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This paper explores and validates the use of ground shaking scenarios generated via 3D physics-based numerical simulations (PBS) for seismic fragility studies. The 2009 L’Aquila seismic event is selected as case-study application, given the availability of a robust and exhaustive post-earthquake database, gathering observed seismic damages detected on several building typologies representative of the Italian built environment, and of a validated numerical model for PBS ground shaking scenarios. Empirical fragility curves are derived as a function of different seismic intensity measures, by taking advantage of an improved statistical technique, overcoming possible uncertainties in the resulting estimates entailed by data aggregation. PBS-based fragility functions are compared to the corresponding sets of curves relying on updated ShakeMaps. The predictive capability of the adopted simulation strategies is then verified in terms of seismic damage scenarios, by respectively coupling PBS- and ShakeMap-based fragility models with the corresponding ground shaking scenarios. Comparison of observed and predicted damage distributions highlights the suitability of PBS for region-specific seismic vulnerability and risk applications.

In this paper, empirical fragility curves for reinforced concrete buildings are derived, based on post-earthquake damage data collected in the aftermath of earthquakes occurred in Italy in the period 1976–2012. These data, made available through an online platform called Da.D.O., provide information on building position, building characteristics and damage detected on different structural components. A critical review of this huge amount of data is carried out to guarantee the consistency among all the considered databases. Then, an in-depth analysis of the degree of completeness of the survey campaign is made, aiming at the identification of the Municipalities subjected to a partial survey campaign, which are discarded from fragility analysis. At the end of this stage, only the Irpinia 1980 and L’Aquila 2009 databases are considered for further elaborations, as fully complying with these criteria. The resulting database is then integrated with non-inspected buildings sited in less affected areas (assumed undamaged), to account for the negative evidence of damage. The PGA evaluated from the shakemaps of the Italian National Institute of Geophysics and Volcanology (INGV) and a metric based on six damage levels according to EMS-98 are used for fragility analysis. The damage levels are obtained from observed damage collected during post-earthquake inspections through existing conversion rules, considering damage to vertical structures and infills/partitions. The maximum damage level observed on vertical structures and infills/partitions is then associated to the whole building. Fragility curves for two vulnerability classes, C2 and D, further subdivided into three classes of building height, are obtained from those derived for specific structural typologies (identified based on building height and type of design), using their frequency of occurrence at national level as weights.

The homogeneity of standard Italian railway stations in terms of period of construction (second half of the 19th century), architectural and structural features, typical dimensions and morphology (...

This paper illustrates the derivation of an empirical fragility model for residential unreinforced masonry (URM) buildings, calibrated on Italian post-earthquake damage data and compatible with the key features of the Italian national seismic risk platform. Seismic vulnerability is described by fragility functions for three vulnerability classes, then refined based on the building height. To this aim, a clustering strategy is implemented to merge predefined building typologies into vulnerability classes, based on the similarity of the observed seismic fragility. On the other side, a specific procedure is built up to determine the vulnerability composition of the exposed URM building stock, starting from national census data. The empirically-derived model was implemented into the national seismic risk platform and used, together with other vulnerability models, for assessing seismic risk in Italy. The results presented in this paper, consisting of refined typological fragility curves and fragility curves for vulnerability classes, can be also exploited for estimating both expected seismic damage and risk in sites with similar seismic hazard and building inventory.

