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Critical evaluation of Italian strong motion data and comparison to NGA ground motion prediction equations
Get PDFWe describe an Italian database of strong ground motion recordings and databanks delineating conditions at the instrument sites and characteristics of the seismic sources. The strong motion database consists of 236 corrected recordings from 86 earthquakes and 101 recording stations. Uncorrected recordings were drawn from public web sites and were processed on a record-by-record basis using a procedure utilized in the Next-Generation Attenuation (NGA) project to remove instrument resonances, minimize noise effects through low- and high-pass filtering, and baseline correction. The number of available uncorrected recordings was reduced by 52% (mostly because of s-triggers) to arrive at the 236 recordings in the database. The site databank includes for every recording site the surface geology, a measurement or estimate of average shear wave velocity in the upper 30 m (Vs30), and information on instrument housing. Of the 86 sites, 39 have on-site velocity measurements (17 of which were performed as part of this study using SASW techniques). For remaining sites, we estimate Vs30 based on measurements on similar geologic conditions where available. Where no local velocity measurements are available, correlations with surface geology are used. Source parameters are drawn from databases maintained (and recently updated) by Istituto Nazionale di Geofisica e Vulcanologia and include hypocenter location and magnitude for small events (M < 5.5) and finite source parameters for larger events.Ground motion prediction equations (GMPEs) have recently been developed in NGA project that are intended for application to shallow crustal earthquakes in tectonically active regions. We investigate the compatibility of those models with respect to magnitude-, distance-, and site-scaling implied by Italian strong motion data. This is of interest because (1) the Italian data is principally from earthquakes in extensional regions that are poorly represented in the NGA dataset and (2) past practice in Italy has been to use local GMPEs based on limited data sets which cannot resolve many source, path, and site effects known to be significant. We find that the magnitude scaling implied by the Italian data is compatible with the NGA relations. However, the Italian data attenuate faster than implied by the NGA GMPEs at short periods, and the differences are statistically significant for three of four relations. Three regression coefficients are re-evaluated for the three affected NGA GMPEs to reflect the faster attenuation; a constant term, a geometric spreading and anelastic attenuation term, and a source depth term. The scaling of ground motion with respect to site shear wave velocity is consistent between the NGA models and Italian data. Moreover, the presence of nonlinearity in the Italian data is confirmed and found to be generally compatible with what is provided by NGA site terms. The scatter of Italian data is much higher than in the NGA models, although only the intra-event error is sufficiently well established by the data to justify modification of NGA models. On the basis of these findings, we recommend that NGA relations, with the aforementioned minor modifications, be used to evaluate median ground motions for seismic hazard analysis in Italy
Prediction of structural response in reinforced concrete frames subjected to earthquake ground motions
No full textThis paper deals with the prediction of both force-based response measures and displacement-based response measures of different configurations of four story reinforced concrete frame buildings, with and without infill walls, and designed with different strength characteristics. The prediction is performed via statistical relationships between ground-motion intensity measures (IMs) and various engineering demand parameters (EDPs). The relationship is built on data obtained from nonlinear dynamic analyses of the frames subjected to one hundred strong motion records. The EDPs considered are maximum base shear, maximum story shear, maximum overturning moment, peak (over time) inter-story drift ratio, maximum (over all stories) peak inter-story drift ratio and roof drift ratio. Copyright © (2010) by Earthquake Engineering Research Institute
A Comparison of NGA Ground-Motion-Prediction Equations to Italian Data
No full textGround-motion prediction equations (GMPEs) have recently been developed in the Next Generation Attenuation (NGA) project for application to shallow crustal earthquakes in tectonically active regions. We investigate the compatibility of those models with respect to magnitude scaling, distance scaling, and site scaling implied by Italian strong motion data. This is of interest because (1) the Italian data are principally from earthquakes in extensional regions that are poorly represented in the NGA dataset, and (2) past practice in Italy has been to use local GMPEs based on limited datasets that cannot resolve many significant source, path, and site effects. We find that the magnitude scaling implied by the Italian data is compatible with four NGA relations. However, the Italian data attenuate faster than implied by the four NGA GMPEs at short periods; the differences are statistically significant. Comparison with the fifth one was not possible because it was developed for rock conditions only. Three regression coefficients are reevaluated for the four NGA GMPEs to reflect the faster attenuation: a constant term, a term controlling the slope of distance attenuation, and a source fictitious depth term. The scaling of ground motion with respect to site shear wave velocity is consistent between the NGA models and Italian data. Moreover, the data are found to contain a nonlinear site effect that is generally compatible with NGA site terms. The intraevent scatter of Italian data is higher than in the NGA models, although interevent scatter is comparable to NGA recommendations when the faster distance attenuation is considered. On the basis of these findings, we recommend using the NGA relations, with the aforementioned minor modifications, to evaluate ground motions for seismic hazard analysis in Italy
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Spettri di piano in edifici a telaio in c.a.
No full textLa progettazione di edifici in cemento armato siti in aree caratterizzate da alti valori di pericolosità sismica, può produrre in alcuni casi delle strutture altamente resistenti, che pur essendo capaci di sopportare le azioni sismiche sono sottoposte ad elevati livelli di domanda in accelerazione. Gli elementi non strutturali ed i contenuti in generale di questi edifici possono di conseguenza, se non adeguatamente progettati, subire importanti danneggiamenti. Per motivi legati al loro costo di riparazione o all’importanza stessa associata al loro utilizzo all’interno dell’edificio, vedi il caso degli ospedali, la valutazione delle azioni sismiche su questi elementi può risultare quindi di grande interesse. Scopo del lavoro è lo studio degli spettri di piano in accelerazione che si possono osservare su diversi tipi di edifici a telaio in cemento armato. I casi studio analizzati si differenziano per il numero di piani, per la diversa distribuzione delle tamponature e per il valore di intensità dell’azione sismica a cui sono sottoposti. I risultati ottenuti con le analisi dinamiche sono in fine discussi e confrontati con gli spettri calcolati utilizzando le equazioni proposte nell’Eurocodice 8
PRELIMINARY COMPARISON OF GROUND MOTIONS FROM EARTHQUAKES IN ITALY WITH GROUND MOTION PREDICTION EQUATIONS FOR ACTIVE TECTONIC REGIONS
No full textEmpirical ground motion prediction equations utilized in Italy are based on local databases of recordings from Italian and/or European earthquakes, which are generally shallow crustal events. For events of this type, alternative ground motion prediction equations are used elsewhere in the world that are based on a much larger data inventory. The implicit assumption associated with the use of local (Italian/European) relations is that the characteristics of the local ground motions are different from those in other tectonically active regions. We investigate whether such differences exist for the ground motion parameter of average peak horizontal acceleration. Italian data from predominantly normal fault shallow crustal earthquakes (M=5.1-6.9) recorded at distances up to 200 km are used to compare several key attributes of the Italian data to a well-known relation for worldwide active regions. One such attribute is site effects, for which we find a nonlinear rock-to-soil amplification that is similar to the worldwide model. This nonlinear site response is a significant finding of this study that had not been observed previously with European data. The other two attributes investigated are magnitude and distance scaling, for which some differences were observed from the worldwide model. However, the significance of those differences cannot yet be properly assessed due to apparent correlations between the magnitude- and distance-scaling parameters that are not yet fully understood
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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