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

    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

    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.