Κατά τους βυζαντινούς χρόνους εντοπίζονται πολλά παραδείγματα συνωμοσιών μέσω των οποίων αξιωματούχοι, αυτοκράτορες και αυτοκράτειρες θέλησαν να σκοτώσουν ή να απομακρύνουν από την πολιτική ζωή τους αντιπάλους τους. Παρότι τον έβδομο αιώνα η αυτοκρατορική διαδοχή έλαβε δυναστικό χαρακτήρα, δεν επικράτησε ηρεμία στο εσωτερικό του κράτους, καθώς εκδηλώθηκαν πολυάριθμα κινήματα. Με βάση τη νομοθεσία και την κυρίαρχη πολιτική ιδεολογία ο αυτοκράτορας είχε το δικαίωμα να τιμωρήσει όσους απειλούσαν την εξουσία του, ενώ αν κυβερνούσε ως τύραννος μπορούσε να ανατραπεί. Ουσιαστικά, η τελευταία αντίληψη νομιμοποιούσε όχι μόνο το δικαίωμα των πολιτών να αντιδρούν απέναντι στην ασύνετη διοίκηση, αλλά και στις σφετεριστικές δραστηριότητες.Ανάμεσα στα ανατρεπτικά κινήματα που πραγματοποιήθηκαν στη βυζαντινή αυτοκρατορία, κυρίαρχη θέση είχαν οι στάσεις/εξεγέρσεις. Επίσης, οι σφετεριστές συχνά επέλεγαν τις συνωμοσίες για να υλοποιήσουν τα ανατρεπτικά σχέδιά τους. Οι συνωμότες ήταν συνήθως μια ομάδα ανώτερων αξιωματούχων, οι οποίοι οργανώνονταν και δρούσαν κάτω από απόλυτη μυστικότητα προκειμένου να επιτύχουν τον σκοπό τους. Είναι προφανές ότι η συνωμοσία γινόταν γνωστή στους κατοίκους της αυτοκρατορίας είτε μετά την καταστολή της είτε μετά τη θετική έκβασή της. Οι αλλαγές στην πολιτική ζωή, ύστερα από την εκδήλωση ή την εξουδετέρωση συνωμοσίας υπήρξαν σημαντικές. Τα μέλη της συνωμοσίας, όταν κατόρθωναν να απομακρύνουν τον ηγεμόνα από την εξουσία, φρόντιζαν να ανεβάσουν στον θρόνο εκείνον που ίδιοι είχαν επιλέξει. Οι αυτοκράτορες, μόλις ανακάλυπταν την ύπαρξη συνωμοσίας, επιχειρούσαν να εξουδετερώσουν τους αντιπάλους τους, τιμωρώντας τους δημόσια.Τα στοιχεία που υπάρχουν στις πηγές δείχνουν ότι οι συνωμοσίες κατείχαν ξεχωριστή θέση στην πολιτική ζωή του Βυζαντίου. Αυτή η άποψη επιβεβαιώνεται κυρίως από το γεγονός ότι δεν εξυπηρετούσαν μόνο τις βλέψεις των εκάστοτε σφετεριστών, αλλά και τα σχέδια των αυτοκρατόρων. Εξίσου σημαντικό ήταν ότι οι συνωμοσίες οργανώνονταν ευκολότερα και δεν δίχαζαν τον λαό. Οι παραπάνω λόγοι, αναμφίβολα, παρακίνησαν σε κάθε εποχή τους Βυζαντινούς να επιλέξουν τη συγκεκριμένη πολιτική τακτική για να αντιδράσουν, να εξυπηρετήσουν τα συμφέροντά τους και να υλοποιήσουν τις φιλοδοξίες τους.

Endometrial glassy cell carcinoma (EGCC) is a rare neoplasm, accounting for 0.5% of the carcinomas in the endometrium, composed of cells with granular eosinophilic or amphophilic cytoplasm, giving it a ground glass appearance. Till date, only 14 cases of this carcinoma have been reported. In this report, we have described a case of EGCC to help define standard diagnostic criteria and better understand the course, ideal treatment, and accurate prognosis of this disease. We report a case of a 64-year-old woman diagnosed with EGCC after an abnormal pap smear. She underwent a hysteroscopy, which led to the histological diagnosis. Laparotomic total hysterectomy and bilateral salpingo-oophorectomy were performed with pelvic lymphadenectomy and peritoneal and omental biopsies. Final pathological examination confirmed the initial diagnosis. Pelvic nodes removed during surgery and peritoneal and omental biopsies were negative for tumor cells. Treatment was considered appropriate and the patient did not require additional therapies. She was subsequently assigned to clinical follow-up and is alive, with no evidence of the disease.

