italy), a city undergoing reconstruction after the 2009 earthquake. From the first results of the application of the methodology to the case study, it emerges that the urban area analyzed is not capable of hosting walkable infrastructures unless urban design interventions are aimed at structuring an efficient network of pedestrian paths. In the future development of the study, it is expected to conclude the analysis of the proximity and social components, the other two groups of analysis considerations for walkability, which will complete the experimentation of the general methodology. Full article

In the field of seismic risk assessment, the estimation of human casualties is an important task for medical and relief agencies to develop preparedness and emergency management actions. The process of calculating casualties involves several factors along with the associated uncertainties. Despite its complexity and the limited quality and availability of data, many studies have been devoted to this topic in recent decades, but additional effort is required to better analyze these studies by also comparing the results they provide. In the present paper, an extensive literature overview of the main models proposed to estimate casualties is reported. Further, the main factors involved in the available Casualty Estimation Models are also analyzed by analyzing loss scenarios related to two strong Italian earthquakes (1980 Irpinia–Basilicata and 2009 L’Aquila). Comparing estimated vs. collected data, it is found that, in addition to the damage level, both the building material and the occupancy rate at the time of the event significantly impact the estimation of human casualties. As for the occupancy rate, based on the data on the daily life of citizens collected by the Italian Institute of Statistics, the occupancy rate functions for Italian residential building stock are derived and discussed. 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

Purpose: This study investigated the impact of the COVID-19 pandemic on mental health, quality of life, and family functioning in a sample of the general female population, exploring difficulties encountered in managing family and work responsibilities and burden of care when taking care of a loved one. This study was, moreover, aimed at investigating factors capable of influencing severe depressive symptomatology in the context of socio-demographics, traumatic events, individual vulnerability, and family functioning. Method: The sampling method used in this research was non-probability sampling. The survey took place during a Hospital Open Weekend (8–10 October 2021) organized by the National Gender Observatory on Women’s Health “Fondazione Onda” on the occasion of the World Mental Health Day. Results: A total of 211 women were interviewed (mean age = 35.6, 53% living alone, more than 15% with financial difficulties, 47% exposed to the 2009 L’Aquila earthquake). More than 50% of the sample reported a higher complexity in managing their lives during the COVID-19 pandemic compared to their previous routine, with no statistically significant differences between working women and non-workers, although the latter obtained higher scores for depressive symptomatology and poorer quality of life. Compared to non-caregivers, female caregivers (22.3%) in charge of the care of loved ones affected by physical (10.9%) or psychiatric disabilities (11.4%) complained of a poorer quality of life, especially in general health perception (p = 0.002), physical function (p = 0.011), role limitations related to physical problems (p = 0.017), bodily pain (p = 0.015), mental health (p = 0.004), and social functioning (p = 0.007). Women caring for people affected by mental disorders seemed to experience a more significant worsening in vitality (p = 0.003) and social functioning (p = 0.005). Approximately 20% of the total sample reported severe depressive symptomatology. Previous access to mental health services (O.R. 10.923; p = 0.000), a low level of education (O.R. 5.410; p = 0.021), and difficulties in management of everyday lives during the COVID-19 pandemic (O.R. 3.598; p = 0.045) were found to be the main variables predictive of severe depressive psychopathology. Old age, good problem-solving skills, and ability to pursue personal goals were identified as protective factors. Conclusions: The COVID-19 pandemic underlined the need for support amongst emotionally vulnerable women with pre-existing mental health conditions, partly reflecting the cumulative effects of traumas. Full article

The probability distribution of the interevent time between two successive earthquakes has been the subject of numerous studies for its key role in seismic hazard assessment. In recent decades, many distributions have been considered, and there has been a long debate about the possible universality of the shape of this distribution when the interevent times are properly rescaled. In this work, we aim to discover if there is a link between the different phases of a seismic cycle and the variations in the distribution that best fits the interevent times. To do this, we consider the seismic activity related to the $M_w$ 6.1 L’Aquila earthquake that occurred on 6 April 2009 in central Italy by analyzing the sequence of events recorded from April 2005 to July 2009, and then the seismic activity linked to the sequence of the Amatrice-Norcia earthquakes of $M_w$ 6 and 6.5, respectively, and recorded in the period from January 2009 to June 2018. We take into account some of the most studied distributions in the literature: q-exponential, q-generalized gamma, gamma and exponential distributions and, according to the Bayesian paradigm, we compare the value of their posterior marginal likelihood in shifting time windows with a fixed number of data. The results suggest that the distribution providing the best performance changes over time and its variations may be associated with different phases of the seismic crisis. Full article

The recent seismic events in Italy, including the earthquakes in L’Aquila in 2009 and central Italy in 2016, have significantly impacted the historical centers of small and medium-sized cities. These events directly affected their ancient masonry building heritage, resulting in severe damage. In order to minimize the risk of collapses and prevent further harm to people and structures until restoration efforts can be carried out, provisional post-seismic shorings have been extensively employed. These occurrences motivated several studies focused on the selection and assembly of post-seismic shorings, considering the various rigid failure mechanisms that may occur in a wall or section of an ancient masonry building. Yet, thus far, the critical considerations concerning the disassembly of these shorings, which significantly influence the repair process of a compromised structure from safety, organizational, and economic perspectives, have been overlooked. This research endeavors to establish a protocol for the dismantling of provisional shorings. To this end, a preliminary risk assessment tool has been devised, furnishing a safety index that correlates with the level of risk associated with shoring removal, along with corresponding risk categories. The study recommends preliminary interventions, categorized as mandatory or optional, to mitigate the risk prior to shoring removal. Furthermore, specific guidelines are provided based on the assessed risk level indicated by the safety index. To illustrate the application of this risk assessment tool, a case study involving an ancient masonry building in L’Aquila is presented. Full article