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    • Energia assorbita e tecniche di consolidamento antisismico di edifici in muratura

    Duilio Benedetti

    During the last 15 years 18 simple masonry systems, scaled 1:2 and 1:1, have been tested by using a shaking table. The masonry systems were of different geometrical configurations and partly strengthened by various techniques, including hysteretic devices. For each masonry system and each shaking absorbed energies have been computed from recorded response signals and appropriate indices have been worked out in order to allow comparisons. These point out the positive effect induced by horizontal tendons in allowing a regular evolution of the response, without sudden stiffness decreases and the efficiency of hysteretic devices to control damage and increase available ductility.

    This paper is available in Italian only

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    • Concezione strutturale e risposta sismica delle strutture lignee di copertura

    Claudio Chesi, Maria Adelaide Parisi, Chiara Tardini

    In view of assessing the seismic vulnerability of timber roof structures, it is necessary to define evaluation criteria for the various elements and features that influence the structural response. Ths work focuses on the structural concept, particularly interesting because of the numerous existing solutions; indeed, these structures, originally conceived for vertical loads, may be more or less apt to respond to seismic action. With the classic tools of modal and response spectrum analysis the effect of the structural concept has been investigated, in order to define a basis for classification criteria. The aspects that appeared to affect positively the seismic response are a suitable association of the design parameters, according to the traditional construction practice, and the effectiveness of the connections that realize the threedimensionality of the structure.

    This paper is available in Italian only.

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    • «Il viadotto di silea in Veneto»: verifica sismica secondo la normativa italiana e l’eurocodice

    Gaetano Russo, Otello Bergamo, Luigi Damiani

    The design of an important viaduct in Treviso (a town in Venetian area) is here described. This struc- ture, called «Silea» Viaduct, was designed following the philosophy of the new prestational codes. The viaduct, built in 2007, has medium span and composite structure. In this paper the different safety level has been evaluated on the basis of National and European Codes. The structure is provided with viscous dampers and mechanical dampers to bidirectional earthquake excitation and the main parameters defining the seismic behaviour of seismically isolated bridges are investigated.

    This paper is available in Italian only.

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    • Aggiornamento delle mappe di rischio sismico in Italia

    Fabrizio Bramerini, Giacomo Di Pasquale

    Seismic risk maps updated on the basis of new data about real estate are presented in this paper. Previous maps were presented in 1996 by a specific workgroup appointed by Italian Civil Protection Department and they were used to make a list of municipalities at high seismic risk that were granted tax relief depending on vulnerability reduction interventions. Furthermore, those maps were updated with the hazard assessment developed after 1998. Real estate and population data resulted from Istat Census of 1991. In this updating, data from Istat Census of 2001 have been used, but hazard assessment and the methodology were the same of the previous maps, in order to evaluate the impact of a different structure of the real estate on risk assessment.
    All the evidence makes it clear that the distribution and the overall assessment confirm the previous evaluation based on 1991 data, in spite of a 9% real estate increment, from 1991 to 2001. Specific data processing has pointed out differences in structural characteristics of the real estate from 1991 and 2001 Istat Census, reducing its estimated vulnerability, in compensation of the exposure increment due to the real estate increment.

    This paper is available in Italian only.

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    • Nuovi strumenti per lo studio della risposta sismica di strutture irregolari in pianta

    Luigi Petti, Ivana Marino, Luca Cuoco

    SUMMARY – New tools for the analysis of the seismic behaviour of plan-asymmetric structures are herein presented and discussed. In particular, the concept of Polar Spectrum is firstly introduced to feasibly describe the spatial features of the seismic event. Limit domains are then used to investigate the non-linear behaviour of plan-asymmetric structures. The results obtained by the discussed procedure have been compared with non-linear dynamic analyses by using a benchmark structure.

    This paper is available in Italian only.

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    • Zone, griglie, o… stanze? Dalle «zone sismiche» al «room effect»: verso una nuova modalità nella determinazione del rischio sismico

    Paolo Rugarli

    Seismic zoning considered in the new Italian seismic code (D.M. 14-1-2008), and the pertinent definition of elastic response spectra to be used in design are critically revised and discussed, pointing out serious problems that may arise in the application of the relevant code rules and parameters. A comparison with ASCE-7 2005 United States standard is also performed. Finally, the target precision of elastic spectra resulting from such parameters is discussed, showing that a four digits computation may be misleading.

    This paper is available in Italian only.

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    • Analisi di stabilità dinamica di un movimento franoso utilizzando un modello semplificato applicando accelerogrammi generati e registrati

    Floriana Pergalani, Massimo Compagnoni

    In the paper the analyses, the results and the comparison performed on a landslide located in Costafiore in the municipality of Muccia (MC) are presented. The aim of the analyses has been to verify the pseudo-static and dynamic stability of the landslide, using two simplified models. In particular, for the pseudo-static analyses a code deriving by the method of Sarma /22, 23, 24, 25/ has been applied; for the dynamic analyses a code deriving by the method of Newmark /11/ has been used. To perform the dynamic analysis, it is necessary to have assessorgrams, in this project both recorded and synthetic accelerograms have been applied; so a comparison on the obtained results, in term of expected displacements, has been performed; therefore the influence of the two applied sets has been evaluated. The synthetic accelerograms have been calculated considering the results of the seismic hazard analyses performed by the Gruppo di Lavoro 2004 /9/, in particular the acceleration elastic response spectra, at 5% of the critical damping, considering a return period of 475 years, furthermore as reference spectra, the spectra proposed by the New Italian Code for the Buildings have been considered, characterized by different return periods (72, 475, 975 years). The accelerograms, compatible with the spectra, have been performed using the procedure of Sabetta and Pugliese /20/. The recorded accelerograms have been selected by the project of the Reluis /11/ where, for each seismic zone and for each type of soil, a series of 7 recorded accelerograms are proposed, the average of their response spectra is compatible with the spectrum proposed by Ordinanza del Presidente del Consiglio dei Ministri (OPCM n. 3431/05) /17/. Two sets of accelerograms useful for the seismic zone 2 and for the soil type A, considering a return period of 475 years, have been extracted. The results, in term of expected displacements, are similar, confirming the procedure and their importance for urban planning both to perform planning choices and to perform project useful to the security of the landslide.