The Department of Civil Protection (DPC), in compliance with the EU decision 1313/2013 and at the request of the Sendai Framework for Disaster Risk Reduction 2015–2030 to update the disaster risk assessments by various countries, released the latest National Risk Assessment for Italy at the end of 2018. Specifically, as regards the seismic risk assessment, six research units belonging to two centres of competence of the DPC collaborated under its guidance to update the risk maps of the Italian residential heritage. This extensive collaboration complied with the recent Italian code for Civil Protection, which requires a broad scientific consensus for risk assessment. During this research activity, six fragility models were developed, according to some common criteria (four for masonry buildings and two for RC buildings). These models were then implemented by the DPC for the definition of the national seismic risk. Within this context, the aim of this paper is to evaluate the risk results provided by these models, compare their features, and assess and validate their prediction capabilities. In particular, this paper shows the comparison of predicted and observed damage scenarios and consequences on building stock and the population of two seismic events, i.e. L’Aquila 2009 and Amatrice 2016. Furthermore, the paper provides some interesting damage and risk predictions at a national level. Overall, the forecasts and comparisons made in this study demonstrate the validity of the approach adopted by the DPC for the assessment of national seismic risk.

This paper describes the multivariate statistical model of the structure-related modelling uncertainty, developed with reference to reinforced concrete, masonry, steel, and seismically isolated buildings, within the framework of the RINTC project. The model describes the variability of material properties as well as the uncertainty associated with the adopted response models. Specific aspects of each structural typology are also discussed, with a focus on the statistical dependence of the random variables in the model. Finally, the paper describes also the efficient sampling procedure adopted. Effect of model uncertainty on response for each typology are discussed in the corresponding papers within this special issue dedicated to the RINTC project.

Post-earthquake damage data represent an invaluable source of information for the seismic vulnerability assessment of the exposed building stock, as they are a direct evidence of the actual buildings’ performance under real seismic events. This paper exploits a robust and homogeneous database of damage data collected after the 2009 L’Aquila (Italy) earthquake, to derive damage probability matrices for several building typologies representative of the Italian building stock. To this aim, the first part of the work investigates several issues related to the definition of damage to be associated with each inspected building. Different approaches and damage conversion rules are applied, pointing out advantages and weaknesses of each one. Considering the widespread seismic damage observed on masonry infill panels and partitions of reinforced concrete constructions, the impact of this type of non-structural damage on empirical damage and functional loss distributions is explored. The second part of the study proposes different possible interpretations of the repartition of the observed damage in the different damage levels, showing in some cases a bimodal trend. Two novel hybrid procedures are outlined and compared with the classical binomial approach for predicting the subdivision of damage in the different levels. The application of the proposed methodologies to the different building typologies allows the selection, for each one, of the method providing the best fit to empirical results. The parameters required for the application of the optimal approach are reported in the paper, so that results can be used for forecasting the expected seismic damage in sites with similar seismic hazard and exposed buildings.

The companion paper by Rota and Rosti (Bull Earthq Eng, 2017) illustrates a methodology for comparing PSH results with historical macroseismic observations at different scales, in terms of mean damage. This paper presents examples of application of the methodology, at the different considered scales, to the South-East quarter of France. This moderate seismicity region is characterised by a long history of civilization, which makes macroseismic observations available for a long time span, although they are highly approximated measures of the seismic action and they are affected by significant uncertainties. The first scale of application presented is at a single site, i.e. the city of Annecy. This example shows that, despite the seismic history of this city is characterised by a significant number of macroseismic observations spanning over a long time period, they mostly consist of very low intensity values and hence the comparison at a single site is not very meaningful. Therefore, the comparison is carried out on a set of seven aggregated sites, well distributed in the region of interest, providing interesting results and suggesting the opportunity of extending the comparison at an even larger scale. The comparison at the regional scale also allows some interesting observations, although it is obviously able to only provide general (average) indications on the PSH results. These comparisons were aimed at showing the applicability of the proposed methodology, pointing out advantages and drawbacks of the different application scales.

The need for verifying and/or validating the results of probabilistic seismic hazard studies has become evident, despite the absence of generally accepted methods for judging such results. This paper proposes a methodology for comparing the results of PSH with historical macroseismic observations, at different scale levels. The selected metric of the comparison is the mean damage, i.e. the average annually expected damage. Hence, a procedure for converting macroseismic observations and PGA levels, for which PSH estimates are provided, into mean damage values is first presented. The procedure is based on the macroseismic method for converting intensities into mean damage values, whereas it takes advantage of fragility curves (representative of the seismic vulnerability of the building stock at the time of historical observations) to transform the rates of occurrence of PGA values into the equivalent quantity in terms of mean damage. A methodology for site-specific comparison is first outlined. To overcome some of the limitations of the comparison at a single site, two procedures for aggregating several sites by sampling in space are then presented, with the aim of enlarging the available macroseismic dataset. Finally, a procedure for the comparison at the regional level is discussed. Applications of the proposed methodologies will be discussed in a companion paper (Rosti and Rota in Bull Earthq Eng, 2017).

La valutazione del rischio sismico a scala territoriale è fondamentale per la gestione dell’emergenza post-terremoto, quantificazione delle perdite socio-economiche dovute a terremoti futuri, definizione di strategie di mitigazione del rischio, ottimizzazione di piani di intervento. Affinché le conseguenze dovute a futuri eventi sismici possano essere efficacemente mitigate, è necessario disporre di stime di rischio accurate e affidabili. In questo contesto, la difficoltà principale è legata alla definizione del rischio stesso, che, risultando dalla convoluzione di pericolosità, esposizione e vulnerabilità, richiede il coinvolgimento di diverse discipline scientifiche. In questo lavoro, modelli di vulnerabilità per edifici residenziali in muratura e c.a., derivati empiricamente sulla base di dati di danno post-terremoto, sono implementati nella piattaforma nazionale del rischio sismico, al fine di produrre stime di rischio a scala territoriale. Diversi sono i casi studio presentati, focalizzati sulla valutazione del rischio incondizionato. I risultati sono mostrati per diversi tipi di conseguenze, quali vittime, perdite economiche, impatto in termini di abitazioni inagibili e crollate e numero di sfollati.

Questo lavoro presenta curve di fragilità empiriche per il costruito esistente in c.a., da utilizzare per la valutazione del rischio sismico a scala territoriale. Le curve sono state derivate elaborando statisticamente i dati di danno postterremoto raccolti nella piattaforma Da.D.O., utilizzando l’accelerazione di picco al suolo (PGA) stimata da shakemap come misura di intensità per la caratterizzazione dello scuotimento. Gli edifici in c.a. sono classificati in quindici tipologie edilizie, identificate sulla base del numero di piani (da 1 a 5 piani) e tipo di progettazione (edifici progettati per soli carichi gravitazionali, per carichi sismici pre-1981 e post-1981). In primo luogo, le curve di fragilità sono state derivate per le tipologie edilizie identificate e per cinque livelli di danno della EMS-98, tenendo conto del danno osservato su componenti strutturali e non strutturali. Successivamente, si sono derivate curve di fragilità per due classi di vulnerabilità a vulnerabilità decrescente e tre classi di piano, pesando le curve di fragilità tipologiche sulla base della composizione del costruito esistente.

In a country with high seismic risk, such as Italy, the activities to raise awareness about the seismic risk are of primary importance. The Inarcassa Foundation, the National Council of Engineers and the National Council of Architects with the scientific support of the Superior Council of Public Works, the Italian Civil Protection Department, the Conference of Italian University Rectors and the Laboratories University Network of Earthquake Engineering have launched the national awareness campaign, named "Diamoci una scossa!". As part of this campaign, technical and informational visits to residential buildings were carried out by architects or engineers expert in seismic risk. A special form, called “Diamoci una scossa!” form, was compiled by the technicians during technical-information visits. This form was prepared starting from similar forms already used in Italy, such as the AeDES form, the Cartis Building form and the CLE US1 form. On the basis of the acquired data related to the current seismic risk, the construction age and the vulnerabilities of buildings, it was possible to associate a color to the building (green / yellow / red). This color provides generic indications on the possible risk class of the building according to the classification provided by the Sisma Bonus fiscal benefits and on the urgency for a in-depth building assessment according to seismic code. The present work, after a brief description of the awareness campaign and related activities, deal with the "Diamoci una scossa!" form and the criteria adopted for assigning the color based on the data collected regarding each specific building.

Most of Italian railway stations date back to the second half of the 19th century, when the railway network was created. Although originally belonging to different companies and in spite of some modifications occurred over the years, most of these stations are masonry buildings conceived according to similar standards, with typical dimensions and morphology mostly depending on the expected traffic of passengers and goods. The common structural features of these buildings allow grouping them into building typologies, characterized by a similar structural response. This is relevant for the assessment of the seismic vulnerability of these structures, whose damage or collapse could lead to critical consequences, due to the potentially high number of victims and to the risk of interruption of critical lines. Nonlinear global analyses by equivalent-frame macroelement modelling and linear kinematic analyses of possible local failure modes have been used to assess the seismic response of building prototypes representative of the most common architectural typologies. A logic tree approach was used to consider uncertainties in mechanical properties, geometry and construction details for the derivation of fragility curves for different limit states.

Several building codes propose methodologies to account for epistemic uncertainties in the seismic assessment of masonry buildings by selecting a knowledge level and reducing material strengths by means of the associated value of the confidence factor. Previous works showed that, in the case of masonry structures, this approach has various limitations, such as the lack of proper consideration of experimental tests performed. This article focuses on the issue of imperfect knowledge on material properties of existing masonry buildings and proposes a probabilistic methodology for the assessment, based on Bayesian updating of mechanical properties. The use of a Bayesian approach allows to update the values of the material properties assumed a priori as knowledge on the building increases, by taking into account all the experimental information gathered during the assessment process. A large number of simulated assessments is carried out and the values of the confidence factors on material properties are defined through the comparison between the obtained results and those of the reference structure, assumed to be perfectly known. These factors are useful in a more general framework for the assessment of masonry buildings accounting for different sources of uncertainty.

An experimental campaign aiming at investigating the seismic performance of unreinforced masonry low-density autoclaved aerated concrete blocks is presented. After characterization tests on blocks, mortar and wallettes, in-plane cyclic tests on six full-scale unreinforced masonry piers were performed to obtain a reliable description of the lateral cyclic behavior. Information regarding the displacement capacity and the correlation between experimental and analytical strengths were derived. The results show a limited in-plane displacement capacity of piers, strongly depending on the applied vertical load, and a good correlation between experimental and calculated lateral strengths. At the end of the cyclic tests, the residual vertical strength of some walls was also directly checked.

A suitable characterisation of seismic input at the sites where damage is reported is a key aspect of the study of empirical seismic fragility. The availability of a shakemap, specifically derived for the event of interest from recorded ground motions, allows considering site conditions, spatial variability and possible directivity effects. Whenever this is not available, alternative solutions must be considered, such as for example the use of ground motion prediction equations (GMPEs) or the generation of conditional spatially correlated ground motion random fields (CSCRFs). Each of these approaches bears several uncertainties, which obviously have an effect on the derived empirical damage probability matrices. This paper explores issues and procedures related with the ground motion characterisation and assesses their impact on empirical damage distributions derived from a comprehensive post-earthquake damage database, compiled after the 2009 L'Aquila (Italy) seismic event. Several GMPEs are qualitatively and quantitatively ranked with respect to the available accelerometric data and the damage probability matrices obtained with the best performing GMPE are then compared with results obtained using more refined ground motion characterisations.

Uterus didelphys accounts for 13% of uterine anomalies and has been correlated with preterm delivery and fetal malpresentation at delivery. A 37-year-old pregnant woman reported a spontaneous pregnancy in the right horn of a uterus didelphys. The course of the pregnancy was complicated by gestational diabetes, but no miscarriage threat or preterm delivery threat was reported during this pregnancy. She arrived at our division, in labor, at 39.2 gestational weeks’. She delivered by cesarean section due to failure to progress at 5 cm. Her post-operative course was uneventful. Vaginal delivery could be a safe option and the induction of labor or the use of oxytocin could be helpful in such cases, but recommended doses and labor time should be evaluated, so cesarean section is to date the most frequent delivery route in uterus didelphys at term.

The unreinforced masonry (URM) buildings designed to be conforming with the Italian building code, as illustrated in the companion paper, were analyzed by performing time-history analyses on models...

Heterotopic pregnancy is a rare condition, and its recognition could be highly challenging. We decided to report our cases, in which the evaluation of beta Human Chorionic Gonadotropin (HCG) level ...

Experimental campaigns carried out in the past showed that the presence of truss bed-joint reinforcement provides a general improvement to the performance of masonry panels subjected to horizontal actions. The truss-like elements are effective in improving resistance and reducing damage and, therefore, they enhance the displacement capacity. The experimental tests available in the literature, performed on prototypes in different scale or in small number compared to the possible combinations of slenderness, axial load and boundary conditions, hardly allow drawing quantitative conclusions on the real benefit of the presence of horizontal reinforcement to the performance improvement for a specific masonry type. The experimental campaign presented in this paper includes a set of in-plane cyclic tests on Autoclaved Aerated Concrete (AAC) masonry panels with thin horizontal and vertical joints filled with thin layer mortar, made both in unreinforced and bed-joint reinforced masonry with flat-truss bed-joint reinforcement. The direct comparison of the results, along with specific tests performed on wallettes made with the two different construction technologies, allows the assessment of the effectiveness of the horizontal reinforcement in enhancing the in-plane seismic performance of AAC masonry.

The choice of modelling strategy and analysis options has a significant influence on the results of the seismic assessment of existing buildings and therefore it is very important to have an idea of the dispersion in the results due to different hypotheses regarding the structural model. This paper concentrates on pushover analysis, considered as the reference method currently adopted by engineers for the seismic assessment of existing masonry buildings, and on the equivalent-frame macro-element approach, assumed to be a satisfactory compromise between computational effort and accuracy in the results. A logic tree approach is used to treat the different considered options, including the definition of the geometry of the equivalent frame, the distribution of loads among the masonry piers and on the horizontal diaphragms, the degree of coupling between orthogonal walls, the definition of the cracked stiffness of structural elements and the modelling of masonry spandrels. By assigning a value of probability to each end branch of the tree, the distribution of the peak ground acceleration corresponding to the selected limit states can be obtained and, from this distribution, a quantitative estimate (in probabilistic terms) of the effect of modelling uncertainties on the seismic response of masonry structures is derived.

Masonry walls constructed with lightweight AAC blocks and thin-layer mortar meet the increasingly strict requirements of energy efficiency and sustainability. In this sense, they represent an excellent solution for modern buildings, not only for external cladding but also as loadbearing elements. Despite the possible advantages of using lightweight AAC masonry, a specific assessment of its seismic performance is mandatory in order to set design recommendations allowing to reach safety levels consistent with those required for other masonry types complying with EN 1998 standard requirements. A comprehensive study on the seismic performance of unreinforced masonry buildings made of lightweight AAC was carried out in an integrated experimental-numerical approach. The experimental campaign provided the necessary information to setup a reliable numerical model to be extensively used to assess the seismic performance of a number of prototype AAC masonry buildings with different characteristics, by means of both linear and nonlinear static (pushover) analysis. The results of this systematic numerical assessment were eventually used to draft design recommendations, to set parameters (behaviour factors) to be used in linear analysis and to calibrate rules for simple buildings. Mauerwerkswande aus Porenbetonblocken und Dunnbettmortel erfullen die zunehmend strengeren Anforderungen an Energieeffizienz und Nachhaltigkeit. Sie stellen in dieser Hinsicht eine exzellente Losung fur moderne Gebaude dar, nicht nur fur die Ausenverkleidung, sondern auch als tragende Bauteile. Trotz der Vorteile, die der Einsatz von Porenbetonmauerwerk bietet, ist eine spezifische Bewertung seines seismischen Verhaltens erforderlich, um Bemessungsempfehlungen festlegen zu konnen, die die Anforderungen der Norm EN 1998 erfullen. Unter Anwendung eines kombinierten experimentellen und numerischen Ansatzes wurde eine umfassende Studie des seismischen Verhaltens von unbewehrten Mauerwerksgebauden aus Porenbeton durchgefuhrt. Die Versuchsreihe lieferte die notwendigen Informationen fur die Entwicklung eines zuverlassigen Modells, das breit eingesetzt werden kann, um das Erdbebenverhalten einer Reihe von prototypischen Mauerwerksbauten aus Porenbeton mit unterschiedlichen Charakteristika sowohl durch lineare als auch nichtlineare statische (Pushover-) Analysen zu bewerten. Die Ergebnisse dieser systematischen numerischen Bewertung wurden schlieslich dazu verwendet, Bemessungsempfehlungen zu formulieren, Parameter (Verhaltensfaktoren) zur Verwendung in linearen Analysen festzulegen und Regeln fur einfache Gebaude aufzustellen.

Performance-based earthquake engineering, developed over the last decades for the design and assessment of other structures, can also be applied for masonry structures if the particularities of masonry are incorporated into the procedure. According to this methodology, structural performance can be assessed according to damage states which are identified through displacement/damage indicators. While various methods for the identification of limit states from the results of nonlinear static analyses exist, the identification of damage states from the results of nonlinear dynamic analyses is still uncertain. This article investigates a number of criteria allowing to identify the attainment of significant limit states from the results of time history analyses, in terms of appropriately identified response quantities. These criteria are applied to five building prototypes and their results are compared. A comparison with the limit states derived from nonlinear static analyses is also made.

An extensive experimental program was carried out at EUCENTRE, within a research project on the evaluation and reduction of the seismic vulnerability of stone masonry structures. The main part of the experimental program has been devoted to the shaking table tests on three full-scale, two-story, single-room prototype buildings made of undressed double-leaf stone masonry. The first building tested was representative of existing unreinforced stone masonry structures with flexible wooden diaphragms, without any specific anti-seismic design nor detailing. In the second and third buildings, strengthening interventions were simulated on structures theoretically identical to the first one, improving wall-to-floor and wall-to-roof connections and increasing diaphragm stiffness. In particular, in the third specimen, steel and r.c. ring beams were used to improve the diaphragm connection to the walls and collaborating r.c. slab and multi-layer plywood panels were used to stiffen floor and roof diaphragms, respectiv...

An extensive experimental campaign has been conducted at EUCENTRE to understand the dynamic behavior of historic stone masonry structures and evaluate the seismic performance of selected strengthening strategies, aimed at improving wall-to-floor connections and in-plane diaphragm stiffness. Shaking table tests were performed of full-scale two-storey buildings in undressed double-leaf stone masonry with timber floor and roof. A first prototype (Building 1), representing a vulnerable building without antiseismic detailing and devices, was tested showing a response characterized by in-plane distortion of the flexible diaphragms and local out-of-plane failure mechanisms. In Building 2 the wall-to-diaphragm connections were improved, providing only a moderate in-plane stiffening of the wooden diaphragms. When subjected to shake-table testing, the strengthened building showed a global type of structural response without the occurrence of out-of-plane mechanisms. In the present paper the strengthening interventi...

SUMMARY The current formulation of Eurocode 8 Part 3 and the Italian building code for the seismic assessment of existing buildings accounts for epistemic (knowledge-based) uncertainties by means of the identification of knowledge levels with associated values of the so-called confidence factors, applied only as a reduction of material strengths. This formulation does not always produce consistent results and it does not explicitly account for other sources of uncertainty. The paper proposes a probabilistic methodology for the quantification of appropriately defined factors, allowing consideration of the different sources of uncertainty involved in the seismic assessment of masonry buildings by means of nonlinear static analyses. This simple approach, also including an alternative formulation of the confidence factors related with material properties, allows to obtain results which are consistent with the acquired level of knowledge and correctly account for the different sources of uncertainty without requiring to carry out any stochastic nonlinear analysis. Copyright © 2013 John Wiley & Sons, Ltd.